The introduction early in the twentieth century of wireless communication stands high among factors that have had a revolutionary impact on warfare. By no means least in significance is the negative side of the picture: the inevitable vulnerability to enemy interception and decryption. The introduction and gradual extension during the twenties and thirties of cypher machines greatly increased the difficulties of penetrating the communications of potential or actual opponents. On the other hand, despite moments of doubt, the machines evoked a sense of security that led to a tendency to continue the use of systems that had actually been compromised. Particularly in the case of Germany and Japan, high level messages continued to be sent via compromised devices to the very end of the war.
So sensational was the impact of the revelations of Ultra during 1973-74, that many students of the period for a time tended to regard it as decisive in the war's outcome. In effect Ultra, together with its Pacific counterpart Magic, was described as having won the war. This is a manifest absurdity in the sense that it ignored other factors without which the war could scarcely have been won. On the other hand, one can make a good case for the view that without “special intelligence” the war would have lasted much longer. The cumulative effect of operations which played a considerable part in allied successes contributed much to eventual victory and weighed the scales heavily against the Axis. The following will concentrate on the relation of Ultra and Magic to specific phases and operations of the second world conflict. As with all the essays in the present volume, it will be the general assumption that the course of affairs previous to those under discussion approximated the actual form of developments familiar from the general history of the period.
Before the launching of the Second World War, Britain had been far from the leader of the pack in pursuit of either developing the mechanical devices in the field of wireless communication or penetrating such developments in other capitals. Germany and Japan were far ahead in constructing cypher machines of high quality – especially Germany's Enigma – and Poland, France, and the United States led the field in keeping close tab on the wireless communication systems of the expansionist powers. The British were enabled to make a great surge forward when the Poles, running short of resources to pursue their advanced program of penetrating Germany's machine cyphers, saw nothing for it but to turn over virtually the whole of their astonishing results to Paris and London a mere month before the opening of hostilities in 1939. This unearned windfall has been estimated as putting the British ahead at a single stroke a full two years from where they would otherwise have been.
It was now a matter of making up for lost time. That this was accomplished without stint is in large part the contribution of Winston Churchill. A major center for the decypherment of enemy wireless messages, notably those conveyed by the celebrated Enigma cypher machine, was established at Bletchley Park on the very eve of the war. It developed apace as the conflict intensified, but would never have reached anything like its full compass if Churchill as prime minister had not thrown the full force of his great office and his extraordinary drive and imagination behind it. Without Churchill's personal intervention it is difficult to imagine the Bletchley community of over 7,000 persons and its absolute priority in the selection of personnel. This must be counted among his essential contributions to the eventual defeat of Hitler's Germany.
However great the score by which the western allies ultimately won the intercept race, it was the Germans who not only started well ahead, but maintained a substantial lead until well into the year 1941. The credit for this belongs less to Göring's Research Office (Forschungsamt) with its more than a thousand specialists than to the German Navy's superb B-Service. Together they gave Germany a head start and general lead in the area of wireless communications analysis. In the naval conflict associated with the German seizure of Norway the situation was so one-sided that the British commander in the North Sea complained that he never knew where the German units were, whereas they always seemed to know the location of his own ships.
In France the entire German offensive operation through the Ardennes was predicated on familiarity with the official code by which the Paris War Ministry communicated with its armies and army groups. Yet a single Ultra decrypt of the morning of 23 May largely restored the balance by saving Lord Gort's army from destruction. A signal from Army commander Walther von Brauchitsch to the advancing Army Groups A and B revealed the threatened encirclement of the British forces. The intercept is believed to have been vital in persuading Gort and Churchill to prepare the evacuation of Dunkirk, and thus the saving of an army without which the eventual allied victory over Hitler's Germany would appear inconceivable.
