November 1, a day of strong winds and rough seas, found Yamamoto and his staff aboard Nagato in Tosa Bay off the coast of southern Shikoku, where they observed training maneuvers. At 1630 Yamamoto received an urgent confidential telegram from the Navy Ministry requesting him to come to Shimada’s offical residence at noon on the third and to avoid anyone’s notice.
Curiosity nibbled at Ugaki’s mind all day. Would the Naval General Staff ask how long the Combined Fleet could postpone going to war in case of further negotiations? On that score Ugaki had no doubts. “We, as the Combined Fleet, have reached the following conclusion: 8 December is most preferable in view of completion of preparations, moon age and the day of the week.” Could the summons mean that Yamamoto would become premier and concurrently navy minister? “This would be against his will.”1
Actually a Cabinet crisis was narrowly averted that day. The last of the current liaison conferences had begun at 0900 and continued for about seventeen hours in an atmosphere of angry tension. The upshot of the conference was agreement on war, to begin “in early December,” with negotiations to continue “until 0000 hours, 1 December.” Before that date any clash that erupted as a result of Japan’s air, submarine, and surface movements could be settled as a local incident.2 The meeting also decided that if Proposal A failed, they would offer Washington an alternative, Proposal B:
1. Both Japan and the United States will pledge not to make an armed advance into Southeast Asia and the South Pacific area, except French Indochina.
2. The Japanese and American Governments will cooperate with each other so that the procurement of necessary materials from the Netherlands East Indies will be assured.
3. The Japanese and American Governments will restore trade relations to what they were prior to the freezing of assets. The United States will promise to supply Japan with the petroleum Japan needs.
4. The Government of the United States will not take such actions as may hinder efforts for peace by both Japan and China.3
Rear Admiral Zenshiro Hoshina, chief of the Navy Ministry’s War Mobilization Bureau, tells us that he learned of the Pearl Harbor attack plan at this time and that all members “present at this meeting understood that an attack against the U.S. Fleet would be made as the first step in the coming war with the U.S.”4 On November 5 an imperial conference confirmed the decisions of the liaison conference, already approved at a Cabinet meeting on November 4.5 By now the war-horses had the bits between their teeth and approval was a foregone conclusion.
On board Nagato as she glided into Saeki Bay at 0500 on November 2, Ugaki watched the moon as it “hung on the edge of a mountain . . . as if it had just finished its job.” At 1020 Yamamoto left for Tokyo, leaving his chief of staff in charge. That evening Ugaki received an urgent message from the First Bureau, asking the Combined Fleet’s blessing on a gathering to be held in Tokyo from the eighth to the tenth to reach an “Army and Navy Central Agreement.” Ugaki immediately replied, “No objection.” He entered in his diary: “With this telegram we can see that they have made up their minds at last.”6
He was substantially right. Uchida noted: “In the conference between the Cabinet and the Military General Staffs the decision was reached to fight the war.”7 Nakahara, too, recorded: “it was recently decided that the Government will . . . take positive steps. . . . It came to this: a change in political policy is absolutely necessary from the standpoint of war preparations.”8 No one seemed to note the incongruity of such an idea—like overeating to fit into an outsized shirt. These diarists recorded the decision for war as final, with no diplomatic embellishment and without awaiting imperial sanction.
At 1330 on November 3, Nagumo summoned to Akagi his commanders at each level together with their staffs. He could assemble them rapidly because the previous day, for the first time, all the ships scheduled to be a part of the task force had congregated in Ariake Bay.9 Nagumo had decided that the time had come to inform them of the purpose of their long training.
To the best of his hearers’ recollection, Nagumo said something like this: “Judging from the diplomatic situation, war with the United States seems unavoidable. In that event we plan to attack the American Fleet in Hawaii. Although final details have not been firmed up, Commanders Genda and Fuchida have mapped out a general plan. They will explain it to you. If, after hearing the explanation, you have any questions, feel free to ask them.”10
Oishi explained the overall outline; then Genda presented the air attack plan, Fuchida helping with the details. Some of the airmen almost fell out of their seats in their astonishment. Most of them had realized for some time that their training was aimed at a particular objective and had speculated avidly about Singapore or Manila. “Surely, it’s not Hawaii,” many decided. Now they exulted, “I was born a boy at the right time!”11
A change of pace ensued the next day—a dress rehearsal for Operation Hawaii. Fuchida had scheduled many dry runs during October, originating from land bases instead of carriers to save precious fuel. But this time conditions would be as much like the actual attack as Fuchida could make them. So the task force sailed with most of the aircraft aboard their home carriers to a spot about 200 miles from Saeki. The first wave took off at 0700; the second at 0830 followed the general pattern of a defending force, but the Fifth Carrier Division did not participate.12
About twenty miles from Saeki, Fuchida ordered deployment. At his signal the dive bombers soared to attack level and the torpedo planes sought lower altitude. Below the attacking force the battlewagons of the Japanese Fleet lay in majestic array, just as the planners hoped their counterparts would rest in Pearl Harbor. Aboard ship, officers of the Combined Fleet watched with keen interest, Genda among them. Later he would collect reports from the other staff officers to pass to Fuchida.
