I. BACKSTORY
A. HISTORY
The history of the Japanese Imperial Navy, 1868–1945, is the story of the navy’s transformation from an odd collection of sailing vessels in the early 1880s into the world’s third most powerful fleet by the end of World War I. The navy’s progress is emblematic of Japan’s meteoric rise from feudal isolation in the mid-nineteenth century to one of the world’s great powers by 1918.1
In the decade 1868 to 1878, the Japanese sailing navy, inadequate even for coastal defense, lacked not only modern warships but also any professional understanding of tactical deployment, any strategic awareness, and any technological and industrial base. Yet a handful of modernizing officials, recognizing the priority of Japanese self-defense, including the establishment of a modern navy, acutely identified the first steps to developing such a force. Although they could not call upon a consistent Japanese maritime tradition, or upon a store of technological expertise, Japan’s military and naval circumstances at the time bore several advantages. First, because Japan had no real fighting navy, it was not burdened by a dominant naval establishment resistant to change, nor by a large fleet that rapid shifts in technology could make obsolescent or expensive to replace. On the contrary, confronted with kaleidoscopic changes in world naval affairs, the handful of forward-looking and decisive leaders who came to the forefront of Japanese political and military development in these years was influenced by the Japanese propensity to adopt the latest and most useful practices, even if they came from abroad. These men were surprisingly able to make wise choices and take fresh initiatives in an era of worldwide strategic, tactical, and technological uncertainty.
In the 1880s, when Japan had limited economic resources and Western power was encroaching on East Asia, it was clear to the Japanese leadership that the strategic priority must be the defense of the home islands. For the time being, Japan’s navy, such as it was, would depend on foreign technology for its modern warships and on foreign instruction for its tactical and technological training until it could build its own industrial base for naval construction and its own autonomous professionalism.
At this embryonic stage of naval development, Japan was particularly fortunate to have a mentor in Britain, although it kept its options open for any and all foreign assistance and counsel. In 1878 one modern steam frigate and two corvettes were built in British yards and delivered by British crews to Japanese ports. Complementing these new fleet units, a series of British naval advisers and instructors introduced Japan’s fledgling officer corps to the latest Western tactical advances and strategic thought.
By the 1880s the navy had taken the first steps in the development of a naval arms industry, including the construction of shipyards at Nagasaki and Yokosuka and the establishment naval arsenals at Tsukiji in Tokyo Bay and Yokosuka south of it. The arsenals, using machinery from Britain, soon began to turn out a few steam vessels of modest size. But for the most part, the navy was still dependent on foreign industry to design and construct its modern fleet. Casting about for the latest advances in naval thinking, the navy came under the influence of the French Jeune Ecole and its emphasis on coast defense, a raiding strategy, and small fast naval units.
Taken together, Japan’s material limitations and this latest trend in Japanese naval thinking confirmed the navy’s defensive posture in the 1880s. But by the end of that decade, the nation’s changed geopolitical concerns sharply altered that outlook. The eastward advance of Russian power across Asia provoked Japanese interests on the continent, particularly on the Korean peninsula where Japanese ambitions confronted Chinese hegemony. This emerging confrontation fueled the support of the government and the public for a force capable of projecting Japanese power into East Asian waters. With the purchase of its three French steel steam-driven cruisers, the navy acquired its first modern warships designed to battle a specific opponent, the Chinese Beiyang Fleet, which included several large warships purchased from Germany.
Simultaneous with the acquisition of its first modern fleet units, the Japanese navy, struggling with its sister service for strategic status, organized itself for combat, constituted itself as an emperor-centered service, established its standing fleets and major base commands, reformed its personnel system, and formulated its first tactical doctrine. These initiatives were in large part due to the vision and ferocious energy of one of the early navy’s greatest figures, Admiral Yamamoto Gombei (1852–1933).
On the eve of the nation’s 1894–1895 conflict with China, the navy had made great advances in the requirements for modern naval combat. Its largest force, the Combined Fleet, centered on ten first-line warships, all foreign-built. Although it was hastily brought together, its unified command, superior speed, offensive doctrine, and superior armament proved triumphant in the war’s several naval engagements, most dramatically in the Battle off the Yalu River, 17 September 1894. Those victories confirmed the lessons the navy had been taught by its British advisers: the tactical superiority of the column over the line abreast, the importance of strict station keeping and the consequent concentration of gunfire, the effectiveness of the torpedo and the quick-firing gun, and the necessity for a homogeneous fleet able to maneuver together. For the navy, its victory over the Beiyang Fleet provided a dazzling argument for its primacy of place in the Japanese armed services.
But victory over imperial China did not bring Japan all the rewards it had hoped for at the beginning of the war. True, it had wrenched from China a large monetary indemnity, the island of Taiwan as Japan’s first overseas colonial territory, and the Kwantung Peninsula with its valuable naval base at Port Arthur. But the “Triple Intervention” (by Russia, Germany, and France) forced the retrocession of Kwantung to China, a national mortification that made clear Japan’s maritime weakness relative to the West. To deal with this humiliation and to plan for an eventual showdown with Russia, Japan undertook two initiatives. It linked itself by treaty with Britain, the world’s greatest naval power, and it set about acquiring sufficient naval strength to confront Russia over the mastery of northeast Asia.
In the process, Japan acquired a battle force of state-of-the-art capital ships, a difficult and risky decision because all navies, trying to find the dominant weapon, the most effective fleet organization, and the most successful tactical system, still labored in a fog of conflicting technological and doctrinal choices. Fortunately for Japan, the nation retained the services of Yamamoto Gombei, whose influence and acumen were greater than his position as chief of the Navy Ministry’s Naval Affairs Department. Thanks to his efforts, in 1896, the navy pushed through the Diet an expansion plan that committed the government to a theoretical standard of naval power not unlike Britain’s “Two-power Standard.” It also represented a conscious effort to match the navy’s qualitative strength against all other naval powers because it called for four new British-built battleships, more powerful than anything yet afloat. This emphasis on quality over quantity was to be a fundamental principle in the navy’s force structure for the next half century.
The decade 1895–1904 saw Japanese advances across a range of naval technologies, including new explosives, ammunition, and fire control. By its alliance with Britain, Japan not only gained access to stocks of superior Cardiff coal but also neutralized the threat of a potential coalition of hostile powers, such as the one presented in the Triple Intervention. During these years, the Japanese Naval Staff College began to shape a modern yet indigenous tactical doctrine that combined Japanese classical military concepts, the navy’s experience in the war with China, and the latest Western innovations. From these different conceptual strands the navy wove together certain lasting principles, including the tactical effectiveness of superior speed, the importance of close-in torpedo attacks pressed home relentlessly, and the necessity of a battle line homogenous in speed and firepower.
Exploiting all these measures on the eve of its war with Russia, Japan had raised itself to fourth among the world’s maritime powers. It was, to be sure, still a navy of regional not global reach. Yet in preparing for a conflict with Russia, whose navy was divided into two fleets separated by the world’s largest continent, this regional focus was a definite advantage. Furthermore, the missions of the Japanese Combined Fleet under the command of the redoubtable Admiral Tōgō Heihachirō were perfectly clear: the defense of Japan’s home waters; the blockade of Russian naval forces in East Asian ports; the escort of a Japanese expeditionary force to the northeast Asian coast; the protection of its maritime communications; and the destruction of any Russian naval force sent from European waters to intervene. In the war that followed, Tōgō’s Combined Fleet carried out all these tasks with superb efficiency. They were crowned by Tōgō’s annihilating victory over the Russian Baltic Fleet in the Tsushima Straits on 27–28 May 1905.
Yet the impact of the war on world naval thinking is less important for this chapter than the legacies it provided to the evolution of Japanese naval doctrine. Of these, the first was the concept of the decisive fleet engagement fought with big guns, a concept that led to the navy’s mantra of “big ships, big guns.” The second legacy of the Battle of Tsushima was the conclusion that a strategy of attrition was the best means of overcoming enemy numerical superiority prior to the decisive battle. Third, the Japanese navy believed that priority must be given to superior quality over quantity in warship design and construction. Last, there was a resurgent emphasis in Japanese tactical thinking on torpedo warfare, less because of any startling results achieved by torpedoes during the war than for the fact that torpedoes seemed to recall the tactics of ancient Japanese land warfare—the thrust of small groups of warriors against the heart of the enemy. But for the navy leadership, the chief legacy of the war was the primacy of the capital ship in destroying the enemy fleet. While this was a concept shared by other navies, for the Japanese it had a special and, it turned out, fatal import. This was because the eventual appearance of submarines and aircraft fundamentally crippled the dominance of the capital ship and the big gun. But beyond even this, the most harmful legacy of the Russo-Japanese War for the Japanese navy was the conviction by Japan’s naval leadership that battle at sea was not only the essence of naval war but that it was the determinant of the whole outcome of a war.
In the decade and a half that followed Japan’s complete victory at Tsushima, several unexpected challenges confronted the nation and the navy. The first of these was that the spreading naval arms race among the Western maritime powers led to a decline in Japan’s relative naval strength from third to fifth among the maritime nations. More immediate was the emerging profile of the U.S. Navy as Japan’s most likely future enemy, a situation caused less by any conflict of interest between the two nations than by the fact that they were now the Pacific’s foremost naval powers. This fact became the strategic focus for Admiral Satō Tetsutarō, Japan’s leading naval thinker, who formulated the concept of the “hypothetical enemy,” which was based on a nation’s ability to threaten the national security of another rather than on its intentions to do so. But the problem in Satō’s identification of the U.S. Navy as Japan’s top enemy was that it ran counter to the strategic priority of the Japanese army, which identified Russia as Japan’s chief hypothetical enemy.
Japan’s 1907 Imperial Defense Policy tried to eliminate this dichotomy and to coordinate the strategy of the two armed services. Ultimately, the 1907 policy only highlighted these fundamentally opposed approaches to grand strategy and designated two hypothetical enemies: Russia for the army, the United States for the navy.
Admiral Satō, having shaped the navy’s strategy toward a naval conflict with the United States, next attempted to provide the navy with a formula by which Japan, as the lesser economic and industrial power, could deal with the quantitative superiority of its projected foe. His “solution” was to call for Japanese maintenance of a set ratio of naval strength vis-à-vis the U.S. Navy. Using historical precedent and mathematical calculation, Satō held that Japan’s maintenance of naval power of 70 percent of American naval strength would be sufficient to defend Japan against the advance of a hostile American fleet. Although its assumptions were flawed, the 70 percent ratio became a bedrock policy of Japanese naval force structure for the next thirty years.
These twin policies—the U.S. Navy as the hypothetical enemy and the insistence on a 70 percent ratio vis-à-vis American naval strength—were paralleled by the navy’s strategic and tactical preparations for the eventual naval conflict with the United States. The acquisition of newer capital ships was of prime importance, of course. Its manifestation was Yamamoto Gombei’s “Six-Six Fleet”—six battleships and six battle cruisers to be built every six years, which was replaced in 1907 with the “Eight-Eight Fleet” concept that became the heart of Japanese naval planning from 1907 to 1922, in large part because Satō Tetsutarō was able to persuade his colleagues on the General Staff that a 70 percent ratio would be impossible without it. Yet clearly the Eight-Eight Fleet idea was ill conceived. In 1907 it was beyond the country’s economic and material resources. Moreover, it undercut established Japanese foreign policy in that it provided no detailed explanation of the supposed American naval threat it was designed to counter. Indeed, the General Staff had almost arbitrarily selected the U.S. Navy as a likely opponent to justify the scale of naval strength the Japanese navy brass desired.
Meanwhile, the progress of Japanese industry and technology was providing the nation with the potential to build a fleet capable of challenging the United States for mastery of the Pacific. In 1910, with the design and construction of four major battle cruisers of the Kongō class, the Japanese shipbuilding industry took a quantum leap forward. The namesake of the class had been built in Britain to specifications that, in certain respects, were more demanding than those capital ships being built for the Royal Navy.
Kongō was the last Japanese warship built abroad. Her sisters were constructed in Japanese yards, and with their completion, Japanese naval construction came of age. Still the goal of an Eight-Eight Fleet lay just beyond the navy’s reach in large part because of the resistance of an economy-minded Diet. Then, in 1916, with the sudden challenge of a new and massive American naval construction program, the Diet authorized an interim naval expansion plan that would have given the navy an Eight-Six Fleet and in 1918, the announcement of still another huge American building program shocked the Diet into actually approving funds (1920) for the Eight-Eight Fleet idea.
The navy’s long-held ambition was not to be realized because, in 1921, the navy reluctantly joined the Washington naval conference, which was called to halt the emerging naval arms race between Britain, the United States, and Japan. The result of the conference, the Washington Naval Treaty, called for a moratorium on further construction of capital ships and, much worse for the Japanese navy, acceptance of a capital ship ratio of less than 70 percent of the Anglo-American navies. Although the navy’s “antitreaty” faction seethed with rage, the naval high command accepted this major limitation in return for unfettered construction of cruisers, destroyers, and submarines, as well as certain restrictions on Anglo-American bases in the west Pacific which appeared to lessen the Western threat to Japanese national security.