With respect to the Battle of Britain, it was fortunate that the first major breakthrough in solving the Enigma traffic of the period concerned the internal signals of Göring's Luftwaffe. Again and again the general pattern of the German air offensive as well as the size, timing, and targets of individual raids were revealed in time to permit the necessary adjustment of Britain's all too limited air defense. The offensives against the London dock area were known in time to permit the concentration of available fire fighting resources. Thus, whereas no single sensational decrypt can be said to have profoundly influenced the course of events, the sum total of their contributions to British defense is an impressive one. When the balance of forces in the Battle of Britain was poised on the razor's edge, the contribution of Ultra to the British cause deserves to be counted among the factors which in the end assured British victory.
There is much about the “intercept war” in Africa that is as fascinating as it is unique. Aside from the initial phases of the war in 1939-40 it is the sole period of the conflict in which, for a time at least, something like a balance of forces can be said to have existed. A second unique feature that repeatedly and profoundly influenced the course of events was that on both sides the remoteness of the theater from the respective centers of command dictated the widest use of wireless communication, with a corresponding vulnerability that was exploited on both sides. For the Germans the situation meant a virtually full reliance on the Enigma. On the British side the enhanced value of Ultra was for a time paid for by German access to the code in which the American military attaché made daily reports to Washington.
Colonel Frank Bonner Fellers counts among the more extreme Anglophobes the writer encountered during his wartime experience. As he was also the type of person who troubled little to hide such sentiments, his British hosts could scarcely have failed to be fully aware of this. It may well have contributed to efforts to win him over that he was given extraordinary access to information on the daily course of affairs. This he duly reported in the “Black” attaché code which the Italians had purloined from the American embassy in Rome. Although they gave their German allies only the gist of the intercepted messages, this was sufficient to enable the Germans to break the code independently, with enormous benefits to Rommel's command. He was further assisted by a superb field intelligence unit under the talented Captain Alfred Seebohm. Together these two sources of vital information more than compensated for the advantages the British derived from Ultra.
A reversal of fortune that must have hit Rommel like a thunderclap came in July 1942 when an Australian commando raid overran the station of Seebohm's company. The captain was killed and his records seized virtually intact. It spelled the end of the Fellers leak. But before the curtain came down, the Germans had time for a final coup: the waylaying of the plane on which General “Strafer” Gott was coming to take over command of the British Eighth Army in Egypt. Gott was killed and his place taken by Montgomery. Many of Gott's contemporaries believed him to be suffering from burnout. What if Montgomery had never become associated with British operations in Northeast Africa? The course of the war might well have been profoundly affected.
A number of Ultra victories had left major marks upon the confrontation in North Africa before the definitive shift of fortune that marked the late summer of 1942. In this category must be included the Battle of Cape Matapan of 27 March in which the Italian fleet, dispatched to the support of the German invasion of Crete, was once and for all eliminated as a significant factor in the Mediterranean operations. In the land war Ultra was generally successful in the interceptions and decryptions that determined or significantly affected the course of operations. As so often in this phase of the second world conflict, anxiety about security repeatedly hampered fullest exploitation of the medium. It was for example a vital aspect of the fumbling defense of Crete, where preserving the secret originally took precedence over saving the island and its garrison.
The enhancement in the role of Ultra that accompanied the solution of another German army Enigma key in August 1942, virtually coinciding with the coming down of an iron curtain on German intelligence operations, can be classed as the single most decisive factor in the reversal of fortune on the frontiers of Egypt. Montgomery, however false may have been his pose of extraordinary intuition in analyzing the situation, does no doubt deserve credit for his astute exploitation of the opportunities Ultra opened to him. His name is inextricably intertwined with the defeat of the German offensive at Alam Halfa and the following British victory at Alamein. As things were, Alam Halfa in particular was a bitterly contested battle whose outcome was for a time uncertain. Without the benefits of Ultra the possibility of Rommel's reaching the Nile delta is at least arguable.
In connection with both Alam Halfa and Alamein, Ultra was the single most vital factor that led to British victory. The most decisive consequence of the British intercepts was the sinking of virtually all Axis supply ships carrying vital cargoes to Africa-particularly tankers. Rommel's drive into Egypt and his defense at Alamein were crippled by these logistic disasters. With any lesser commander, the similar logistic blows that continued along his flight westward would have meant the obliteration of his retreating forces, even in the context of Montgomery's caution.
