On November 29 Hull was the only one of the top four in the U.S. government who remained in Washington. Roosevelt had gone to Warm Springs, Georgia; Stimson and Knox had flown to Philadelphia that morning to attend the Army-Navy football game. In the late afternoon Hull received some inflammatory extracts of a speech Tojo was supposed to have delivered on November 30 (Japan time). After consulting with his Far Eastern experts and the “military authorities,” Hull telephoned the President. He stressed “the imminent danger of a Japanese attack and advised him to advance the date of his return to Washington.” Roosevelt agreed to come back on December 1.1
Rather more to the point were two significant espionage messages which the Foreign Ministry sent out on November 29. The San Francisco consulate received directions to make full reports beginning December 1 of the name, nationality, port of departure, port of destination, departure date, and so forth “in detail, of all foreign commercial and war ships now in the Pacific, Indian Ocean, and South China Sea.”2 This was certainly a comprehensive order, but quite understandable, for, among other things, Tokyo urgently wished to know whether any foreign vessels leaving San Francisco might sail within sight of Nagumo’s task force. The Japanese were also interested in ships which might get in the way of the Southern Operation.
Of even more direct import was the dispatch sent to Kita: “We have been receiving reports from you on ship movements, but in future will you also report even when there are no movements.”3 Here was another telltale signpost on the road of Japanese naval espionage. The mice need not leave their hole to interest the cat. The U.S. Navy translated this on December 5, so it had two days to make something of it. As in the “bomb plot” message of September 24, this gave another clear indication that at Honolulu the Japanese concern centered in the ships in harbor no less—if indeed not more—than in their comings and goings.
Since his brief visit with Yoshikawa in the backyard of his home in late October, Kuehn, the sleeper spy,* had not been idle on Oahu. Although not supposed to take an active part in Japanese prewar espionage in Hawaii, sometime in either late October or November Kuehn prepared “a plan for transmittal of information relative to the United States Fleet.” On or about November 28 he made a trip to the navy yard, obviously to check on Kimmel’s ships. And around the thirtieth, he went to the Japanese consulate to deliver his plan (or code) to Okuda “relative to the movements and position of the several units of the United States Fleet.”4
Such activity at this time directly violated Kuehn’s contract with the Japanese Navy. It also ignored the instructions which a member of the Tatuta Maru mission brought to Kita from Ogawa and Yamaguchi of Naval Intelligence, charging Kita that he must (1) have Kuehn stop contacting the consulate; (2) tell Kuehn that his code was too complicated and must be simplified; and (3) instruct Kuehn not to engage in any intelligence activities before the outbreak of war.5 Kuehn’s bumbling into the delicate machinery of prewar espionage must have annoyed and worried the consulate. Why Kuehn, a person fairly well known in Honolulu and a property holder on Oahu, should jump the gun on his spying is strange indeed. He testified that either he or Kita suggested that Kuehn scout the U.S. Pacific Fleet.6 It is difficult to believe that Kita did so because it directly contravened Tokyo’s orders concerning Kuehn’s utilization and does not align with the caution the consulate had insisted upon.