Thus began the interwar “treaty era” (1922–1936) in international naval affairs. For the Japanese navy, its force structure and naval construction during this period were shaped by two determinants: the doctrinal concepts in place since the Russo-Japanese War and the navy’s perceptions of the evolving strategy of the U.S. Navy, more than ever seen by the Japanese as their most likely future opponent. In turn, these determinants rested on six basic Japanese assumptions about the nature of a conflict with the United States: first, that a Japan-U.S. naval war would be determined by a single great battle-fleet encounter in the mid-Pacific; second, that victory in that encounter would be determined by superiority in big guns; third, that it was imperative that the war be short, since Japan, with its smaller industrial base, would eventually be overwhelmed in a protracted war under an avalanche of American ships and weapons; fourth, that to have any hope of defeating the United States in a naval war, it was imperative that Japan enter the conflict with at least 70 percent of the strength of the U.S. Navy; fifth, that as Japan would undoubtedly open the war by seizing the Philippines and the United States would undoubtedly react by sending a battle fleet and expeditionary force across the Pacific to reoccupy the islands, the site of the great big-gun duel would probably be somewhere in the western Pacific; and sixth, that because the American battle fleet would be numerically superior at the outset of the war, it would be vital for the Japanese navy to develop weapons and tactics that would reduce the American battle line to at least parity before the decisive encounter.
With more than seventy years’ hindsight, we can see how badly the Japanese misunderstood the lessons of World War I. Although Japanese navy men (along with their opposite numbers in various Western navies) were transfixed by the big gun duel at Jutland in 1916, that battle was in fact a strategic and tactical dead end. The real import of the war at sea was the German U-boat campaign against Britain that nearly brought that nation to its knees. Of this campaign, the Japanese navy, even though it had had observers at the British Admiralty who sent back data on the German submarine peril, took little cognizance, obsessed as its leadership continued to be with big ships and big guns.
At the end of the war, the navy made a reassessment of the international situation and subsequently undertook the first revision of the Imperial Defense Policy of 1907, a revision that took note of the changes in the international balance in naval power: German naval power temporarily obliterated, Russian naval power dramatically shrunken, Anglo-French naval power in Asia and the Pacific sharply reduced, and American naval power massively increased. This last change reinforced the view of the U.S. Navy as Japan’s prime hypothetical enemy and in this regard simply rekindled old disagreements with the army.
A matter of far greater import was the strategic recasting of the navy’s force projection compelled by the Washington Naval Treaty of 1922. Obliged to abandon further capital ship construction, the Japanese navy turned to the next best substitute: the heavy cruiser. Devoting intensive research to the design and construction of these ships, the navy came to possess the most powerful warships of this type afloat.
But the navy did not stop at the cruiser. As torpedo units, destroyers and submarines were seen as potentially contributing to a powerfully enhanced capability to whittle away American numerical superiority in capital ships. This was a conviction stemming from Japanese operations in the Sino- and Russo-Japanese wars that relentless night torpedo attacks were the best way to reduce enemy heavy units. In the 1920s, this conviction was buttressed by the design of large, heavily armed destroyers and the most powerful torpedoes (24-inch) of any navy. By the 1930s, the Japanese destroyer, with its nine to twelve torpedo tubes, was a specialized all-out attack vessel, unlike its jack-of-all-trades counterparts in Western navies, and was seen as the most effective weapon to break through the enemy screen and throw the enemy’s capital ships into disorder before the onset of the big gun duel. Throughout the 1920s and 1930s, in order to achieve this objective, the navy refined its torpedo techniques through relentless and often hazardous night exercises.
Submarines were expected to perform a roughly similar function, launching attacks on American fleet units from Japanese bases in Micronesia. During the interwar period, the Japanese navy built some of the world’s largest submarines to extend Japanese reach to U.S. warships off the American West Coast. As a strategy, it might have worked for a while, but it was a high-priced gamble because the submarine as a devastating antifleet weapon had not been consistently tested in World War I. What had been tested and proven was the effectiveness of submersibles as raiders against merchant shipping. But despite the clear evidence of this fact, the Japanese navy saw commerce warfare as irrelevant to the Japanese warrior tradition. By setting aside what Japanese submarines could do to American shipping, the navy compounded its error by thus failing to understand what American submarines could do to Japanese merchant shipping, a failure that was one of the major reasons for Japanese defeat in the Pacific War.
But the Japanese drive to construct the world’s most powerful cruisers sparked a new and heated building race between Japan and the United States, whose interests and positions in this category were deadlocked. Whereas the United States opposed any reduction in the tonnage of individual cruisers, destroyers, and submarines but supported reductions in the aggregate tonnage of these lesser ship types, the Japanese navy was adamantly opposed to reductions in aggregate tonnage, particularly in heavy cruisers, and was determined that it not be compelled to accept the sort of lesser ratio that had been forced on it at Washington for capital ships. In 1930 the British and American navies had called for a conference in London to do just that, in order to complete the system of naval limitations begun at Washington. The London conference did indeed result in a treaty that obliged Japan to accept a reduction in naval strength not only across the board but also an actual reduction in strength relative to the Anglo-Americans in cruisers, a category in which the Japanese navy had labored, with effort and skill, to obtain a lead. By 1934 the white-hot anger of Japan’s “antitreaty” faction made clear its determination to take Japan out of the entire naval limitations system when it expired in 1936 and, in the meantime, to prepare for the furious new naval race that would erupt in a treatyless world. Until then, the navy had to deal with the realities created by the London Treaty. Its response, undertaken with skill and ingenuity, was to build to its allotted tonnage in each of the restricted warship categories and to strengthen those weapons and systems not covered by the treaty.
The first material results of this effort were a series of construction programs that came to be known unofficially as the “Circle Plans.” There were four of them drawn up between 1931 and the outbreak of war in Europe in 1939. The first Circle Plan, in 1931, realized the ambition of the General Staff to give Japan a qualitative lead in cruisers by placing within a cruiser hull the maximum firepower allowed under the London Treaty. The result was the B-class cruiser of 8,000–10,000 tons. More heavily armed and armored than any Japanese “light” cruiser heretofore, these ships possessed greater firepower than any British or American cruiser of similar tonnage. Similar changes in design were undertaken across a range of lesser warship categories.
The addition of heavier batteries and deck armor resulted in excessive top weight and thus dangerous instability. The consequences of these defects were not long in coming. In March 1934 the torpedo boat Tomozuru capsized in a gale, and in September 1935 units of the Fourth Fleet, on maneuvers in the North Pacific, were caught in a huge typhoon and a considerable number sustained heavy damage or capsized in the mountainous seas. The Tomozuru and Fourth Fleet “incidents” sent shock waves through the navy, which redesigned ships under construction and retrofitted units already in service to give them greater stability. In this, however, these mishaps may have worked to the navy’s advantage, since the modifications in design and construction were undertaken when the navy had the time and resources to make them.
But accidents at sea in the 1930s were not the only stimulus to retrofitting and reconstruction in the navy. Continuing modernization projects had been going on since World War I not just in the Japanese navy but also in all navies. During the 1922–1936 treaty era, all major units of the Japanese navy were rebuilt as part of a considered program of modernization. Beginning in the late 1920s through the end of the next decade, all Japanese capital ships went into the yard for improvements in main batteries, bridge structures, fire-control systems, deck armor, and antitorpedo protection. During these years, advances in steam engineering and fire control marked important technological improvements that contributed to the Japanese navy’s tactical flexibility and strategic reach.
But similar advances in the British and American navies more than matched these improvements. Beginning in the early 1930s, the U.S. Navy in particular embarked on a major naval construction program. The United States’ naval expansion programs shocked Japan. Its naval leadership, dominated by the vehement “antitreaty faction,” had worked tirelessly to have their nation abrogate the naval arms limitations agreements and free itself from the Anglo-American imposition of a 60 percent ratio in major warship tonnage. A maritime world without agreed-upon naval arms limits, however, proved more threatening to Japan than its naval leadership had foreseen. The United States, also freed from treaty limits, could now put its industrial might into naval rearmament that surged far beyond those limits. The successive American expansion plans eventually extinguished Japanese hopes of attaining a 70 percent ratio (let alone parity) with the U.S. Navy.
Given this ominous reality, the Japanese navy’s only recourse, as its leaders saw it, was acquiring exceptional weapons, further improving tactical skills, and making up for a deficit in quantity by means of quality. In the navy’s posttreaty era, this conviction led to critical decisions, of which its “superbattleship strategy” is only the most famous.
That strategy emerged during consultations between the Navy General Staff and Navy Ministry in 1934 concerning the third “circle” plan by which the navy, freed of the former treaty restrictions, could build a fleet capable of overpowering the larger American maritime enemy. It comprised several elements: the continued modernization of existing fleet units, the construction of sixty-four new warships of various types, and the achievement and maintenance of parity in naval air power. But its chief component was the construction of two superbattleships—the Yamato and Musashi—designed to be superior in armament, armor, and speed over all other capital ships for years to come and thus capable of crushing any American capital ships in the long-projected great gun duel at sea.
It has become popular to view these two naval monsters as technological dinosaurs at the time of their design, doomed by air power, the weapons system that caused their destruction in the Pacific War. It cannot be denied that, as a type, the battleship had outlived its dominance and had been overtaken by air power by the opening of the Pacific War. But in the early years of the 1930s, when the two monsters were conceived and when aircraft were still relatively frail machines incapable of carrying ordnance of significant explosive power, the concept behind their design made a good deal of sense. The failure of the navy’s superbattleship strategy lay rather in certain inherent defects in the design of these ships, in the rapid and inevitable advances in other technologies after they were conceived, particularly in the destructive power of aerial torpedoes, and most of all because the superbattleship strategy diverted the navy’s attention and resources away from the most critical strategic problem confronting the navy and the nation: Japan’s dependence on its overseas supply and communications routes and the vulnerability of shipping on those routes to submarine and aerial attacks.
B. MISSION
In 1936, when Japan abrogated the Washington treaty and set a course for renewed naval expansion, the navy’s mission was now to contest the U.S. Navy for control of the entire Pacific. But even then this mission was reactive and regionally focused: a response against an American fleet moving westward to relieve or retake Guam and the Philippines threatened or seized by Japan at the outset of hostilities.
A real change in the navy’s mission did not occur until Admiral Yamamoto Isoroku assumed command of the Combined Fleet in 1940. Soon after taking command, Yamamoto began his initial planning for a preemptive attack on the American Pacific Fleet in Hawaii, which would inevitably stretch the projection of Japanese naval power across the vast distances of the Pacific.
A. COMMAND STRUCTURE
1. Administration
High Command. Any explanation of the organization and administration of the Imperial Japanese Navy has to begin with the Japanese sovereign. Theoretically, the emperor—whose person and authority, according to the Japanese constitution, was “sacred and inviolable”—reigned supreme over all government agencies and institutions, including both armed services, but in fact, his practical involvement and responsibility in the operation of government were limited by tradition and law.
Functioning beneath the emperor were the armed services, the civilian government headed by the prime minister, and certain prestigious but generally passive advisory bodies. The prime minister’s cabinet included the ministers of the two armed services who were selected by and nominally responsible to the prime minister. In reality, the army and navy ministers looked to the chiefs of staff of their respective services for direction because they were usually officers on active service. They could, and sometimes did, bring down a civilian cabinet by refusing to serve in it. In any event, real power in both armed services resided not in the ministers, who were generally responsible for administration, but in their general staffs.
The Navy General Staff was composed of three divisions—operations, intelligence, and readiness—and was charged with the preparation of war plans, collection of intelligence, setting the requirements for the navy’s force structure, drafting warship designs, and direction of operations at sea. The chief of the Navy General Staff, acting in the name of the emperor, held “the right of supreme command,” which meant that he was responsible only to the emperor and not to the civilian government. In theory, all plans devised by the navy general staff required imperial sanction; in practice, the emperor approved them automatically. This meant that, with the exception of the submission of the navy’s annual budget to the Diet, the navy was accountable to no one else.
This system had several baleful consequences. The first was the fact that, because the will of the emperor was “sacred and inviolable,” all who acted in his name could not be obstructed in the conduct of their duties by anyone outside the navy—a recipe for chaos in the conduct of Japan’s foreign policy. The second consequence was equally pernicious. Because of the untrammeled authority of the armed services, there was no effective civilian voice to raise an objection or to point out the folly or danger of a particular military initiative. This proved to be a crippling defect in the conduct of Japanese military operations in the Pacific War, beginning with the decision to go to war.