Ultra, even when handled with care, was likely to play strange tricks on its usual beneficiaries. The most notorious instance of such a backlash was the American debacle at Kasserine Pass, when Rommel overnight altered his plans and dispositions. The scales more than balanced, however, when Ultra revealed his subsequent shift southeastward to waylay Montgomery as the Eighth Army emerged through the Mareth Line. Two days later the master of desert warfare left Africa for good.
What if Ultra had not been available to the allies in the Sicilian and Italian campaigns?
Aside from its role in keeping track of German reactions to the famed ploy by which a body of a supposed British courier was washed ashore on Spanish territory to divert attention from the approaching invasion of Sicily, Ultra played a comparatively minor role in the campaign on that island. Ultra performed its usual useful service of providing information on pending Axis movements and general order of battle. But it nowhere played a truly significant role in determining the course of operations. When it could have provided vital insight on such Axis moves as those preparatory to the evacuation of Messina, it was largely ignored by the senior Allied commander.
Part of the story involves an excessive concern about security that prevented the passage of vital information to front-line units from fear that their next moves might reveal familiarity with the Enigma messages. In some instances divisional commanders were left in ignorance of major developments on the Axis side of the line. Insofar as the American leadership in Sicily is concerned, General Patton's personal dislike of the British liaison officer attached to his command almost certainly played some part in the small heed which, in contrast to his later direction of affairs in France, he tended to give to Ultra during the campaign in Sicily.
It was only in the concluding phase of the fighting south of Rome that Ultra was able to live up to its full potential in deciding the course of the operations. Yet even before the allied landings at Salerno and at the toe of the Italian boot “special intelligence” proved enormously useful in showing the extent to which such diversionary efforts as Mincemeat (the “courier” corpse) had actually succeeded in tying down German troops elsewhere. Without these diversionary successes the allied situation at Salerno, for example, would have been a relatively hopeless one. If this is so, Ultra may be regarded as decisive in facilitating the landing and subsequent campaign in Italy.
Ultra made another contribution in that it revealed both Hitler's original intention to retire northward and continue fighting in northern Italy, and his subsequent rejection of Rommel's advice in favor of fighting on a strong line south of Rome on the level of Monte Cassino. Every German unit of any significance within or close to Italy was identified. Without the inside information the hazards of a landing on the peninsula would have been increased to a point where the entire enterprise would have become questionable.
Though Ultra continued to supply useful information, the stability of Monte Cassino front did not facilitate major impacts on the course of events during the months that followed. It was in the hope of breaking this deadlock and smoothing the path to Rome that General Alexander, strongly urged by Churchill, decided on the landing at Anzio. The beachhead was to be quickly exploited by a push eastward to the Alban Hills or a drive directly northward to Rome. Yet not only did General Lucas lack driving power in the two unblooded divisions assigned to him and which would have exposed his force to early annihilation. He made no effort to extend the perimeter of the beachhead to a point where German ordinance could not have dominated everything down to the water. What tactical information Ultra provided did save the entire enterprise in that it thwarted the German counterattack (Fischfang, February 1944) that might otherwise have succeeded in throwing the allies back into the sea. Thus, Ultra was a life saver at a critical moment of the campaign in Italy. Anzio can not be spared the label of failed operation. Ultra saved it from being a disaster.
So the virtual freeze of the front south of Rome and Naples continued through the spring of 1944. Then it was Ultra which paced the way north. Exact knowledge of the strength and location of every German unit in Italy facilitated a series of diversionary moves that fixed German strength as much as possible on the east and west coastal areas of the peninsula. Alexander finally initiated a breakthrough in the DIADEM operation not far east of Monte Cassino. The movement was well prepared, smartly executed, and associated with a full bag of deceptions, most of which were directed to attracting attention to the coastal areas. That DIADEM did not bring the war in Italy to a final victorious conclusion was in large part the fault of Mark Clark, whose vainglorious dash toward Rome allowed the German Tenth Army to escape annihilation.