Some disagreement exists about the genesis of Kuehn’s code. Kuehn testified that he prepared it in late November,7 while Yoshikawa stated that Kita showed it to him soon after his visit to Kuehn in October.8 The latter is probably correct because the order to simplify the code seems to have come with the Tatuta Maru.9 It is unlikely that Kita, Okuda, or Yoshikawa had any hand in it because the code was typically Teutonic in its overelaboration, superabundance of detail, organization refined to chaos, and disregard of the human element. Yoshikawa considered it primitive and dangerous.10
As one might expect, the consulate told Kuehn that his system was too complicated. He therefore went home and reworked his plan for three days. Then he returned (probably on December 2) and gave Okuda an envelope containing the code, together with $500 for transmittal to his stepson in Germany. He also arranged for various other means of clandestine communications, such as radio station KGMB want ads and use of a boat with a star on its sail. This envelope included the information that seven battleships, six cruisers, two aircraft carriers, forty destroyers and twenty-seven submarines, “or some similar figure,” lay in Hawaiian waters. As he later admitted, “those figures were purely fictitious, as far as I knew.”11
The consulate must have wondered whom Kuehn thought he was fooling, for Kita and Okuda knew from Yoshikawa’s and Kotoshirodo’s reports how many ships lay in Pearl Harbor in late November. Certainly not forty destroyers and twenty-seven submarines—more than Kimmel had in the entire central Pacific—with an extra carrier tossed in for good measure, Enterprise having left harbor early on the twenty-eighth.12
In Washington on November 29, G-2 prepared its “Periodic Estimate of the Situation,” projecting from December 1, 1941, to March 31, 1942. The report contained not the faintest hint that Japan might strike the U.S. Pacific Fleet in Pearl Harbor.13 Nevertheless, Colonel Bratton recalled:
. . . those of us in the Army who were studying this situation always listed, mentally at least, an attack on Hawaii as a capability, but in our discussions of the situation with our counterparts in the Navy it was always emphasized by the latter that their forces in the Pacific were alert and so stationed as to make such a Japanese attack impracticable or suicidal, and we therefore relegated such an attack to the realm of remote possibility.14
Miles, too, observed, “We had spent several hundred million in defense of Hawaii, we had our greatest fleet out there. That Hawaii could be attacked if Japan went to war was obvious to everyone.”15 He also testified:
Of course we had had information for a great many years which had been considered in all our war plans in Hawaii that there was a certain part of the Pacific Ocean that we called the “Vacant Sea” in which there are practically no ships and in which large movements of ships could occur without anybody seeing them. It was that part of the ocean between the great southern routes that go from Hawaii to the coast of Japan and China, and the northern great circle routes that go near the Aleutians.16
That was exactly the area through which Nagumo’s ships were sailing on the very day Miles’s office prepared the report. What is more, G-2 had no illusions that Grew and his attachés in Tokyo could tip them off if a Japanese fleet left Japan. Said Miles: “. . . we never dreamed that we could rely on getting that information. It would have been almost a military intelligence miracle had we been able to spot a task force in forming and have known before it sailed where it was going.”17
So Rochefort and his devoted workers in Combat Intelligence strained every nerve to keep track of Japanese ship movements. On November 27 his summary indicated: “No further information on the presence of Carrier Division Five in the Mandates.” The same report advised: “Carriers are still located in home waters. . . ,” so Japanese deception tactics continued to work effectively. The next day Rochefort had a disturbing development to note: “As has been previously reported the suspected [Japanese] Radio Intelligence net is very active and is becoming more so. . . . This activity is interpreted to indicate that the R.I. net is operating at full strength upon U.S. Naval Communications and IS GETTING RESULTS [Rochefort’s capitals].”18
Rochefort’s report was entirely accurate. From many interceptor stations the Fourth Department of the Naval General Staff monitored American naval radio traffic. It could tell, for instance, when Pearl Harbor signaled a battleship or when Kimmel’s ships flashed Pearl Harbor. Sometimes it could estimate approximate locations, but not often. Japanese radio Intelligence was in much the same situation as Rochefort; that is, it could not decipher the contents of the messages it monitored and had to work from call signals alone. The two radio interception nets were like two warriors playing a deadly game of blindman’s buff, groping for each other by sounds in the vast darkness of the Pacific. The Japanese divided American naval messages into three categories: Urgent, Ordinary, and Meteorological. The Naval General Staff kept a statistical record of all these messages, grouping them according to their importance and number. In this way it attempted to judge the scope of American fleet activity. The United States changed call signals from time to time. For several days thereafter the Japanese would be confused, but by hard work they solved the new patterns. However, after Pearl Harbor the U.S. Navy devised systems which made it extremely difficult for the Japanese even to break the call signals.19
Rochefort advised on November 29: “The HIYEI sic [Rochefort’s capitals] sent one message to the Chief of Staff Third Fleet.”20 Obviously this was part of the Japanese smoke screen to conceal the movements of Nagumo’s ships because at that very moment Hiei was en route to Pearl Harbor.