The Navy Ministry was the largest organization in the Japanese naval high command and was largely concerned with the administration of the navy, its finances, appropriations, personnel, training, and logistics. Within the ministry were a number of powerful and independent bureaus and departments, of which the Naval Affairs Bureau was the most important. The navy’s appropriations process began with the Navy General Staff, which sent to the ministry its force requirements and its warship designs and specifications. The ministry, in consultation with both the staff and the Finance Ministry, translated these into monetary figures that were formed into an appropriations request that was submitted to the Diet. Although the Diet could theoretically reject the request or any part of it, by the 1930s it seldom did so because of the dominating position of the armed services and their strong public support. But in a period of increasing naval expenditures, such as World War II, the General Staff’s relentless demands for expansion drove the civilian government to near bankruptcy. These arrangements help to explain how, over time, the Japanese navy, like its sister service, came to develop two insidious tendencies: first, its extreme reluctance to accept any compromise that appeared to infringe on its authority; and second, the evolution of its various divisions and departments into a web of bureaucratic satrapies, each jealous of its prerogatives and each less than devoted to the principle of interservice harmony and coordination. In the last two years before the Pacific War, the emergence of powerful ad hoc intraservice committees standing outside the navy’s formal bureaucratic structure proved insidious creating additional fissures within the navy. Added to these internal tensions was the far more serious enmity between the two armed services that, like scorpions in a bottle, sought to inflict painful bureaucratic injuries on each other. It is because of this bureaucratic enmity that Japan never developed an effective coordinating body such as the Joint Chiefs of Staff in the United States. It was tried, of course, in the form of an Imperial General Headquarters (IGHQ), reestablished in 1937.2 But the IGHQ never really functioned as an effective coordinating body. Its structure was too weak, it had no overall executive, and its two parts came together as bureaucratic rivals only to negotiate matters of strategy, as between independent states. This situation was symptomatic of one of the basic reasons for the Japanese defeat in the Pacific War: the inability of the army and navy to work out an effectively integrated strategy.
Fleet Commands. The Combined Fleet was in effect the overall command of Japan’s oceangoing navy. In terms of fighting, it was the Japanese navy, comprising all combat elements except the China Area Fleet, the special naval landing forces, the land-based air groups, and the base units.
The Combined Fleet had been formed at the outset of the first Sino-Japanese War and disbanded at its conclusion. It was periodically reconstituted on a temporary basis for a specific purpose until 1924 when it was made a permanent command composed of the 1st and 2nd Fleets but without a headquarters staff of its own because the commander of the 1st Fleet served concurrently as commander of the Combined Fleet. In 1933, with tensions rising with China, a permanent headquarters staff was established and the Combined Fleet commander was made at least theoretically responsible to the Navy General Staff.
Subordinate to the Combined Fleet were the area fleets responsible for specific geographic areas. Area fleets usually comprised one or more fleets and air fleets. While area fleets possessed major warship types, most capital ships and carriers served with mobile fleets, and the 6th Fleet was composed entirely of submarines.
In addition to these semipermanent combat fleets, during the Pacific War the Japanese navy also formed temporary “mobile fleets” for specific operations. Operating under the overall command of a mobile fleet were one or more “strike forces,” in concept not unlike the “task forces” of the U.S. Navy during those same years but with far less logistical “tail” and thus far less staying power at sea.
Japanese naval aircraft were formed into air groups (kōkūtai), either land-based or carrier-based. Carrier air groups were composed of three squadrons each of fighters, dive-bombers, and torpedo-bombers; several carrier air groups made up a carrier division (kōkūsentai) usually composed of two or more carriers. The land-base equivalent of a carrier division was an air flotilla (also kōkū sentai). Several air flotillas made up an air fleet (kōkū kantai) composed of either land-based aircraft, or, oddly, sometimes both land and carrier-based air groups.
2. Personnel
Both in peace and war, the navy met its manpower needs by relying on a small cadre of career officers and men who were highly qualified and rigorously trained rather than creating a professional core backed by a much larger reserve of men with some training who could be mobilized to swell the ranks in wartime. Over the decades, pursuing this personnel policy of quality over quantity, the Japanese navy built a small, elite force of some of the world’s best trained, best disciplined, best motivated, and most experienced naval professionals. With such a cadre of officers and men, the navy had won two major naval wars in the first thirty years of its history.
Because of the rigors of the Japanese navy’s training and because of its technical proficiency, during the treaty era, the Japanese navy’s personnel were probably equal to and, in some cases, superior to those of the Anglo-American navies. The difficulties began in the mid-1930s, when the navy launched its posttreaty expansion plans and found itself short of personnel to man a rapidly growing surface fleet, an expanding air service, sizeable naval landing forces, and all the elements of its shore establishment. As the navy began to pile one expansion program on top of another, the situation worsened. Between 1936 and 1941 the navy estimated it was roughly eight hundred to a thousand officers short. The real trouble came during the Pacific War, of course, when difficulty in manning new naval construction was compounded by mounting combat injuries and fatalities. By the middle of the war, when many of the midlevel officers had been killed, the problem reached crisis proportions. The creation of a strong, reasonably trained reserve in the prewar decades, such as the U.S. Navy had developed, would have considerably lessened this critical situation.
While the average Japanese naval officer was highly intelligent, heroically brave, and loyal unto death, Western naval historians have cataloged serious weaknesses in the navy’s officer corps: the absence of independent and rational judgment in the average naval officer, his lack of assertiveness, the narrow tactical concerns that monopolized his higher naval education at the Naval Staff College, and the overweening pride of service that perpetuated the navy’s continuing and destructive rivalry with the army.3
Training was rigorous for all sea service and combat personnel but particularly for air crews. Between the world wars, surface units trained ferociously under conditions that the navy attempted to make even more difficult, stressful, and dangerous than the combat conditions it anticipated. The consequent casualties caused by this extreme training deterred the navy high command not at all. In the naval air service, the demanding selection process weeded out all but the most perfect physical specimens; of those who washed out, many were in the horrendously demanding training with the Kasumigaura Air Group (basic flight training) or the Yokosuka Air Group (advanced and combat air training). Two parallel air training programs were the Pilot Trainee System, which recruited and trained noncommissioned officers, and the Flight Reserve Enlisted Trainee System, which drew its candidates directly from civilian life. In either case, such flight training involved relentless and rigorous drill through which only a small, elite group of pilots were able to pass.
By the eve of the Pacific War, therefore, the Japanese navy possessed some of the best fighter pilots in the world—many of them gained combat experience in the skies over China—but their numbers were shockingly small, and there was no large reserve of good but less brilliantly skilled pilots behind them. It was a personnel policy that was to work to the navy’s great disadvantage in the latter half of the Pacific War.
The essential cause of the navy’s crippling personnel policies was simply a lack of foresight. A policy that relied on entering combat with a small elite of highly trained professionals would have undoubtedly suited the kind of short conflict centered on the single battle that the navy planned to fight. It was a fatal defect in waging the extended war of attrition that the navy was actually obliged to fight.4
3. Intelligence
The navy’s intelligence capabilities were central to Japanese victories in the spring of 1942, and its limitations were critical in the navy’s greatest defeats thereafter. Both were the result of certain anomalies in the structure and status of the navy’s intelligence organization. The first of these was the bifurcation of function at the highest level, the Navy General Staff, whose intelligence responsibilities were divided between its intelligence division, which performed most of the standard intelligence functions, and the communications division, charged with cryptanalysis and communications security. More important was the limited role and influence of the intelligence division in the formation of Japanese naval policy and strategy. The principal function of the division was to provide relevant and timely information to the operations division. Combining such information with communications intelligence and with tactical intelligence from various fleet units, the operations division could then prepare estimates of enemy capabilities and intentions. But, surprisingly, the intelligence division did not evaluate the information it collected and passed on. Moreover, within the operations division, information supplied by the intelligence division was often ignored as suspect or irrelevant. Worse, operations, fixated on its own agenda, sometimes initiated plans without even consulting intelligence. Because of this stunted development, intelligence, particularly after 1937, became an understaffed adjunct to operations and never developed into a coordinated body capable of collecting, possessing, and disseminating useful intelligence throughout all levels of the navy.
The limited influence of intelligence in the Japanese navy was a crippling drag on its specialized personnel and training. There were too few capable intelligence officers and little effort was made to improve their skills. Most naval officers regarded an intelligence billet as a career dead end and the navy made little effort to make intelligence work professionally rewarding. This situation affected all aspects of intelligence, including communications intelligence and photoreconnaissance, and was a failure for which the General Staff and Combined Fleet were both responsible. It was a defect that originated in the navy’s fixation on combat to the neglect of critical but less heroic aspects of naval warfare.
Like most intelligence organizations, the intelligence division gathered its information from a variety of sources: translation of foreign books and journals, reports of naval attachés and clandestine operatives abroad, navy-run espionage centers in foreign countries, and reports from Japanese consulates concerning foreign ship movements. But the greatest source was interception of foreign radio traffic, the responsibility of the “special division” after 1940. Within that organization was a code-breaking research branch and a communications unit located southwest of Tokyo, which became the navy’s chief radio intercept center—able, in the 1930s, to track the maneuvers of American fleet units in the Pacific. From the 1920s, the navy also began to experiment with fleet tankers as clandestine floating intercept stations, particularly off Hawaii. Still, with the exception of one or two mode breakthroughs, the Japanese navy was unable to make significant headway in reading American radio traffic before and during the Pacific War. Even the mid-level American code systems proved beyond the skills of Japanese cryptographers.
Unfortunately for Japan, the United States was superlatively successful in breaking certain Japanese systems before the war, particularly the Japanese diplomatic codes. The most important Japanese naval codes—the “Ko” and “Ro” systems—were more resistant to solution. The “Ko” or “flag officers code,” used for its highest level communications, was never completely solved by the U.S. Navy before the war and was abandoned by the Japanese navy in favor of the “Ro” code (called JN-25 by the U.S. Navy), which became the Japanese navy’s most widely used cryptographic system.5
One last comment may serve as a summary judgment on Japanese naval intelligence. It is undeniably true that, as of December 1941, the navy’s tactical intelligence on the Allied military situation throughout the west Pacific and Southeast Asia was precise and comprehensive. What was critical and absent was any information or analysis of the broadest issues: the recuperative powers of the United States once it had absorbed the first Japanese blows, and the vast American industrial and military capacities that in the months to come would enable the United States to launch counterblows with a speed and force which the Japanese did not anticipate. For the Japanese navy and nation, this was the most critical intelligence failure of all.
B. DOCTRINE
1. Surface Warfare
There were, of course, certain tactical principles in the Japanese navy that predated the concept of “big ships, big guns” (taikan kyohōshugi). One dogma can be traced all the way back to Japan’s traditional warrior culture—the concept of fearless, close-in attacks against the enemy—that can be summed up in one of the navy’s tactical mantras: “press closely, strike home” (nikuhaku hitchû), a concept that first inspired the torpedo boats and destroyers of the modern navy in the Sino-Japanese war. This remained a cardinal tactical principle in the years before the Pacific War when the navy considered that the role of cruisers and even battleships was to blast a breach in the enemy heavy formations for the destroyers to exploit, rather than viewing the lighter craft as opening the way for capital ships, as in American tactical doctrine.
Nevertheless, the most influential voice in navy doctrine and force structure was that of the so-called gun club (teppō-ya), which insisted that the “big ships, big guns” policy was the quickest and surest means to win the great encounter at sea. The importance of the biggest guns was predicated on two assumptions: first, that such guns could fire the heaviest shells and fire them over the greatest distances, far outranging the enemy’s ability to retaliate; and second, that improvements in technology would make it possible to concentrate that shellfire. By 1917 the concept had hardened into dogma, and over the next two decades, through simultaneous improvements in gunnery, “outranging” in the form of long-range concentrated shellfire became a basic doctrine of the Japanese navy.
The reader must not assume, however, that in the minds of Japanese tacticians the concept of outranging was limited to the heaviest ships. In the 1930s, to give medium and light surface units greater reach, the Japanese navy searched for means to give torpedoes greater range. After some years of intensive research, Japanese technicians devised a formidable new weapon: the famous Type 93 oxygen torpedo, which was wakeless and of greater size, speed, and payload than any available in any Western navies. Exploiting the potential of the new weapon, Japanese naval tacticians worked out a new torpedo tactic—long-distance concealed firing—and developed a new class of light cruiser to carry it out.
2. Aviation
Although the culture of the Japanese navy shaped its offensive mindset, until the mid-1930s the limited performance of aircraft around the globe—in speed, range, ceiling, and payload—meant that aviation was not seen as an offensive asset. In the early 1930s, Japanese naval orthodoxy held that “command of the air” was meaningful only in relation to support for the surface fleet as it prepared for the great gun duel at sea, in other words, for reconnaissance and spotting for naval gunnery.
Not surprisingly, during these years, Japanese naval aviation was subject to some of the same tensions and controversies that troubled naval air services in the West. Chief among these was the difference of opinion about the relative performances of fighters and bombers. Fighter aircraft had dominated the skies over western Europe in World War I, but by the early 1930s bombers were seen as superior in performance for offensive operations, and fighter aircraft were relegated to fleet air defense.
Out of numerous practices and exercises in the 1930s, the navy reached four conclusions about carrier warfare: first, that the winning side would be the one that got in the initial blow; second, that such a blow must “outrange” the enemy; third, that such a blow must be delivered by carrier attack aircraft—dive and torpedo-bombers; and fourth, that it was less important to try to sink an enemy carrier than it was to destroy its flight deck because a carrier without aircraft was as harmless as a tennis court.
By the end of the decade, given the navy’s traditional preference for offensive operations, some observers foresaw the eventual extinction of the fighter from the navy’s inventory. But this situation was reversed in 1940 with the appearance of the Mitsubishi Type 0 A6M (Zero) carrier fighter. In the wild combat in the skies over China, the navy’s pilots brilliantly displayed the amazing capabilities of this aircraft as well as their own superlative flying skills and exquisitely honed teamwork. Yet, if the Zero was emblematic of the cutting edge of Japanese naval aviation on the eve of the Pacific War, it was also symptomatic of the weaknesses of that service. An inadequate power plant and lack of protection for pilot and fuel tanks were ultimately to prove fatal in combat with American fighter aircraft, and these defects made no sense in relation to the precious handful of pilots the navy possessed.