To summarize for the Italian campaign, without Ultra:
(1) the vital landing at Salerno would have been hazardous in the extreme and might well not have been attempted;
(2) the beachhead at Anzio might well have been obliterated in Fischfang (Feb. 1944); and
(3) the breaking of the Monte Cassino line by DIADEM and the thrust of the allies into northern Italy would scarcely have come in the late spring of 1944.
The contest in the Atlantic in the years 1940-43 represents a phase of the war in which Ultra is frequently cited as the single most decisive factor in the allied victory. Air Marshal Sir John Slessor, who is emphatic in denying a major role to the medium in the Battle of Britain, here speaks of it as a “real war winner.”1
Without its betrayal via an Ultra signal of Admiral Lütjens, the Bismarck would almost certainly have escaped to Brest. Thereafter in the maneuvering of allied convoys and German submarine wolfpacks, Ultra was a vital instrument on the allied side. It is no simple matter to allocate credit in allied success among it and the significant development of improved depth charges, D/F (radio direction finding) and the shortwave radar that enabled allied planes to come within easy range of surfacing U-Boats. The single close-to-decisive coup engineered by Ultra was its instrumentality in settling for once and all the dispute between the British Admiralty and its Submarine Tracking Room concerning German access to the code by which directions were conveyed to allied convoys.* Overnight the curtain slammed down on the window which had given Dönitz a full view of convoy movements, obliging him after the unbearable losses of May 1944 (43 U-Boats) to abandon at that critical juncture the contest in the Atlantic. The inability of the Germans further to hold things even in the intercept war also determined the Atlantic contest.
There is considerable argument on how a less total allied victory would have affected their prospects for the invasion a year later. How much further depletion could the ships of the future covering armada have endured before it became prohibitive? Much of the merchant fleet assembled for the enterprise would assuredly have rested on the bottom of the sea, quite possibly leaving too few ships to support the invasion buildup in 1944. In the absence of an invasion a strong Soviet victory drive westward would have determined the war. But instead of ending as they did, somewhere between Berlin and the Elbe, the Soviets might well have extended their hold westward to the Rhine or even the Channel, with consequences for the course of world affairs that would have reached down to the present day.
In our consideration of the role of Ultra in World War II some readers will perceive a gap concerning the impact of Ultra information made available to Moscow by London. Not that individual items or their sum total lacked significance. We know indeed that a mass of Ultra data was transmitted to Moscow from London, that in particular, months of such information was made available before the decisive encounter at Kursk of August 1943. But the Moscow archives have thus far been silent on the reception and exploitation of this information. Until the silence is broken we must confine ourselves to guess and logic, neither of which is much of a guide to an assessment of the true measure in which this aid was accepted and utilized.
For Ultra, as for every program in allied intelligence, 1944 was scheduled to be the payoff year, in which carefully husbanded resources were to be expended freely to determine the conflict for once and all. Considerably more than even the large forces tactically assembled for the enterprise was needed to guarantee a successful landing and firm establishment. German strength, notably well-seasoned mobile divisions, exceeded all that could initially be brought against it. It was correspondingly imperative to divide Hitler's forces between the two areas conceivable for abroad-based invasion, Normandy and the Pas de Calais, if possible with the larger allocation to that which was not to be invaded. Imperative also in this scheme of things was deception concerning the size of the forces assembled in Britain so as to follow the initial landing with a continued threat to the Pas de Calais area.
By far the most decisive feature of this program of deception stemmed from the success, early in 1941, in breaking through the encypherment system employed in the Enigma communications of the Abwehr. In particular the instruction wirelessed to its advance post in Hamburg, from which directions were extended to its agents in Britain, exposed the entire network to British intelligence. It had the consequence of delivering every German agent in Britain to execution, incarceration or conversion. The so-called Double Cross system made the principal figures amenable to doubling of the highest order. The rest is a familiar story of the manipulation of the agents' reports from Britain, which were so managed as to totally deceive the Germans on all that pertained to supposed preparation of the invasion of the continent. Fictional divisions, a fictional army group (FUSAG) under the fictional command of General Patton, fake communications networks, fake staging areas, of which one appeared to point toward Norway, and a mass of other deceptive devices were employed with complete success.