Communications Intelligence reported on November 30:
Todays sic traffic consisted largely of despatches bearing old dates, some as far back as 28 November. No reason can be given for the retransmission of these messages unless the high volume of traffic for past few days has prevented the repetition of despatches. . . . The only tactical circuit heard today was one with AKAGI and several MARUS [Rochefort’s capitals]. . . .
The Japanese repeated old messages to confuse the Americans. In this day’s batch Rochefort’s men identified Kongo and Hiei as being with the Second Fleet—the first correctly, the latter off the beam by many a mile.21
When Layton brought Kimmel this particular summary, the admiral noted the Akagi-Marus exchange and asked what Layton thought about it. Layton replied that Akagi was perhaps talking to some tankers “and probably going to get oil.”22 Of course, any talking Akagi did to her Marus was by signal flag or short-range blinker.
As Nagumo’s First Air Fleet ended its fourth day sailing through the “vacant sea,” the diarist Chigusa glanced at the calendar and wrote:
At last today is the final day of November. Through the night we operated searchlights and deck lights because of the heavy fog to guard against collision. . . . This afternoon I navigated the ship and we refueled astern very slowly. The towing line broke. Very dangerous but fortunately no injuries. We tried again to refuel but it became dark and we gave up refueling. Our task force proceeds on course at 14 knots.
The nearer they came to Hawaii, the more uneasy Yoshioka became. Genda’s assistant believed this same opportunity would never occur again. But he worried about being sighted by an American submarine or possibly a Soviet ship, and there was the possibility of the massive Southern Expeditionary Force’s being spotted with the United States consequently increasing its patrols around Oahu.23
Genda was considerably less placid than his surface air would indicate. At times he was unusually silent and thoughtful. He noted that at his temples there had begun to appear a sprinkling of white hairs, which he attributed to his intensive work and worry.24 Basically he had great confidence in the power and destructive ability of Japan’s naval air arm. And he retained an abiding faith in himself, in Fuchida, in their airmen, and in their plans. Still, the realization of what lay ahead sometimes jerked him up sharply. At such moments he would stare out across the trackless Pacific and think: Now we are advancing toward Pearl Harbor, not in a dream but in reality. May God help us!25
Genda knew that Nagumo and Kusaka had already decided on one attack. So at every chance he urged Nagumo to keep his mind open, to remain flexible in his approach to the operation, and, above all, to launch repeated attacks. Hit the enemy again and again until he lay utterly helpless, no longer a naval threat to Japan. Time and again Genda beseeched Nagumo: Perform the unexpected, and go all out in the performance. But his words fell on stony ground. Nagumo consistently replied, “One attack only! One attack only!”26
Yet hoping and praying that the situation on Oahu would prove ripe for repeated attacks after completion of the two-wave assault, Genda prepared plans to help convince Nagumo to take any tide of good fortune at the flood and ride it to total victory. It would not be easy to open the door of the admiral’s closed mind, but he could at least drive in a wedge in the hope that it would swing wide with the wind of success. His fertile mind devised four plans, any one of which he hoped Nagumo would put in operation if the airmen succeeded in their initial two-wave attack:
Plan I. Remain in the area about 200 miles north of Oahu for several days after the attack and exploit whatever situation arose. This might call for aerial searches to find and destroy U.S. fleet units not at Pearl Harbor. Or deliver repeated attacks against the remaining ships in Pearl Harbor as well as its installations. Then, satisfied that they had completed all possible damage, return to Japan via the far northern route that Nagumo had already chosen for his homeward voyage.