3. Antisubmarine
Protection of merchant shipping and overseas trade routes should have been a natural and logical priority for Japan. Despite building a significant number of oceangoing submarines that could blockade ports on the American West Coast, Japanese naval strategists never seem to have considered the possibility that Western navies could do the same to Japan. Little thought was given to constructing quantities of cheap antisubmarine warfare (ASW) vessels or to upgrading existing ASW tactics, techniques, or weapons.
4. Submarine
The story of the Japanese submarine force is the story of missed opportunities. Although Japan acquired a formidable collection of submarines whose numbers included some of the largest of their type as well as midget submarines that could be carried aboard surface ships or larger submarines, Japanese submersibles did little to affect the course of World War II.
The problem began with the fact that the navy gave its submarine force a flawed mission: the long-distance interception of American fleet movements in the Pacific. Although Japanese submarines did score some dramatic sinking of American warships (the carrier Yorktown at Midway and the heavy cruiser Indianapolis at the end of the war, for example), too often American surface warships were too fast and too evasive for the Japanese navy’s standard pursuit, contact-keeping, and attack formulas.
These difficulties related to an essential problem in submarine tactics for all navies prior to and during the war: the opposing requirements of stealth and surprise through subsurface concealment on the one hand and, on the other, aggressive action that obliged a submarine to come at least to periscope depth where its periscope and torpedo wakes might give away its position. Forced to choose between these two, Japanese submarine commanders often chose stealth over boldness, which meant that they usually failed in their missions as enemy fleet units raced by unscathed.
The most glittering opportunity presented to the submarine force came early in the Pacific War: the chance for a major blow to the American conduct of the war by attacks on shipping to and from the American West Coast. Had the Japanese navy concentrated its submarines in such operations in the spring of 1942 at the same time that the German navy was massacring shipping along the East Coast, such a coordinated assault might have set back American strategy in both the Pacific and Atlantic by many months. But, caught up in its early victories in Southeast Asia and in its fixation with the great surface battle in the mid-Pacific, the navy let that opportunity slip by.
5. Amphibious Operations
Whereas aviation, submarine, and antisubmarine warfare all had significant successes in World War I, the Allied landings at Gallipoli, the war’s most ambitious amphibious operation, had been a disastrous failure. After the war, most military and naval establishments—the U.S. Marine Corps excepted—viewed Gallipoli as a confirmation of the extreme difficulty, if not impossibility, of conducting a landing from the sea in the face of an armed, entrenched, and determined enemy.
Yet early in the interwar period, the Washington Treaty had given both the United States and Japan an incentive to maintain an amphibious capability in the Pacific. As the treaty prohibited both the construction of new bases in the western Pacific and the strengthening of existing bases there, any conflict between the two powers would require the occupation of enemy bases or the recapture of bases lost to the enemy. It was not that the Japanese knew nothing about amphibious operations. Nearly all of Japan’s modern wars had involved army landings on an enemy coast and had required navy transport and fire support. Indeed, Japan was one of the first nations to understand the importance of modern amphibious capabilities without which it could not have established a military presence on the Asian continent. But the army’s mission in these conflicts was principally devoted to the great land battles inland. The navy maintained a modest ability to project power ashore. Beginning in China, the navy assigned landing operations to ad hoc landing parties (rikusentai). These units were usually composed of personnel from Japanese gunboats plying Chinese rivers. The sailors selected were given a modicum of infantry and small arms training and were put ashore when the need arose. Later, in the 1930s, standing landing parties were stationed permanently ashore in barracks and armed with heavy weapons, including 3-inch howitzers.
The army gave hardly any thought to amphibious doctrine until after World War I. In the late 1920s, it collaborated with the navy in a series of joint exercises in the western Pacific where some of the problems of combined amphibious operations were worked out. By 1932 the two services had developed a series of guidelines for such operations, and that same year the navy created a permanent, specialized naval landing force for small-scale amphibious operations. By the outbreak of the Pacific War, the two services had developed a set of three simple doctrinal principles for their amphibious operations: land on essentially undefended shores; land at night, or at the latest, at dawn; and land at several places simultaneously. These were the tactics used by the Japanese in their flood tide of advance through Southeast Asia in early 1942. Their landings, often at night, were carried out with speed, surprise, and economy of force by units that landed separately but concentrated at the point of attack. Their effectiveness was clearly measured by the consequent confusion and demoralization sown among the Dutch, British, and American defenders of those tropical shores.
But as effective as such operations were, it is clear that they were essentially unopposed landings, not amphibious assaults—heavily armed frontal attacks out of the sea in daylight in the teeth of determined resistance by an alerted, entrenched, and well-fortified enemy. The Japanese never mastered that mission before the war because it must have seemed to them that it would not be necessary. Yet, in the long run, they paid dearly for their ignorance of this more violent face of amphibious warfare. Certainly, that ignorance is one of the principal reasons why, during the entire war, the Japanese were never able to retake an island base once lost to the American enemy.
6. Trade Protection
Given the vulnerability of the Japanese home islands to naval blockade and the potential danger to its overseas commerce from naval attack, the Japanese navy’s indifference to these perils is incredible. On a theoretical level, of course, the navy acknowledged the problem of protecting the nation’s maritime trade, but it undertook few concrete measures that would make such protection effective. There were multiple reasons for this: restricted budgets, the priority given to major surface combat, and preparations for the anticipated great gun duel at sea.
The navy entered the Pacific War with a feeble understanding of the basics of trade protection. Essentially, the navy had regarded it as an extension of the problems of coastal defense, a view that might have had some marginal relevance when the nation’s interests were confined to the shorelines of the home islands but that made absolutely no sense when those interests had thrust onto the Asian mainland or, later, into Southeast Asia. Thus, on the eve of Japan’s conflict with the United States, the Navy General Staff, in its Olympian complacency concerning the safety of Japanese shipping in the event of war, had given little thought to the general problem of trade protection, or to its subsidiary elements—the requirements of ASW, the tasks of convoy and convoy escort, and the need for relevant and accurate intelligence concerning American submarine doctrine and capabilities. It had little in the way of organization, weapons, tactics, training, personnel, or doctrine that could effectively defend the nation’s maritime transport. In consequence, disaster awaited.
7. Communications
The advent of ship-borne radio or, more exactly, radio telegraph provided Japanese commanders at sea a rapid and effective means of communicating with their forces, thus exercising more effective tactical control over them. Radio was a great asset to Admiral Tōgō in his victory over the Russian Baltic Fleet in 1905.
The great weakness of radio, of course, was the vulnerability of communications to interception. The attempt to protect radio communications through encoding and encryption inevitably provoked counterefforts by other naval establishments for the decoding and decryption of such messages. In this context, the Japanese navy, lacking the appreciation of the importance of this “intelligence revolution” wrought by radio communications and failing to mobilize knowledgeable civilian talent for such encryption and decryption, increasingly fell behind the western maritime powers.
In the late 1920s, the navy began the first serious attempts to develop radio communications for its aircraft. In 1929 the first Japanese-designed radio equipment was produced and a communications unit was added to each air group. But the navy’s airborne communications were spotty, as they were for the air services of all nations between the world wars. Crystal-controlled equipment maintained selected frequencies accurately but operated on only a few such frequencies. Analog equipment covered relatively broad frequencies but drifted frequently because of vibration and the idiosyncrasies of electronics.
III. MATERIEL
A. SHIPS
At the opening of the Pacific War the Japanese navy possessed warships that were among the world’s best in nearly every category. Of course, to assess what is the “best” warship is a problematical task given that ship design, like aircraft design, requires a series of trade-offs among performance capabilities. Any particular design will perform better in certain combat tasks and environments than in others. That said, it is clear that Japan’s monster battleships Yamato and Musashi were the most heavily armored and the most powerful gun platforms ever launched. While they had serious defects, the ultimate futility of their creation lay not in their design but in the foolish uses for which they were employed in their relatively short lifetimes. Both succumbed to aerial assault and were never employed in a Japanese battle line confronting American capital ships—the scenario for which they were originally conceived.
Whereas these two superbattleships represented the apogee of capital ship construction, the navy’s other battleships and battle cruisers contributed substantially to the Japanese navy’s awesome reputation as a fighting force. Its four Kongō-class battleships were among the world’s most formidable (eight 14-inch guns and twenty-seven- to thirty-knot speed) when they were launched just before and during World War I, and all underwent extensive modernization over the next several decades (increased armor, greater elevation for their main batteries, and added fire control platforms).
The two Nagato-class ships, which had been laid down during World War I, were also modernized in the 1930s. The two Ise-class and the two Fusō-class battleships (twelve 14-inch guns) were famed for their towering superstructures. The Fusōs slugged it out with American forces in the battles in Leyte Gulf in October 1944, with the loss of Fusō and Yamashiro.
PHOTO 5.3. The light cruiser Tenryu dressed for a prewar occasion. (The Boris Lemachko Collection)
Given the moratorium on new capital ship construction dictated by the Washington Treaty, the Japanese can be credited with maintaining a capable capital ship fleet during the interwar period. That these ships were eventually overwhelmed by their American enemy had less to do with their design and construction than with the overpowering quantitative superiority of American industry and the fact that they lacked certain technological advantages, such as the latest and most effective surface radar of the kind installed on their American counterparts.
Japan’s participation in the Washington Treaty obliged the navy to consider what other warship types might be designed as substitutes for the battleship and battle cruiser. The navy’s solution was the development of the “A” class, or heavy cruiser, which was permitted under the terms of the treaty to be of up to 10,000 tons displacement and armed with main batteries of not more than eight inches.
Immediately following World War I, the Japanese navy had already experimented with the light cruiser, a warship type capable of acting either as a fleet scout or as a destroyer flotilla leader. Some seventeen ships of this type, designed for this dual purpose, were constructed in the Tatsuta, Kuma, Nagara, Sendai, and Yubari classes in the 1920s. But the navy’s search for an all-purpose substitute for the capital ship continued and eventually led to a series of heavy cruiser classes constructed during the interwar “treaty era.” The Japanese successes in designing a cruiser that would combine high speed and heavy armament within a hull of modest proportions was due to the imagination and exacting calculations of the navy’s technical department, specifically to the chief of its basic design section, Hiraga Yuzuru. Hiraga’s original design, if unexceptional in its armament, was ingenious in its hull structure and armor arrangements. These incorporated the armored elements (composed of high tensile and hardened chromium steel) in the hull’s internal structure rather than bolting them onto existing plates and beams. This not only reduced the weight of the hull but also added to its strength.
The first “A”-class cruisers were Furutaka and Kako, whose greatest offensive punch was provided by their twelve 24-inch torpedo tubes. Improved Class “A” cruiser classes were added one after the other. The two 7,000-ton cruisers of the Aoba class were given six 8-inch guns in three turrets. But even before the Aoba and her sister Kinugasa were laid down, the navy set out to design a cruiser that would not only reach treaty specification limits but would also be superior to every other cruiser afloat. The result was the Myōkō class of four heavy cruisers, ships of great speed (thirty-five knots), heavy armor, ten 8-inch guns, and twelve fixed 24-inch torpedo tubes. In the design of the Myōkō class, however, the General Staff’s insistence on heavy armor and on mounting the torpedo tubes within the hull not only made the ships heavier than treaty limits allowed but also made them so dangerously top-heavy and unseaworthy that these defects had to be corrected by substantial reconstruction in the 1930s.
By the end of the 1920s, heavy cruisers had come to occupy a central place in the navy’s operational planning. A first division of heavy cruisers—the four ships of the Myōkō class—was formed early in the 1930s. Then, in 1935, the General Staff established a second and even more powerful cruiser division, one composed of the four ships of the Takao class. These were 10,000-ton vessels, armed with main batteries of ten 8-inch guns, capable of more than thirty-three knots, and a range of eight thousand miles at fourteen knots.
The ships of this class were to serve as an advance guard for the fleet, as an attack force to break into the elements supporting the enemy’s battle line, or individually, in a reconnaissance role. Most importantly, they were expected to function as flagships for the fleet during both day and night combat involving torpedoes and long-range gunnery. The increasingly complex installations required to direct these various operations were grouped together in an enormous bridge complex, a centralization of command applications achieved at the cost of great topside weight and a higher profile for enemy gunnery.
Aviation was one of the few components of sea power in which the Japanese navy did not have to scramble to catch up with the Anglo-American maritime powers because Japan’s first efforts in this element were roughly contemporaneous with Western initiatives in the decade after World War I. To be sure, it posed a set of difficult tasks and uncertain assumptions for both naval architects and tacticians in all the major navies. In addition to the usual problems of propulsion, hull structure, seakeeping, and crew accommodations, aircraft carrier designers in both the U.S. and Japanese navies had to deal with a host of difficulties posed by flight operations. As aircraft developed greater engine power and speed, they needed increasing flight deck length for takeoff. Moreover, the still uncertain function of carriers and their place relative to the battle line left open the question as to whether they needed deck guns for self-defense.