When Ultra after the landing in Normandy revealed that Hitler was being persuaded to shift massive forces from the Pas de Calais to Normandy, he was induced to cancel the move by the report of one of the principal turned agents that the move against the Pas de Calais was imminent.
So the invasion progressed and took its course. Without the Herculean contribution of Ultra it might scarcely have been attempted. Under the best of circumstances it would have been touch-and-go. A final life-saver provided by Ultra in the Normandy campaign was tactical and associated with Mortain, General Bradley's conclusive victory against Hitler's attempt to smash through the comparatively thin American front before Avranches. Had Ultra not revealed the transfer of four armored divisions to that sector, the consequences, notably for General Patton's army advancing into Brittany, could have been serious.
Commencing with the failure of the Falaise pocket to close its grip on the German armies fleeing from the collapsed fronts in Normandy, the remaining history of the war in the west of the continent is speckled with missed opportunities to bring it to a conclusion. There was Falaise itself, with the opportunity lost there to destroy Hitler's forces in France once and for all. There was the almost incredible failure to strike northward immediately after the fall of Antwerp to make sure of the control of the Scheldt estuary. Failure to do so made possible a logistic disaster of gigantic proportions. The whole of the Western Front was in some measure affected, not least the paralysis of Patton's Third Army as it stood poised for its first leap forward into German territory. It has been widely condemned as the worst, least excusable, error on the allied side during World War II, with Montgomery as the principal culprit but some share of the blame going all the way up to Eisenhower. The effort to cross the Rhine at Arnhem (Market Garden) was a disastrously failed enterprise for which a heavy price in lives and prestige was exacted. There was finally the surprise of the allies in the German offensive in the Ardennes. “The Bulge” did turn out a major allied victory, but exacted its own heavy price.
One would be tempted to cry, “Ultra to the rescue,” if the true story did not convincingly demonstrate that in each and every instance, with only the partial exception of the Ardennes, special intelligence had not failed to speak loudly and clearly only to be ignored. Insofar as the situation in the following months is concerned, no poverty of information, but an extraordinary richness characterizes all of them previous to the Ardennes battle.
Contrary to what General Bradley at one point believed or wished to believe, the bulk of fleeing German forces was still in the Falaise pocket and could be further contained. It was simply a matter of Ultra being ignored at the critical juncture.
With respect to Antwerp, where the capable General Horrocks was kept champing at the bit by Montgomery while General von Zangen's 82,000 men were slipping through Walcheren and the Beveland peninsula, the greatest port of Western Europe was immobilized for three months, starving a good part of the entire front and halting in its tracks Patton's Third Army as it was poised to make its first leap into German territory. Meanwhile, Monty's hypnotic gaze was fixed on his cherished project of Market Garden. Yet there can be no real doubt about Ultra's message. It had clearly confirmed information from Dutch resistance elements concerning the two armored divisions refitting in the very area of the intended crossing of the Rhine.
As for Market Garden, Ultra had late but not too late conveyed this information and convinced leading figures of Eisenhower's staff that the project should be halted. Ike himself felt that he could scarcely do this peremptorily after having so often urged Montgomery to show more enterprise. But he did authorize Bedell Smith and Brigadier Young to urge Montgomery to reconsider, only to have their doubts swept airily aside, and the attack launched with its disastrous results.
The story of the role of intelligence in the background of the Ardennes offensive differs in a number of respects. Hitler, in addition to other extraordinary security measures, had decreed a temporary blackout of the use of the Enigma. This alone should have alerted allied intelligence to something extraordinary being planned. Moreover, the Führer had not reached down far enough to alert all smaller units and some use of Enigma was continued. It did not tell much, but truly meticulous analysis would have revealed something.