Plan II. In general the same plan as No. I, but return to Japan on a route not as far north as the one Nagumo had selected.
Plan III. The same as Nos. I and II, but return to Japan along the Hawaiian chain, passing only a short distance north of Midway. This would enable the task force to attack whatever U.S. Fleet units might be sailing in or near that area.
Plan IV. The same as the others, but return to Japan by sailing southward, passing Oahu on the west en route to the Marshalls. Genda considered this his best plan, for it would enable Nagumo to launch a second two-wave assault against Pearl Harbor or Kimmel’s ships at sea on Sunday, December 7 (local time). Then, too, such a plan would allow Nagumo to launch repeated attacks against Oahu as the task force moved southward within easy striking distance of U.S. targets on Monday, Tuesday, or Wednesday of that week. Genda hoped that if Nagumo operated according to this plan—all else being equal—the Japanese could destroy the U.S. Pacific Fleet and put themselves in a position to take the Hawaiian Islands.27
“The most difficult and most agonizing period for every officer in the Naval General Staff who knew about Pearl Harbor.” Thus Tomioka characterized the span of time as the task force sailed the “vacant sea” from November 26 to December 8. He and his colleagues had never been enthusiastic about Yamamoto’s risky venture, and they did not change their minds now. Many still cherished a faint hope that diplomacy might succeed even at the last minute. But they could do nothing about that.
From the day Nagumo’s task force left Hitokappu Bay, Tomioka’s Operations Section stayed open all night. He arose early every morning and worked late. Convinced that the task force would be discovered the day of the attack, if not before, he worried constantly about those precious carriers. He prayed fervently to the gods to grant Nagumo’s ships a safe voyage. But if anything unusual developed, the Naval General Staff intended to order the task force to return at once.28 “The general attitude was to take no more chances than absolutely necessary,” said Fukudome. “If there were any element of doubt or if things did not develop according to plan, the main objective was to get the task force home.”29 Tomioka and his officers kept a chart of Nagumo’s estimated progress. Thus, on November 30 they could see that the task force had traveled more than one-third the distance to Hawaii. So far so good!
Although he and his colleagues could not intervene with Providence on Nagumo’s behalf, they carried out their duties with their usual brisk efficiency. Every morning someone from the Meteorological Section of the Navy Ministry’s Hydrographic Department briefed the Operations Section of the Naval General Staff on the weather in the Pacific. On the basis of these reports Tomioka and Miyo prepared daily forecasts, which were radioed to the task force. For obvious reasons these began two weeks before Nagumo’s ships left Japan.30
To make the communications system more precise, the Naval General Staff gave every coded message a special number after the task force left Hitokappu Bay. And they repeated each of these messages several times to make sure that Nagumo received them, for it was absolutely imperative that he miss none of these dispatches, particularly one that might call his ships back or alert him to potential danger.