These problems were manifest in the construction of the Hōshō, Japan’s first and essentially experimental aircraft carrier. From the perspective of later years, the Hōshō, at less than 8,000 tons and with a flight deck of only 552 feet, was a very small carrier. The configuration of her hanger deck was such that it permitted the embarkation of only twenty or so aircraft. As larger and faster attack aircraft were developed, her modest size meant that she could embark only fighters and that her function had to be limited to training or, at best, to contribute to the fleet’s air cover. But as the navy’s laboratory for carrier design, construction, and flight operations, she justified the cost of her construction.
With the acquisition of the carriers Kaga and Akagi, originally laid down as capital ships and then converted to aircraft carriers, Japan acquired its first fleet carriers. Still experimenting with carrier design, the navy added certain features, such as deck guns and triple flight decks, that eventually proved impractical and were eliminated or altered in subsequent reconstruction of both ships in the 1930s. During their lifetimes, however, the Kaga and Akagi demonstrated the great potential of carrier aviation in the war with China, in the Hawaii operation, and in the grand sweep in the northern Indian Ocean in the spring of 1942.
Because construction of these ships had already accounted for 54,000 tons of the 81,000 aggregate tonnage allowed Japan for carrier construction under the terms of the Washington Treaty, the navy decided to use the remaining permitted tonnage in the building of a carrier of under 10,000 tons displacement. The result was Ryūjō, Japan’s smallest carrier since Hōshō, a vessel with almost no armor protection and only one hanger. Later improvements, including the addition of a second hanger, made the ship less stable. That in turn put her twice into dry dock in the mid-1930s to improve her stability, but given her small air group, she was never an efficient fleet unit.
The lessons learned in the construction and reconstruction of the Ryūjō were applied to the two carriers of the 16,000-ton Sōryū class. They were designed with cruiser hull configurations and thus were fast ships, capable of thirty-five knots. Sōryū was built with a small island on her starboard side; her sister, Hiryū had it located on the port side. Sōryū could embark sixty-eight aircraft of various types, and Hiryū, seventy-three.
With the expiration the Washington Treaty in December 1936, Japan was now free to build as many ships of all classes as it could afford, including carriers of unprecedented size and performance. During the five years before the Pacific War, the navy added Shōkaku and Zuikaku, the finest carriers that Japan ever built. They were conceived as forming a carrier group able to operate with Yamato and Musashi, a mission that called for large, fast carriers capable of mounting a powerful aerial strike force and able to defend themselves with their own air cover. Their specifications called for the same aircraft complement (ninety-six) as the remodeled Kaga and Akagi, a top speed of thirty-five knots, and a range of ten thousand miles at eighteen knots. Because of their main deck armor, they were ten thousand tons heavier than the Sōryū class but still had excellent stability. Their engines delivered ten thousand more horsepower than even the superbattleships. Until the wartime entry of the American Essex-class carriers, Shōkaku and her sister outclassed every other carrier. Indeed, so valuable did the Japanese consider them that the decision to mount the attack on Pearl Harbor was based in part on their availability for that operation.
Ships that entered service after the war started include Taiho and Shinano. The 29,300-ton Taiho, designed as the Japanese answer to the British Illustrious and American Essex classes, was Japan’s first carrier with an armored flight deck. With a thirty-three-knot speed and a capacity for sixty aircraft, she could have been an effective asset but was torpedoed by an American submarine in June 1944, only three months after she was commissioned. Shinano, the largest carrier Japan ever built, was designed and laid down as the third of the Yamato class of superbattleships but was converted during the war to a carrier. At 62,000 tons, she was a potentially awesome platform for air operations, but with her great fuel and ordnance stowage capacity, she was to have been fitted out as a replenishment and support ship for carrier task forces. But she did not live long enough to fulfill this function; an American submarine torpedoed her in November 1944, ten days after completing trials.
There were also a number of lesser carriers drawn from the navy’s “shadow fleet” of auxiliary and merchant vessels designed to be quickly converted into aircraft carriers as needed. As a group, these conversions were not a success because their minimum protection, modest aircraft capacity, slow speed, and inadequate power from their diesel engines made them ineffective as fleet carriers.
By a number of standards, the Japanese had been innovators in carrier design; in 1941 the two Shōkaku-class ships—the culmination of prewar Japanese carrier design—were superior to any carrier in the world then in commission. They had certain defects, certainly, some of which they shared with American counterparts, some of which were unique to their own service. Like American carriers, they sacrificed armored decks in order to embark more aircraft and thus more offensive power. Their flight decks consisted merely of wooden planking lengthwise over thin steel decks. Again like American carriers, their flight decks were for the most part simply superimposed upon the hull rather than being constructed as strength decks supporting the hull as in contemporary carriers in the Royal Navy.
But there were differences, too, between Japanese and American carrier design and construction. The first had to do with maximum aircraft capacity. As in the Royal Navy, Japanese carrier aircraft capacity was determined by the size of the hangar rather than the flight deck because Japanese carriers stored their aircraft in hangars rather than on the flight deck, as did the Americans. Second, the hangars in Japanese carriers were enclosed by storerooms so that aircraft and ready crews were shielded from wind and weather, but when enemy bombs penetrated the hangars, the resultant blast pressures could be disastrous to the integrity of the ships’ structures. Moreover, the enclosed spaces prevented the disposition of fuel and ordnance over the side in case of fire and complicated the easy insertion of fire hoses from screening ships in order to fight fires. The final difference lay in flight operations. American carriers used crash barriers to separate parked and landing aircraft whereas the Japanese needed to clear flight decks during flight operations. Thus, during continuous flight operations, elevator cycles governed launch and recovery speeds.
In the long run, however, it was not carrier design that determined the outcome of the naval air war in the Pacific but simply the overwhelming quantitative superiority of the United States to turn out carriers, aircraft, and air crews. Comparative data demonstrate this awesome disparity. From 1942 to the end of the war in the summer of 1945, the Japanese navy constructed and acquired by conversion 15 aircraft carriers. During that same period, the U.S. Navy added 141 carriers.
As earlier noted, the Japanese navy placed a greater premium on night combat, particularly night torpedo operations, than any other navy in the interwar period. By World War I, the principal warship for such operations was the destroyer, a type on which the navy relied for the delivery of relentless torpedo attacks even at the cost of heavy losses.
Despite having several destroyer classes of excellent design, the onset of World War I found the navy with too few of these ships for patrol and escort duty. Beginning in 1914, therefore, the navy undertook an emergency program of destroyer construction, the best of which was the fifteen-ship Minekaze class, a new type of destroyer constructed between 1917 and 1922. They were fast vessels (thirty-nine knots) capable of weathering the frequent heavy seas of the north Pacific because of their long hulls and the retention of the turtle deck construction of Japan’s older destroyers, carrying their torpedo tubes directly behind the forecastle and having their unshielded guns as high as possible to maximize their use in heavy weather. The Minekaze class and the twenty-one units of the Kamikaze and Mutsuki classes formed the backbone of Japanese destroyer flotillas during the 1920s until replaced by the famous Fubuki class at mid-decade.
The Fubuki class owed its creation to the Japanese search for a radically enhanced surface capability—largely that of torpedo units—to spearhead the navy’s strategy for the distant attrition of any westward-moving American fleet at the outset of the war. The twenty-four ships of this class built between 1922 and 1931 with their 1,600-ton displacement and their nearly 400-foot length were the most advanced and powerful destroyers of their day and the archetype of most Japanese destroyers that saw action during the Pacific War. Because of their enclosed bridge, fire-control spaces, and gun mounts, their fighting qualities were outstanding even in heavy seas and bad weather. Their six 5-inch guns, mounted in pairs in three turrets, were not only weatherproof but also splinterproof. Ammunition for this ordnance was brought up on hoists directly from the magazine under each turret, thus providing a high rate of fire. Indeed, these arrangements for their main batteries (years before such arrangements were adopted for destroyers in other navies) gave the Fubuki class fire power equal to that of many light cruisers.
But it was the greatly increased torpedo armament that made the Fubuki class the most powerful destroyers afloat. Each ship carried eighteen 24-inch torpedoes, two each for the nine torpedo tubes housed in three triple mountings, an arrangement that provided a larger torpedo salvo than available on destroyers of any other navy.
By the 1930s, therefore, the Japanese destroyer, with its nine to twelve torpedo tubes, was an all-out attack vessel. Its dominant role was its original torpedo boat function, a purpose considerably more specialized than the typical destroyer in the U.S. and British navies, which had become a jack-of-all-trades warship. Throughout the interwar period, the Japanese navy took advantage of its outstanding destroyer classes and refined its night torpedo tactics through continued, relentless, and often hazardous exercises and, by the outbreak of the Pacific War, had forged a formidable offensive asset. But the navy would come to regret that, in burnishing so bright a specialized weapon, it had neglected the less glamorous duties of a destroyer: scouting, convoy escort, patrol duty, and antisubmarine warfare.
B. AVIATION
Immediately after World War I, such was the promise of aircraft to project naval power beyond the range of ship-borne weapons that the world’s three major navies, which now included Japan, felt impelled to create a naval air arm in one form or another. By the 1920s each had constructed at least one prototype aircraft carrier as well as designed carrier-based, water-based, and land-based aircraft.
Initially the modest abilities of these first naval aircraft hardly seemed a serious threat to naval surface units. Until the 1930s, they were so limited in their capabilities in terms of speed, range, ceiling, and payload that, in the Japanese and Anglo-American navies, “command of the air” was viewed by the battleship-oriented brass only in relation to the decisive surface engagement.
While none of the trials of naval aviation in World War I had proved decisive and much of aviation’s potential remained speculation, the Japanese navy was not slow to grasp the significance of new aviation technology and, even before the end of the war, had begun to develop some of its own aircraft. Yet the gap in aviation technology between the West and Japan had widened considerably since Western belligerents had gained practical understanding of the design requirements for combat and valuable experience in the mass production of aircraft. The postwar decade in Japanese aviation technology was therefore marked by two intensive and interrelated initiatives: the infusion of Western technological assistance and vigorous domestic efforts to establish a Japanese aircraft industry. The first was realized by the invitation to Japan of a British civil aviation delegation—the Sempill Mission—that provided the navy with the latest Western aviation technology as well as the latest air combat tactics and techniques. Japanese efforts to establish its own fledgling air industry were facilitated by a number of institutional innovations: the granting to the Navy Technical Department, in 1921, the authority to issue competitions for the design of aircraft according to specifications laid down by the Navy General Staff; in 1927 the creation of the Naval Aviation Department made responsible for the development (but not the production) of air frames, engines, ordnance, and equipment; in 1932 the establishment of the Naval Air Arsenal to coordinate aircraft design and flight testing; and the institution of the navy’s “Prototypes System,” a managed competition in the design and development of naval aircraft by the Japanese aircraft industry.6 These organizational details are important because they are basic to an understanding of the navy’s ability to develop some of the finest combat aircraft in the world in the 1930s, which moved aviation from the margins to the center of naval power by the opening of the Pacific War.
1. Ship-based
Carrier Aircraft. In 1934 the navy began a search for a new single-seat carrier aircraft to replace its current biplane fighter. Because of the stringent requirements imposed by carrier flight operations, a successful design demanded a careful selection of performance priorities within the specifications set forth by the Navy General Staff. The Mitsubishi A5M Type 96 carrier fighter brilliantly satisfied the greater number of these priorities. It was an all-metal, open-cockpit, low-wing monoplane powered by a 500-hp radial engine and armed with two machine guns mounted in the engine cowling. Its aluminum construction, flush rivets, and smooth contouring sufficiently reduced air drag so the designers were able to retain its fixed landing gear. The A5M’s superb maneuverability underscored the navy’s emphasis on dogfighting although its speed (280 mph) and rate of climb (16,000 feet in six and a half minutes) were also unprecedented in Japanese aviation. The appearance of the A5M, along with the G3M medium bomber (see below) marked the emergence of an ambitious program of aircraft reequipment for the navy and signaled the entry of Japanese aviation into an era of self-sufficiency.
Even as the A5M was scoring triumphs in the skies over China in the summer and fall of 1937, the navy was moving ahead with the design of an aircraft that would surpass it in performance. In the opinion of the front-line pilots in the China War, the need was for a fighter with the speed and firepower to destroy enemy bombers, the range and endurance to escort the navy’s own medium bombers, and the maneuverability to deal with any enemy fighters along the way. They also wanted a fighter that would meet the challenging demands of carrier flight operations. To satisfy these requirements, the Naval Aviation Department proposed a carrier fighter whose design specifications were of unprecedented difficulty because they were so contradictory. The Mitsubishi team that had created the A5M won the design contract and now created the A6M, eventually known throughout the world as the “Zero” fighter, solving most of the competing staff specifications through a series of ingenious adjustments in structural components, revolutionary advances in construction methods, and the use of innovations such as retractable landing gear and fuselage streamlining. In 1940 the Zero was one of the most ingeniously designed aircraft in the world. In speed, radius, firepower, rate of climb, and turning radius, it was one of the premier combat aircraft in the world. Initially thrust into the fighting in the skies over China during 1940–1941, it decimated Chinese air units, successes that were to be repeated in the Japanese sweep through Southeast Asia in early 1942. Its dangerous weaknesses—structural fragility, the vulnerability of it fuel tanks to enemy fire, and the modest output of its engine—were not revealed until it met the more rugged and more powerfully engined American aircraft during the latter half of the Pacific War.