Moreover, the alert Special Service Officer with U.S. Seventh Army, Donald Bussey, had noted the movement of various smaller German units northward and speculated whether something was being prepared by the Germans on the Ardennes front. He went to alert the G-2 officer of Seventh Army, Colonel Quinn, but was fobbed off with the comment that undoubtedly the information had already been noted by First and Second Army intelligence. In sum, though the message of intelligence on the coming German offensive cannot be described as having been loud and clear, it should have been sufficient to alert its recipients if there had been a listening ear.
It is not easy to explain or even to grasp this staggering series of failures at the operational level to conclude the war months before it was finally brought to a victory. One is forced to reach back to the explanation that over the last decades has been reiterated in many studies of the period – an attack of “victor's disease” so virulent that it swept through the allied leadership in response to the resounding triumph in the fighting in France. Doubts about the eventual outcome of the conflict having been basically resolved, Ultra simply no longer occupied the primary consideration of the allied leadership in the decisions which followed.
This section is inevitably a coda to the discussion of the role of “special intelligence” in Europe. The ultimate discrepancy in the forces available to the combatants made Japan's defeat a matter of “when” rather than “if.” In such a context, Ultra and Magic, the code name for the operation that broke Japan's diplomatic codes, were facilitators rather than enablers. The immensely successful campaign against Japan's merchant fleet, for example, was greatly assisted by the ability to read shipping codes. Submarines could be directed to their targets with a precision that nullified the Pacific's vast expanses. They could also be used economically. Three-boat groupings were the norm, in contrast to the large “wolf packs” Dönitz required in the Atlantic. With Ultra or without it, Japan's neglect of convoy escorts combined with U.S. construction capacity would eventually have achieved the same results.
A similar case can be made for virtually every aspect of Ultra's and Magic's roles in the Pacific theater. Their information on Japanese defense preparations certainly reinforced the decision to use atomic weapons rather than risk invasion. But experience from Guadalcanal to Okinawa certainly provided enough data on Japanese behavior to generate the same decision had no signal intelligence data at all been available. Nevertheless, U.S. successes in breaking Japanese diplomatic and military codes represented both a major intelligence triumph in itself and a significant contribution to the war at tactical and operational levels. Three specific areas stand out.
1) Pearl Harbor: The success of the Japanese attack in the context of U.S. ability to read Japanese mail has generated a virtual cottage industry of conspiracy theorists accusing Roosevelt and Churchill, together or separately, of deliberately withholding from commanders on the spot information that might have averted the disaster. Conspiring to bring a united America into the war is depicted as worth the price of a few thousand lives and a few obsolete battleships. The major specific intelligence problem at Pearl Harbor, however, involved “white noise” – the discrepancy between the amount of information available and the ability to evaluate it accurately. In this sense, the U.S. was the victim of its own success, which allowed the interception and translation of over 7,000 Japanese messages in the six months before the Japanese attack.
A related problem involved the intelligence bureaucracy distributing relevant material to appropriate parties. A corresponding case might be made that absent the information derived from broken codes, Admiral Kimmel and General Short might have trusted more to professional common sense in adjusting to the increasingly tense diplomatic situation. Short would probably have remained more concerned with sabotage than a surprise attack. His aircraft would still have been parked wheel to wheel for security purposes. The Navy would still have suffered from the effects of six months of false alarms that eventually diminished alertness. But without the tempting narcotic of intelligence regularly supplied from Washington, which had to be taken on trust to preserve the secret, the commanders on the spot, both competent officers, might have kept their subordinates sufficiently galvanized to give Nagumo's pilots at least an unpleasant surprise and a bloody nose on that December Sunday morning.
The consequences would probably have been more political and emotional than military. The Japanese attack would still have done significant damage. But American morale would have been higher had the fight been less one-sided. What then? Perhaps a major counterattack into the western Pacific, a larger version of the abortive operation to relieve Wake? Husband Kimmel was no Chester Nimitz. Could he have avoided a Midway in reverse? Perhaps by its involuntary role in an initial defeat, special intelligence contributed to a final victory.