As double insurance, the Naval General Staff sent Nagumo a coded message every odd-numbered hour day and night during the voyage. For example, Message No. 13 would be sent at 0900 on December 1. Tokyo would repeat this at 1100, 1300, 1500, and so on through the day, unless newer information made it necessary to send a different dispatch.31 All ships in the task force were required to receive messages from Japan, but Hiei and Kirishima had the most powerful receiving gear. So Hiei was responsible for monitoring all messages to the task force, relaying them to Akagi.32
Another system of conveying information to the First Air Fleet was by regular government broadcasts over Radio Tokyo. These were the routine transmissions which Japan sent several times daily to Japanese residents abroad. For the benefit of the task force, the Naval General Staff arranged to add an extra statement or two at the end of every broadcast, and in this way Nagumo received some of his weather reports. As noted, the task force maintained strict radio silence. Nagumo had authority to communicate with Tokyo in case of an accident, using a special call signal to disguise his sending vessel as a merchantman. As soon as Tokyo received this message, it would repeat it back to the task force so that Nagumo need not signal again. On the return voyage Nagumo could begin communicating with Tokyo once he passed beyond 800 miles from Oahu.33
Across the globe, on November 30 that eager Germanophile Ambassador Oshima met with Ribbentrop at the latter’s request. Ribbentrop urged that now was the time for Japan to fight Britain and the United States. He made a definite commitment: “Should Japan become engaged in a war against the United States Germany, of course, would join the war immediately. There is absolutely no possibility of Germany’s entering into a separate peace with the United States under such circumstances. The Fuehrer is determined on that point.”34
The Americans translated their interception of Oshima’s report to Tokyo on December 1. Kramer of ONI, on loan to Naval Communications, noted that it was the first time during 1941 that the Japanese “had opened up on the subject and progress of these negotiations to the Germans, their allies.”35
The same day Togo advised Oshima that the conversations with the United States “in spite of the sincere efforts of the Imperial Government, now stand ruptured—broken. . . . In the face of this, our Empire faces a grave situation and must act with determination. . . .” Togo therefore instructed Oshima to interview Hitler and Ribbentrop:
. . . Say very secretly to them that there is extreme danger that war may suddenly break out between the Anglo-Saxon nations and Japan through some clash of arms and add that the time of the breaking out of this war may come quicker than anyone dreams. . . .
Say that by our present moves southward we do not mean to relax our pressure against the Soviet and that if Russia joins hands tighter with England and the United States and resists us with hostilities, we are ready to turn upon her with all our might; however, right now, it is to our advantage to stress the south. . . . 36
When McCollum read this dispatch, it impressed him “as being a Japanese excuse to the Germans not to jump on the Russians”; nevertheless, he was convinced that the situation between the United States and Japan was “intensely acute.”37
In London, Churchill had not yet seen these ominous messages because of the usual two- or three-day time lag between London and Washington on Magic. On November 30 he suggested to Roosevelt that they make another effort to avert war between their two countries and Japan by means of “a plain declaration . . . that any further act of aggression by Japan will lead immediately to the gravest consequences.” He promised that Britain would either “make a similar declaration or share in a joint declaration.” He closed: “Forgive me, my dear friend, for presuming to press such a course upon you, but I am convinced that it might make all the difference and prevent a melancholy extension of the war.”38
The Imperial Palace experienced a brief detour on the road to war on November 30. Fate seemed to be offering Hirohito an opportunity to prove that his reign deserved the name of Enlightened Peace. At 1530 the Emperor sent for Kido. “His Imperial Highness the Prince Takamatsu came up to see me this morning,” His Majesty informed his devoted chamberlain, “and told me that as the navy had been fully occupied after all and it appeared to have been disposed to avoid war with America if possible what on earth was the real intention in this regard?”39
From the phraseology it appears that the Emperor was either angry or perplexed, or both. The Navy had been giving the impression that it was opposed to war with the United States. Now, within a week after having been appointed to the Operations Section of the Naval General Staff, Prince Takamatsu had informed his august brother that the Navy had been preparing for war all along. Some of his fellow officers believe that His Highness, knowing that the Navy had no real confidence in victory, advised the Emperor on this occasion not to go to war.40 By this time every member of the Operations Section knew about Pearl Harbor, and to function effectively as a member of that elite organization, His Highness would have to have known also.
In any case, Kido respectfully recommended that Hirohito send for Tojo, Shimada, and Nagano to clarify the matter. Immediately after this talk Tojo arrived, and after him Shimada and Nagano. According to Shimada, “The Navy was never confident of achieving victory over the United States but we were confident that we were better prepared at that time to fight than we would have been at any later date. . . . Admiral Nagano and I on November 30 told the Emperor that the Navy had made adequate preparations.” Indeed it had! At 1835 the Emperor summoned Kido again, to inform him that Shimada and Nagano had answered his question “with considerable confidence, so instruct Tojo to proceed as prearranged.” Kido telephoned this order to the premier at once.41 The green light flashed on once again.