During the late 1930s, the navy developed two categories of attack aircraft to arm the flight decks of its carriers: torpedo- and dive-bombers. By 1937, in the Nakajima B5N Type 97 torpedo-bomber, it had an aircraft that could undertake multiple roles: torpedo attacks, reconnaissance, and high-level bombing. After its adoption by the navy, the B5N almost immediately went into carrier service; as a participant in the assault on Pearl Harbor, a B5N is credited with dropping the killer bomb that sank the battleship Arizona. The plane also saw service in China where it performed well in supporting Japanese ground operations.
The Aichi D3A Type 99 carrier dive-bomber was remarkably rugged for a Japanese combat aircraft. In range and structural integrity, it compared favorably with the American Douglas Dauntless (although it was slower) and with the German Stuka. In the first year of the Pacific War, it sank more Allied warships than any other Axis aircraft.
Long-range Flying Boats. During the interwar years, the Japanese navy recognized the need for long-range over-water reconnaissance. For this purpose, it developed the large flying boat. The experience of the Kawanishi Aircraft Company in developing this type of airplane led to the creation of the H6K Type 97 flying boat, which the navy adopted in 1938. A parasol-winged aircraft powered by four radial engines, its range of 2,200 miles gave it a dramatic reach over vast oceanic distances early in the Pacific War. But its vulnerability to enemy fighter attack eventually led to its replacement by its hardier successor, the Kawanishi H8K Type 2 flying boat, a high-winged aircraft also powered by four radial engines but with a range of almost 4,000 miles. It was for a time the world’s best flying boat.
In 1930, when Yamamoto Isoroku assumed direction of the technical bureau of the Naval Aviation Department, one of his first priorities was the development of an effective land-based long-range bomber. After a year (1935–1936) of Mitsubishi’s testing an ever-improving series of bomber prototypes, the navy accepted an advance model of the Mitsubishi G3M Type 96 medium bomber in June 1936. A sleek, all-metal, twin-engined monoplane bomber with a payload of either 800 kilograms of bombs or a single torpedo slung under its fuselage, its range of 2,300 miles and its ceiling of 30,000 feet were unprecedented except for the contemporary American B-17 Flying Fortress. But like other Japanese aircraft, its weaknesses—the absence of protective armor, and inadequate defensive armament—were revealed in its combat operations over China, 1938–1939.
In any event, even as the G3M entered combat, the navy began working on a successor that would have better power plants, greater speed, increased payload, increased range, and better defensive armament. In early 1940 the navy accepted the G4M Type 1 medium bomber. During the first six months of the Pacific War, the G4M spearheaded Japanese offensives in the west Pacific and Southeast Asia. It was, early in the war, a formidable weapon and achieved some remarkable successes: raids deep into central China in 1941, the sinking of the British capital ships Repulse and Prince of Wales at the opening of the war, and the bombing of Port Darwin in Australia in 1942. Nevertheless, the old nemeses of Japanese aircraft design—structural fragility and vulnerability to enemy fire—often proved fatal to the aircraft in combat situations. Indeed, the G4M caught fire so easily that its aircrews gave it an ominous sobriquet, “The Flying Lighter,” and American fighter pilots gave it the dismissive name of “Zippo.”
At the time of their appearance, the small group of Japanese naval aircraft displayed some of the most advanced aviation technology in the world. Flown by highly skilled aircrews, the navy’s planes collectively constituted an immensely dangerous offensive force. Yet they also collectively demonstrated the fatal weaknesses of Japanese naval air technology. Of these, the most serious was the failure of Japanese industry to keep up with the West in the development of powerful, lightweight aircraft engines. This in turn was the consequence of Japan’s inability to have access to strategic alloys essential to the development of such engines. The superior power plants of American aircraft were a major reason for the increasing losses of Japanese aircraft in combat in the latter half of the Pacific War. But there were also serious problems in the design of Japanese aircraft. Considerations of speed, range, and maneuverability so monopolized the concerns of Japanese engineers and aircrews that the Japanese aircraft discussed herein were bereft of all but the most minimal protection and defensive armament. These deficiencies would have been serious even if Japan had had a limitless pool of highly trained aircrews. With the small number of such personnel available, they would prove fatal to Japanese prospects in their combat with their sturdier American opponents in the skies over the Pacific.
C. WEAPON SYSTEMS
1. Gunnery
That the Japanese navy devoted much time and attention to gunnery in its early decades was evident in the effectiveness of its gunfire in the naval battles of the Sino- and Russo-Japanese wars. Of course, in an era when fire control was still in its primitive stages in all navies, in these encounters the Japanese achieved a fraction of hits by their main batteries out of the total number of shots fired. That said, that fire, particularly at the Battle of Tsushima in 1905, was awesomely destructive due to the force and explosive power of Japanese shells. Admiral Tōgō’s annihilating victory at Tsushima proved to be a milestone in naval warfare because it proved the primacy of long-range firing (6,000–10,000 m) and thus heralded the dominance of the biggest guns.
In the near-decade between the Russo-Japanese War and the outbreak of World War I, the problems of surface fire control in naval gunnery were beginning to be understood in the major navies but insufficiently solved to exploit the potential ranges of rifled ordnance. While, by 1905, primitive fire-control systems had advanced partial solutions to the problems of target tracking, predicting range and bearing, and correcting aim based on observation, such systems were slow and imperfectly integrated. For the Japanese navy, the period 1905–1914 was not one of great technological innovation in fire control, and the Japanese relied largely on advances by the British navy in this regard.
During World War I, however, the Japanese did attempt to develop fire-control instruments, and this program laid the foundations of the navy’s fire-control systems between the world wars. In the 1920s, the navy’s increasing obsession with “outranging”—striking the enemy at the outset of a battle from a distance at which he could not retaliate—led to several technological improvements that made it possible to coordinate the long-range fire of main battery ordnance. By mid-decade the navy had sufficient confidence in its guns and gunnery that it believed its main force units could outrange those of the U.S. fleet by four to five thousand meters. However, the course of this technological development in these years was at a slower pace than in the American and British navies. During the first year of the Pacific War, the superior quality of Japanese optics and the training and skill of Japanese gun crews enabled Japanese gunnery to more than match the American enemy, but thereafter, as the U.S. Navy fully exploited its advances in fire-control radar and high-powered servomechanisms, Japanese gunnery could no longer hold its own.
Electronics, particularly radar, was the most vital field of technology in the naval side of the Pacific War. Disastrously for the Japanese navy, the development of electronics was a case of too little, too late. This is ironic because Japanese research in the field had begun in the early 1930s, at almost the same time as in Britain and the United States. Yet official indifference, haphazard mobilization of civilian scientific expertise and talent, and (as always) the absence of interservice cooperation fatally delayed the practical application of Japanese radar research.
With the outbreak of the war in Europe and the recognition by the navy of some of the advances in radar made in the West, the navy’s interest in this new technology accelerated to the point when, in August 1941, the Navy Ministry finally ordered a crash program in radar development. The first meter-length air-search radar set was ready in late November 1941, but it was an electrically and mechanically crude device by Western standards. By the opening of the Pacific War, the navy still had no shipborne surface search or fire-control radar. Confident at the outset of hostilities in its night combat doctrine and equipment (powerful optics and searchlights), the Japanese navy found itself a year into the Pacific War fighting like a man blindfolded.
Despite the urgent demands of the Navy General Staff for accelerated development of radar, the inability of Japanese naval researchers to produce centimeter wavelength magnetrons and the severe staff specifications for radar sets made it impossible for the navy’s research staffs to develop effective radar models in the time they were given. Without doubt, prewar American advances in radar and the Japanese failure to match them were among the reasons for American naval victory and Japanese naval defeat in the Pacific War.
2. Torpedoes
Torpedoes were a favored weapon in the Japanese navy from its early years, and most of its warships were equipped with torpedo tubes by 1893. The torpedoes used by the navy in the Sino-Japanese conflict were of German manufacture based on the original Whitehead design, but in 1897 the navy began producing its own Whitehead-type torpedoes at the Tokyo Naval Arsenal.
The torpedo remained a weapon of choice for the navy well into the twentieth century and was a central element in the navy’s night operations exercises. But these exercises revealed a serious problem: the potentially prohibitive losses among the destroyer units assigned to undertake them.
The solution was for destroyers to fire their torpedoes at long range, for which the navy needed a powerful, wakeless torpedo. The navy undertook intensive research on and testing of such a weapon in the 1920s and early 1930s and by the latter half of the 1930s had developed the formidable Type 93 oxygen torpedo. This appeared to be the navy’s ideal weapon for outranging the enemy and was installed on many Japanese cruisers and destroyers by 1940. In addition to the Type 93 for surface vessels, the navy later developed an aerial version, the Type 94, and a submarine version, the Type 95.
3. Antisubmarine Warfare
Given the prewar Japanese complacency toward trade protection and ASW, it is not surprising that its ships, weapons, and the equipment to deal with these matters were too few in number and poor in quality. The marginal attention given to protection of sea transport was reflected in the paucity of naval construction devoted to it. Just before the London Naval Treaty, the navy briefly considered building a sizeable force of specialized vessels for trade protection, but budgetary limitations (at a time when the navy was considering its superbattleship strategy) aborted the plan and the navy built only four small multipurpose coast defense vessels whose size (860 tons), speed, and armament were inadequate for an ASW mission. Fourteen vessels of an improved type were planned, but none had been completed when the Pacific War began.
Not only was the number of vessels assigned ASW duties inadequate for their mission, their weapons and equipment were largely ineffective for any such task. They had no forward-thrown ASW weapons, and their main armament was inferior to the larger deck guns of American submarines. Their underwater detection gear was obsolete, their sonar was rudimentary, and the settings for their depth charges were faulty (too shallow because Japanese intelligence had underestimated the maximum diving depth of most American submarines).
4. Mines
Mines had been in the navy’s arsenal from its early days but were used with modest success only in the Russo-Japanese War when they sank a Russian battleship. By the 1930s, due to the navy’s increasing emphasis on aircraft and to its protective improvements for surface warships, mines had become obsolete weapons.
D. INFRASTRUCTURE
1. Logistics
Until it initiated the Pacific War, the Japanese navy had been only marginally concerned with logistics.7 In its first two combat tests—the Sino- and Russo-Japanese wars—the navy’s logistical requirements were simple and adequately met. But these were conflicts of short duration against close-at-hand enemies. A naval war with the United States fought over vast oceanic distances against an enemy formidably supplied by an enormous industrial base confronted the Japanese navy with huge logistical problems. Beyond the critical question of oil stocks, there was a serious shortage of ammunition, particularly in aviation ordnance. Although the navy maintained the flow of ordnance at the start of the war, it was haunted by ammunition shortages throughout the remainder of the conflict.
Turning to logistical procedures, the navy high command had clearly not anticipated the need for materiel and expertise required for the construction of forward bases in the Pacific. Specifically, the navy lacked the specialized organization, training, and equipment to make such construction possible. In particular, it lacked the requisite equipment—bulldozers, earthmovers, and steam shovels—of modern civil engineering; therefore, nearly all of its construction was by hand. As the tide of the Japanese advance swept through the southwest and central Pacific, the navy came to recognize the need for specialized units to build airfields and other advance base facilities. The first such construction units (setsueitai) were organized in November 1941, but they were only semimilitary in character and had scant combat value with little of the expertise, training, equipment, or weapons possessed by the U.S. Navy’s Seabees. As the tide of the Japanese offense slowed and then stopped, the mission of the setsueitai was redirected to the construction of defensive works on the islands they had captured. But overwhelmed in a series of futile defenses as the American counteroffensive began to roll westward through the central Pacific, they were immolated in the bunkers they had helped to construct.
The fundamental cause of the Japanese navy’s prewar failure to recognize in advance the logistical problems in a war with the United States was again the navy’s fixation on the long anticipated great gun duel at sea. Only less capable or more physically limited officers were assigned to grapple with the difficulties of transport, supply, and construction, and their views were rarely sought by those officers planning and directing combat operations. Hence, the latter tended to frame their plans without relation to logistical resources and their plans often failed disastrously.
2. Bases
From its earliest years, the Japanese navy maintained several types of base commands, each headed by an officer formally subordinate to the direct authority of the emperor. By the 1890s, the coastal defense of the islands was entrusted to three separate naval districts, each centered on a naval base that served as both a “primary port” and the naval headquarters of the district. The port included building yards, fuel and supply depots, naval barracks, and the anchorage for guard and coast defense vessels. In peacetime each district was under the authority of the Navy Ministry; in wartime it came under the direct command of the area fleet attached to the district. Within each district were also “naval ports,” a secondary type of base that included repair shops, naval hospitals, and an anchorage for more coast defense vessels.
As Japan acquired overseas possessions, it also established “strategic ports,” which were the overseas equivalent of a domestic naval base. After the League of Nations awarded Japan a mandate in Micronesia following World War I, the navy began eyeing the possibility of establishing bases in the Mariana and Caroline islands as well. With its entry into the air age, the navy also began establishing air bases that would provide not only airfields but also headquarters for its various land-based air groups. There were twelve of these in the home islands and one in Korea by 1937. These air bases were established at the moderate pace compelled by the traditional pick-and-shovel construction that the navy practiced.