2) Midway: By the spring of 1942, U.S. cryptographers had their credibility at CINCPAC. They had also established the nature of Japan's plan for the Midway operation, including dates, times, and diversionary targets. That plan has so often been criticized as too clever to be wise that it is easy to overlook the high level of probability that without cryptanalysis Nimitz and his subordinates, heavily outnumbered and coming off a virtually-unbroken series of defeats, might well have been drawn into Yamamoto's strategic web. Special intelligence did not win the Battle of Midway. It did contribute to victory by enabling U.S. commanders to focus on winning while fighting at a numerical disadvantage, and by facilitating optimal use of limited physical resources.
In an alternate scenario, Midway could have become a U.S. defeat of sufficient magnitude to delay a U.S. counterattack until new ships came into service and new air groups could have replaced those lost. While a successful invasion of Hawaii remained a remote possibility, the results would certainly have included even more desperate island fighting, Japan would have had time to develop its outlying “barrier” while still possessing the “javelin” of its First Air Fleet. In that context would the U.S. have devoted greater resources to the Pacific at Europe's expense? Or would Roosevelt, King, and MacArthur have bided their time, awaiting the outcome of the Manhattan Project and the development of aircraft with the range to deliver the bombs from Hawaii? Would two nuclear devices have been enough to convince a Japan whose people and leaders might even in 1945 have justifiably regarded time as still on their side? If not, what then? More bombs, with the accompanying risk of the U.S. becoming the major postwar villain once the effects of atomic explosions became known? Or an invasion mounted by armed forces already war-weary and seeking to return home? Unpleasant alternatives certainly – but ones that remain in the realm of speculation.
3) MacArthur's Southwest Pacific Campaign: Douglas MacArthur's return to the Philippines between 1943 and 1945 featured a series of deceptions and maneuvers so universally successful at the operational level that even the general's critics tend to accept them as proof of his military talents. Yet MacArthur's successes depended heavily on Ultra. What might have been the consequences had he been forced to operate without special intelligence? The Southwest Pacific theater ranked above only China-Burma-India on the priority list for resources. As early as December, 1942, Ultra served as a force multiplier by reporting Japanese air deployments to the area, and the routes and schedules of Japanese supply and invasion colonies. Initially U.S. submarines and aircraft were only able to whittle down their enemies. By the time of the Battle of the Bismarck Sea in March, 1943, however, air power alone could destroy whole convoys.
Ultra served MacArthur in other ways as well. It confirmed the effectiveness of the deception campaign that kept Japanese eyes turned away from the 400-mile leap to Aitape and Hollandia in April 1944. It provided information on Japanese reinforcement of the Philippines later in the year. Tactically, Ultra kept MacArthur's forces informed of orders of battle and plans for aerial counterattacks during the Leyte invasion, and even provided the first clear knowledge that the kamikaze attacks involved more than a few desperate pilots acting on their own initiative.
None of these contributions were decisive by themselves. Without Ultra the Americans and Australians would still have made reinforcing Japanese positions in the Southwest Pacific increasingly difficult – but by degrees instead of exponentially. MacArthur would therefore have faced stronger forces, better supported and supplied. Would he have been so successful in finding undefended landing sites? Would his losses have been heavy enough to discredit the concept of a two-pronged strategy in favor of an all-out drive across the Central Pacific? Both scenarios appear plausible. And had they been played out, might not the image of “Dugout Doug” have resurfaced? Might the general even have been relieved of his command – an option certain attractive to the Roosevelt administration, one, in fact, averted only by his developing image as a national hero? Even without such a decision, might MacArthur have been discredited enough to deny him the major post-war roles he played in the Far East? Great events sometimes turn on small ones, as the massive door of a vault depends on a single ball bearing. What if ...?
1 Conversation with Sir John Slessor, 1956.