After the outbreak of the Pacific War and Japan’s sweep through Southeast Asia, the navy took over existing air and naval bases established by Western colonial powers. The real difficulties for the navy began when the course of the war entered the central and southwestern Pacific and the navy was confronted with the need to construct bases on undeveloped coral atolls and in remote tropical bays. To level the ground, build docks, lay down airstrips, and erect buildings and revetments the navy had little earth-moving machinery and slight expertise of the sort enjoyed by the American Seabee construction battalions. This deficiency was not a critical problem initially as the navy swept eastward in the Pacific, but it became so after the tide of war turned and the first American amphibious counteroffensives surged westward. Without avail, the Japanese navy attempted to throw up effective land defenses in the Pacific, but these were overwhelmed by storms of American naval gunfire, air bombardment, and waves of landing infantry.
3. Industry
Japan’s defeat in World War II is often explained entirely by the avalanche of American resources, materiel, and weapons that simply buried Japanese forces. Certainly, the enormous output of American industry after 1942 makes this a plausible explanation. But the serious incapacities of Japanese industry during the period 1942–1945 are just as important in assessing the awesome material disparity between the two combatants.
The workings of Japan’s war industry are too complex to be analyzed comprehensively here, particularly since we have Jerome Cohen’s Japan’s Economy in War and Reconstruction, which remains the classic English-language study on the subject.8 Much of what is said here is drawn from the most salient points in his chapter on Japanese industry.
Initially, Cohen asserts, the Japanese high command, specifically including the navy, made the decision to go to war with great confidence that Japan had an adequate supply of weapons and equipment of all types that it would need for the conflict. From their Olympian perspective, they noted that munitions output currently exceeded expectations and that naval construction had surged during the previous decade. But this confidence was based on the nation’s experience in its war in China, which had largely involved conventional land weapons and which had been fought against a materially inferior enemy. A conflict with the United States would be principally a maritime conflict, one requiring not only warships of every size and type but also a vast array of aircraft, electronic devices, and antiaircraft weapons; mountains of ammunition of all calibers; hundreds of cargo ships and tankers; and oceans of naval fuel and aviation gasoline. Moreover, the changing tides of war would require unanticipated shifts in the kind of ships, aircraft, weapons, and equipment needed, which would in turn necessitate alternative production plans during the course of the war and would thus slow industrial output across the board.
Japan encountered this last difficulty by the end of 1942, when it appeared that Japan’s greatest need was for cargo vessels to bring to Japan the great treasure house of strategic raw materials that it had captured in Southeast Asia and that were now desperately needed by the industrial machine in the home islands. In this regard, wartime Japan depended on its merchant shipping even more than beleaguered Britain (which, after all, was largely kept in the war by American supply convoys). At the beginning of the China war, Japan had one of the world’s largest merchant fleets and thus turned its shipbuilding industry to strengthening its naval forces through modernization of older vessels and construction of new ones. But because Japan’s available stocks of steel were limited, new or reconstructed warships came at the sacrifice of further merchant ship construction. This would have posed a difficult dilemma for the navy in any event, but the mounting losses of both warships and merchant shipping to American submarine and air attacks soon made the situation critical. By 1944 an overriding need was for more tankers to import Southeast Asian petroleum for a thirsty navy. Even before the war, Japan had had too few large tankers, and as American submarines began to sink tankers as a target priority, the need for such vessels rose dramatically. In addition to the problem of limited stocks of steel and other metals used in ship construction, there were insufficient shipbuilding facilities. Good sites for ship construction—expanses of flat land near both rail links and deep water—were rare; where they did exist, they were usually located on city waterfronts where any expansion of dockyards was difficult and expensive. In consequence, expansion of existing facilities usually caused congestion, confusion, and disruption of a smooth and systematic flow of construction output. Newer yards, often specialized in their construction functions, avoided some of these difficulties, but they usually had a smaller and less experienced workforce, a condition that created its own problems.
As the war progressed, the growing number of ship losses in both naval and merchant vessels put a terrific strain on Japanese industry to make up for them. But after the first year of the conflict, there were never enough materials, facilities, or skilled workmen to meet the nation’s needs. Equal to problems of low stocks of material was the question of manpower and its effect on the production of everything from radios to battleship turrets. Here the demands of the military were both dominant and shortsighted. All too often the military drafted skilled workmen and technicians to serve as ordinary seamen or common soldiers, a policy that contributed to the chaotic course of industrial production.
Japan’s aircraft industry was shockingly vulnerable to aerial destruction as well as to disruption from lack of planning. To begin with, the industry’s factories were extremely concentrated. For example, 72 percent of aircraft output was located within a thirty-five-mile radius of three large cities—Tokyo, Nagoya, and Osaka—and only four aircraft companies produced more than two-thirds of all aircraft during the war. Two of the largest aircraft plants located in Osaka produced 92 percent of Japan’s aircraft between 1941 and 1945.
Even more than shipbuilding, the Japanese aircraft industry suffered from interservice friction and duplication as well as an ever-shifting emphasis in combat unit demands. Added to shortages of strategic metals and skilled labor, such chaotic conditions lowered production efficiency, not to mention the failure to keep abreast of Western advances in aircraft design and technology.
Part of the problem, of course, was that the Japanese lacked the vast research capacity available in the United States. While the United States enjoyed the findings of numerous commercial research laboratories such as Bell, RCA, Argonne, and Westinghouse as well as a number of government research institutions, Japan had very few of these. This meant that the number of specialists available to think through problems in technology, communications, logistics, and intelligence was far smaller in Japan than in the United States; thus the nation lagged behind its enemy in these important fields, with adverse consequences both in staff planning and on the fighting fronts.
Such knowledgeable advice might have avoided some of the grave mistakes by the military at the start of the war, particularly the failure to connect plans for airframe and engine production with the realities of materiel requirements. Before 1942, according to Cohen, there was no real effort to determine the exact raw-material requirements for the aircraft industry as a whole. Nor had the navy made any effort to stockpile rare alloys used in the making of high-tensile-strength special alloy steels. Shortages of nickel, copper, chromium, tungsten, cobalt, and other strategic materials eventually led to a decline of alloy steels for aircraft engines, fuel systems, motor mounts, and landing gear. Such material shortages, in combination with the deteriorating quality of workmanship eventually caused a significant drop in the operational availability of Japanese naval aircraft. At the outset of the war, the navy was able to count on the availability of 80 percent of its aircraft. That percentage dropped to 50 percent midway through the war and for some air groups to only 20 percent.
Shortages in fuel stocks also contributed to the decline in the quality as well as quantity of Japanese naval aircraft. Low stocks of aviation gasoline meant that the navy tested engines less frequently. Early in the war, the navy tested its newly built engines for nine hours; by the end of the war that figure was down to two hours, and only one out of ten engines was being tested.
A. WARTIME EVOLUTION
For more than three decades, between the Russo-Japanese War and the Pacific War, the Japanese navy planned, trained, and armed itself for combat with a single opponent, the U.S. Navy. In assessing these preparations, one should survey, if only briefly, the course of the naval war in the Pacific.
For the first two years of the war, the Japanese navy fought, often with great success, using the tactics and technologies it had perfected during the interwar period. From early 1944, however, it suffered calamity in the face of the enormous buildup of American forces and the U.S. Navy’s extraordinary technological advances in naval warfare. From that time forward, the Japanese navy waged a war of desperation, largely abandoning its prewar tactical and strategic thinking.
The outset of hostilities was initiated by the navy’s thunderous attack on the U.S. Fleet at Pearl Harbor, which remains to this day a marker for tactical triumph and strategic error. Had the Japanese concentrated their effort on the conquest of Southeast Asia—which was, after all, their primary strategic objective, not the Pacific Fleet at Hawaii—the American fleet would have come lumbering westward across the Pacific, very likely to have been sunk in deep water by Japanese bombers based in Micronesia.
In the first months of the war, the Japanese navy essentially limited itself to the strategic goals set forth in its immediate prewar planning. In this, the conquest of Southeast Asia was accomplished with a speed that surprised even the Japanese themselves. After its strategic successes in the first half of 1942, the navy turned to the second phase of its plans: the elimination or neutralization of those strategic points from which the Allies could launch counteroffensives against the periphery of Japanese conquests. There the Japanese met for the first time with serious strategic reverses, first at the Coral Sea, when they were forced to abandon their effort to isolate Australia; then at Midway, when their attempt to establish a steppingstone for an assault on Hawaii resulted in the loss of four carriers; and finally, in the seven-month-long fight to control the Solomon Islands, in which the navy ultimately lost a campaign of attrition. In each of these campaigns, Japanese naval operations followed a pattern that significantly undercut the prospects for success: a failure to concentrate its forces at a time when it still held superiority in the Pacific. This was particularly critical in the Japanese defeat at Midway.
After Midway, the navy once more turned its attention to the southwest Pacific. There, in a campaign centered on the struggle for Guadalcanal, both Japanese armed services lost ground, ships, aircraft, men, and materiel through piecemeal commitment of their forces. The consequent loss of strategic initiative made the Solomons campaign the decisive period of the war. But more serious to Japanese prospects than the destruction of the navy’s men, ships, and aircraft in that campaign was the gift of time and space it gave to the United States. During 1943, with the battle lines in the Pacific at a standstill, America was able to gather and reorganize its forces. Most critically, thereafter, the United States’ vast industrial plant and array of scientific skills began to affect the outcome of combat.
Once halted in their drive to expand Japan’s strategic periphery beyond the limits of prewar planning, in 1943 Japan’s armed services turned their energies to the defense of the perimeter of their earlier conquests. But Japanese preparations to rush to completion a barrier against the American amphibious counteroffensive were puny compared to the enormous scale of the force gathering against them. The United States launched against the overextended Japanese a type of sea power so revolutionary and so massively armed and equipped that the Japanese navy was unprepared to respond at any level—strategic, operational, or tactical. At the end of 1943, this offensive power was turned against Japan’s defensive zone in the Pacific and, over the next six months, overcame or bypassed its island bases one after another.
By the summer of 1944, the Japanese defensive line had failed to hold, and the Combined Fleet, so carefully husbanded for the opportunity to fight the long-sought decisive battle, could no longer muster sufficient strength for a counterattack. By that autumn the Japanese navy was faced with a stark choice: to conserve what remained of the Combined Fleet without confronting the cresting wave of American naval power and thus witness the United States take one Japanese bastion after another, or to throw the fleet in front of the American advance and risk its annihilation. The disasters at the Philippine Sea and Leyte Gulf in 1944 were the consequences of Toyko’s attempts at the second alternative. By May 1945, most ships of the once mighty Combined Fleet had been sunk and its assorted remnants were cowering in the bays and anchorages of the home islands under a rain of American bombs. By the time that the USS Missouri dropped anchor in Tokyo Bay, the cost in Japanese ships and men had been tremendous: 334 warships and well over 300,000 officers and enlisted men.
B. SUMMARY AND ASSESSMENT
The Japanese navy’s conduct of the Pacific War hinged on its strategy, and the most fundamental aspect of that strategy was the disconnection between the war that the navy planned for and the war that the navy initiated. As a continent-oriented force for most of its existence, it was used to thinking in regional and limited terms. Its successes in the Sino- and Russo-Japanese wars had been waged against regional foes and in carefully limited theaters of operation. In plotting the opening moves of the Pacific War, the Navy General Staff may have believed it was planning for a limited conflict, but by its surprise attack on Pearl Harbor it created a political, psychological, and strategic climate in the United States that made total war inevitable.
Cocooned in self-confidence, the Japanese naval high command also mistakenly assumed that it would be able to determine the pace as well as the direction of the war. But after 1942, the navy became increasingly frustrated by the growing ability of the American enemy to move farther, faster, and with greater force, as well as by the navy’s own inability to prevent the enemy’s strategic moves.
Moreover, the Japanese navy failed to think through what was entailed in the second phase of its strategy because it failed to appreciate the vast size of the arena it had chosen to defend. The navy’s strategy of trying to defend a chain of widely separated island bastions with locally deployed air units was basically unsound. The navy simply lacked the means to hold such front-line positions in depth or the strength to support those forces committed to that defense.
As late as mid-1944, the Japanese navy still counted on a single great naval victory to turn the war around. Other elements of sea power—including convoy protection and antisubmarine warfare capabilities—were often sacrificed to this concept. The navy’s dogged pursuit of this chimera not only warped its force structure, it also limited its chances for success in several major engagements it did fight. Indeed, the abject demise of both the Musashi and the Yamato under aerial bombardment without having fired a shell at a worthy target demonstrates the futility of the decisive battle idea. It also exemplifies the navy’s failure to think of alternatives.
If the Japanese navy vainly chased the chimera of decisive battle across the Pacific until late in the Pacific War, early on it was forced to confront the reality of attrition. During the conflict, attrition—that is, attacks from submarines and aircraft other than those in a major named engagement—was the cause of the destruction of the Japanese merchant marine. Here the Japanese navy was slow to adjust to the mounting danger. In the first year of the war, while America’s submarine operations were still limited by technological, tactical, and command problems, the Japanese navy did little to strengthen its ASW capabilities. The 900,000 tons of Japanese shipping sunk in 1942 should have been a warning. By the beginning of 1944, when American submarines were scouring the west Pacific in great numbers, the situation was too late to reverse. At war’s end, Japan had only 1.5 million tons of merchant shipping left out of a prewar total of 6.4 million tons. But attrition also accounted for nearly half the navy’s losses in surface warships.
If American submarines were initially hampered by a range of technological problems, their Japanese counterparts were tethered by an ineffectual doctrine. Focused on fleet operations, their commanders’ failure to attack American troop and supply ships was a major oversight because such operations, pressed home aggressively, would have enormously complicated Allied counteroffensives during the middle and later stages of the war.
No aspect of the Japanese navy’s prosecution of the war was more wasteful of its energies and resources than the interservice feud endemic to both services since the early years of the twentieth century. The services’ latent distrust of each other turned to active hostility as the war situation worsened. It inhibited overall strategic planning, it often hindered operations, and it resulted in tremendous duplication of effort in the development and production of technology.
If the weak point of the Japanese navy in World War II was strategy, its strength was tactics. During the first two years of the war, the navy frequently showed itself the tactical superior of its American enemy. After that, no matter how well or poorly the navy conducted its battles, the overwhelming might of American sea power made tactics irrelevant in determining the outcome. In the campaigns for the Solomon Islands, one can best evaluate the navy’s tactical performance in a period when Japanese and American naval forces were roughly in balance. In the seven engagements of the campaign (eight, if one divides the night actions off Guadalcanal between the battleship and cruiser engagements), the Japanese were usually able to exchange blow for blow. Four actions (Savo Island, Cape Esperance, the battles off Guadalcanal, and Tassafaronga) were night surface engagements that demonstrated that the Japanese were better prepared for night combat than the Americans were. The Japanese navy’s tactical successes in these engagements were clearly the result not only of the superior professionalism of the Japanese commanders on the spot but also of the navy’s officers and men who, across the board, were intelligent, superbly trained, physically tough, highly motivated, and obedient unto death. No doubt, the navy’s emphasis on seishin (spirit) was a significant element in the capabilities of all branches of the navy.
Although seishin eventually led to dangerous overconfidence and thus contributed to eventual defeat, toward the end of the war, when the navy was shattered, seishin held its remnants together far longer than would have been possible in any other navy faced with similar ruin. In the long run, however, quality in training and morale could not compensate for inadequate quantity worsened by mounting casualties and combat fatigue. This was particularly true in the navy’s air arm, in which, as the ranks of seasoned aircrews thinned rapidly in the last years of the war, large numbers of inadequately trained pilots were rushed into combat with predictably disastrous results.
The tactical schemes of the interwar decades yielded a wide range of results. The navy’s single most impressive tactical innovation in the prewar years was the concentration of carrier air power manifested in the formation of the First Air Fleet, which, when it was formed in April 1941, was the single most powerful agglomeration of naval air power anywhere in the world. But it represented a hit-and-run strike force concept that was soon superseded by the American task force—a multicomponent fleet supplied by a mobile fleet train and able to provide round-the-clock offensive operations against a target. Some tactical innovations studied and practiced by the navy in the prewar years were employed, at least for a while, with reasonable success. In particular, night combat tactics and technologies (particularly Japanese optics) were quite effective in the early battles in the southwest Pacific. Others were far less successful. The midget submarine idea proved to be a bust, as did plans to use submarine-launched aircraft for reconnaissance and long-distance concealed firing by the navy’s surface torpedo units. The merits of “outranging” are hard to judge. Although the Japanese navy’s long-sought apotheosis, the great gun duel between Yamato-class battleships and the American battle line, never took place, the idea—embedded in the design of a variety of Japanese weapons, ships, and aircraft—was sound enough. But often the Japanese ability to outrange the enemy was simply vitiated by ineffective Japanese strategy, as in the case of Japanese submarine doctrine.
Given the ultimate scale of the American superiority in industrial power and the utter annihilation of the Combined Fleet by war’s end, it is clear that Japan was doomed to defeat and that, after 1943, there was little the nation and the navy could have done to avoid that defeat. Yet various strategic and doctrinal decisions not taken could have improved the odds for the navy and could have prolonged the struggle. Several examples come to mind. As discussed earlier, the surprise attack at Pearl Harbor was of questionable strategic value. If the navy had paid greater attention to the vulnerability of the home islands and of Japan’s commerce and communications routes to submarine blockade, it would have not been so quickly cut off from its overseas strategic resources. If it had directed its own submarine strategy toward the interdiction of supply and communications routes between the American West Coast and American advance bases in the Pacific, the U.S. amphibious counteroffensive in that ocean might have been seriously delayed.
Yet a balanced view of the Japanese navy’s performance in the Pacific War requires a careful consideration of the first two years of the conflict. During that period, the navy waged the sort of war for which it had planned and trained. If one concentrates on tactical outcomes, the navy’s record is rather good. Excluding both the Pearl Harbor operation and the massacre of a Japanese convoy by U.S. Army Air Corps bombers in the Bismarck Sea, there were seventeen engagements between American and Japanese naval forces during the first two years of the Pacific War. Four were carrier battles, of which the Japanese lost one (Midway) decisively and fought the others to a draw. Of the remaining thirteen ship-to-ship encounters, the Japanese won six; the U.S. Navy, four; and three were draws. That record is proof that when pitted against naval forces also employing tactics and technologies developed between the world wars, the Japanese navy was a formidable fighting force. It was not until the introduction of revolutionary tactics and technologies by the U.S. Navy and the exertion of preponderant American naval power early in 1944 that the tide turned decisively against the Japanese navy.
C. REFLECTIONS ON THE JAPANESE NAVY
When the Japanese navy initiated the Pacific War, it was indeed a formidable fighting force. It comprised 10 battleships, including the first of the 2 greatest battleships ever built; 10 aircraft carriers; 38 cruisers, heavy and light; 112 destroyers; 65 submarines; and numerous auxiliary warships of various sizes. Japanese naval aviation was world-class; its air crews were the best trained and the most experienced. The personnel of the navy, both officers and enlisted men, comprised a professional elite unsurpassed in training, bravery, and dedication. Yet certain strategic, organizational, and technological decisions made by the navy in the interwar period proved fatal. To those decisions should be added certain inherent national impediments, many of which were beyond the navy’s control but which in the end were ruinous to the navy’s prospects in fighting a modern naval war.
It is a stark fact that Japan’s resource base was inadequate not only in terms of the obvious resources of oil and rubber but also in specialized materials such as high-performance metals, which hampered Japanese naval and aviation technology, for example, the production of light-weight but powerful aircraft engines or ship power plants that could handle the highest steam pressures. Japan’s shortage of these resources was worsened by the fact that it had to import most of them from overseas and by the vulnerability of the shipping that brought them to Japanese industry in the home islands.
Japan also entered hostilities with woefully inefficient transportation and distribution systems. The consequence was exemplified by the fact that the first production model of its finest fighter aircraft, the Mitsubishi Zero fighter, was taken by oxcart from the Mitsubishi aircraft factory to the nearest airfield for flight testing. In the latter stages of the Pacific War, the production of small parts for various equipment and weapons was undertaken in hundreds of small workshops scattered throughout the home islands, resulting in colossal inefficiencies in the distribution of raw materials to these mini-factories and in the distribution of the finished products to the naval and air units that needed them.
A crippling disadvantage to the navy in amassing ships, aircraft, and weapons was the fact that Japan operated from a much smaller and temporally shorter base of technological expertise. Whereas the U.S. Navy could call upon a host of private research laboratories as well as its own research facilities, the Japanese navy essentially had to rely on its own technological research centers, which were few in number. This situation was worsened by the fact that the navy had given too little thought to the mobilization of the scientific and industrial assets it did possess and by the duplication of effort and inefficiencies caused by its hostile relations with the army. Japanese failure to keep up with the Western allies in radar is more than partially explained by these deficiencies. A related problem was the inadequate number of naval dockyards in Japan compared to the United States. Japan had far fewer dockyards, both commercial and navy, in its ports.
The consequent disparity in production figures is exemplified by the construction of destroyers in Japan and the United States during World War II: 61 destroyers were built in Japan during 1942–1945, and 354 destroyers were built in the United States during the same period. Part of the problem for the Japanese navy was that there were too few ships of any particular design and too few ships per dockyard. The result was that the Japanese did not develop efficiencies of production as rapidly as their American counterparts did.
Yet it is undeniable that through its understanding and eventual mastery of the basic principles of Western technology, the Japanese navy designed and produced outstanding warships, combat aircraft, and weapons. Among these are the two superbattleships Yamato and Musashi, the Fubuki-class destroyers, the Mitsubishi Zero fighter, the G3M medium bomber, and the Type 93 oxygen torpedo. When introduced, they were worldclass technologies. But they were older, “first generation” technologies that Japan had brought to perfection, and, like all technologies, they were bound to be overtaken by other technologies. Therein lay a serious problem for the Japanese navy. Because of scarce resources and limited facilities for technological innovation, made worse in wartime when Japanese manufacture found it hard just to replace combat losses, it was difficult to develop, test, and produce new weapons and equipment. Even more importantly, the limitations on Japanese science and technology prevented Japan from developing complex and critical “second stage” technologies that were introduced by the United States including radar, the VT (proximity) fuze, and forward-thrown antisubmarine weapons.
Exacerbating these scientific and industrial limitations was a basic defect in the thinking and preparations of both Japanese armed services but particularly in the navy: a fundamental miscalculation of the relationship between strategy, force structure, and the nation’s industrial base. Counting on surprise, speed, and overwhelming fire power, the navy planned for a lightning offensive of war of short duration that would culminate in a single, swift, and annihilating victory.
This assumption led to the design of a small number of superior ships and aircraft whose quality was counted on to defeat a larger number of enemy ships and aircraft of inferior quality. Once the impetus of the navy’s strategic offensive was halted and the conflict turned into a serious war of attrition of men and material, not only did the navy have too little of everything but it also found that its human and technological assets were unsuited for attritional warfare.
There was also another fundamental error in Japanese naval thought: the belief that quality could always overcome quantity. Indeed, one can argue that this belief was one of the most essential principles of Japanese naval doctrine and as such shaped much, if not most, of Japanese naval technology. The design and development of a range of weapons, ships, and aircraft were predicated on the notion that they would be decisively superior to their enemy counterparts. This imbalance between doctrine and technology had evil consequences even before the outbreak of the Pacific War. It could be seen in the extreme demands by the Navy General Staff for certain design specifications relating to armor and fire power that made a number of Japanese warships seriously unstable.
“Quality,” in any event, is a complex proposition. It can be judged in relation to how well a particular system performs one particular function—which was the Japanese approach—or how effectively a system is able to confront a range of problems it might meet—the American approach. Moreover, the Japanese confidence that quality was always preferable to quantity was a dubious assumption from the beginning. In the history of modern war, no conflict was ever won exclusively by technologically superior weapons. Rather, most modern wars have been won by superior planning, organization, logistics, staff work, industrial output, and political leadership. Stalin probably had it right when he pronounced that “quantity has a quality all its own.”
For much of its seventy-five year history, the Japanese navy demonstrated the solid application of scientific methodology to the development of its tactics. In the late nineteenth century, the navy had been at the forefront of tactical innovation. But gradually Japanese doctrinal thought began to atrophy and, by the 1920s, rigidity overtook the navy’s tactical doctrine. By the 1930s that trend had hardened into extreme dogmatism, allowing no criticism of the navy’s orthodox tactical assumptions or consideration of new approaches to naval warfare.
With such a mindset it is not surprising that the navy’s study of naval warfare during World War I focused only on the Battle of Jutland, with little attention given to broader strategic, economic, political, and industrial matters that had in fact marked the margins of victory and defeat. It is obvious that strategy was the Japanese navy’s weakest understanding. In the beginning, at the navy’s genesis, its strategic priority was clear enough: control of the surrounding seas. Its strategic posture was therefore defensive, regional, and limited in scope. Japan’s imperial expansion on the Asian continent complicated this approach, although in its wars with China and Russia, Japan carefully calculated the odds and fought for limited, near-at-hand objectives. But the navy’s support for a permanent Japanese presence on the Asian continent led to a new strategic rationale: projection of national power on the high seas. In turn, this new raison d’être for the navy led to a serious contradiction between regional power, which was attainable, and global reach, which was not.
In the long run, the most critical failing of the Japanese navy was to mistake tactics for strategy, and strategy for the general conduct of modern war. The navy’s over-arching concern was for decisive battle—the one great surface battle on which would ride the fate of the nation. Indeed, it can be argued that in December 1941, the navy was not prepared for war; it prepared for battle. But the idea of decisive battle no longer had much validity in the twentieth century. By then, national destinies were determined not by single encounters but by the strength or weakness of national power beyond pure military might: diplomacy, industrial structure, scientific and technological competence, political leadership, civilian morale, and other elements that had come to comprise total war. The navy gave them little attention—far less, even, than did its sister service. This was due in large part to the dead weight of the Japanese martial tradition with its particular emphasis on “spirit” as equivalent or superior to material assets. Whereas “spirit” accounted for unrivalled bravery by the men who served in the navy, it also led to an arrogance that ignored or discounted enemy capabilities and a blindness to material realities that bordered on the irrational. This, then, was the Imperial Japanese Navy’s ultimate failure to the Japanese nation it served so bravely: the failure to understand and prepare for modern war.