After the first wave hit the “enemy,” the second group of level and dive bombers swooped in. No torpedo planes would participate in the second wave because by that time the element of surprise would be lost. This time the high-level planes tore into Saeki Field while the dive bombers concentrated on the ships, particularly Akagi and Soryu.13
By 0930 the maneuver was over. The task force arrived back at Ariake Bay at dark, and Nagumo held a critique aboard Akagi next morning.14 In comparing notes with Genda, Fuchida pointed out that it had taken much too long to rendezvous. Genda was dissatisfied with the approach to the target and general deployment; he handed Fuchida a sheaf of notes to mull over and pass on to the flight leaders. Both Genda and Fuchida, as well as the other knowledgeable observers, worried because only 40 percent of the torpedoes had leveled off at the correct depth. The others had dropped to fifteen or even twenty meters. However, the latter case was rare, and the prospects looked hopeful. Still, the perfectionist Genda was far from satisfied.15
Meanwhile, Commander Joseph Rochefort, at his Combat Intelligence Unit at Pearl Harbor, observed a certain amount of progress. A Japanese-language student and one of the best intelligence experts in the business, Rochefort was hot on the trail of Japan’s carriers. Although unable to decode a good 90 percent of the Japanese naval material channeling through this unit, he and his group could winnow out a considerable amount of information without reading the actual text of the messages.16
Over the years American Combat Intelligence “had developed a pretty fair knowledge of the Japanese naval communication system which involved, among other things, a rather detailed knowledge of the radio circuits. . . .” At Pearl Harbor they covered the circuits which seemed to promise the best results, lacking the manpower to cover all of them.17 Even certain personality factors began to emerge. The radio operator on Akagi, for example, “played that key as if he were sitting on it,” recalled Layton.18
Naval Intelligence on Oahu had been aware for some time that Japan’s carriers were up to something. “The Japanese naval organization was so set up that originally the carriers or carrier divisions had been assigned to both First and Second Fleets,” Layton explained. “Sometime in the middle of 1941 this organization was apparently dissolved. It took us some time to find out for sure. The carriers were lumped in one organization.”19 By coincidence, on November 3 local time, the day of the first full-scale practice for Operation Hawaii, Rochefort’s unit noted a new address which “broke down as ‘ITKOUKUU KANTAI” of which the literal reading would be First Air Fleet. If this were correct, it would suggest “an entirely new organization of the Naval Air Forces. There are other points which indicate that this may be the case.”20 Although Layton, Rochefort, and their men were on the right track, they never imagined that they had spotted the organization which eventually would attack Pearl Harbor.
Yamamoto returned to Akagi at 2145 November 4, Japanese time. He told Ugaki that a decision had been reached: “‘While negotiations will be continued, modifying our demands as much as possible, the Army and Navy will continue war preparations. The final decision will be made by noon sic of 1 December. In case we go to war, it will be some day in early December (the Navy intends to have the 8th as X-Day).’”
Shimada had asked Yamamoto’s opinion on the need for personnel changes in the Combined Fleet. Predictably Yamamoto replied, “Since even one or two reshuffles in the high ranking posts would influence the morale of the whole Fleet, I do not want to see any change at all at this moment.”21 Thus, Yamamoto declined a golden opportunity to replace Nagumo under the guise of a routine personnel reassignment program, had he really desired to do so.
While in Tokyo, Yamamoto had conferred with Nagano. The latter wanted Yamamoto’s reassurance that he would call back Nagumo’s task force if (1) it were spotted; (2) the secret somehow leaked out; or (3) the negotiations succeeded at the last minute. Yamamoto agreed that the Combined Fleet would accept full responsibility for calling back forces deploying before December 1. After that, as he told Nagano, “the situation would be in the lap of the gods.”22
November 5 began auspiciously with the second dress rehearsal for Operation Hawaii. It followed very much the lines of its predecessor, but this time a variation occurred. About eighty miles north of the target area the attackers ran into a group of fighter interceptors, and an air battle took place at about 0900. If Fuchida and his airmen did not achieve surprise in Hawaii, this was what they could expect. The rehearsal ended successfully at 1140. Genda was still not satisfied with the accuracy of the horizontal bombers. He considered that the men had hit a slump, probably caused by overtraining, but this did not concern him nearly so much as the exasperating torpedoes, which still sounded too deeply.23
Fuchida worried about overconcentration on certain ships. A few vessels had been struck again and again with others almost neglected. Poring over his chart, Fuchida found that the outboard ships—that is, those nearest the attackers—received the brunt of the onslaught.24 This would have to be corrected so that they could bomb the inboard vessels as well.
Ugaki had nothing to say about this rehearsal if, indeed, he paid much attention to it. On November 5 the Combined Fleet staff worked hard preparing the Army-Navy agreement and Combined Fleet Operational Order No. 1. The Naval General Staff would issue Navy Order No. 1, with implementing Navy Directive No. 1, the same day. Although the Combined Fleet would not officially receive the latter two for another day or so, Yamamoto knew exactly what they would contain and wanted his own orders issued simultaneously. Navy Order No. 1 was brief and to the point:
By Imperial Order, the Chief of the Naval General Staff orders Yamamoto Commander in Chief of the Combined Fleet as follows:
1. Expecting to go to war with the United States, Britain and The Netherlands early in December for self-preservation and self-defense, the Empire has decided to complete war preparations.
2. The Commander in Chief of the Combined Fleet will carry out the necessary operational preparations.
3. Its details will be directed by the Chief of the Naval General Staff.
Navy Directive No. 1 from the Naval General Staff was more detailed and ordered Yamamoto to take various measures preparatory to combat.25
Aboard Nagato Kuroshima had been working for months on the Combined Fleet’s Operational Order No. 1. Ever since he had seen the Naval General Staff’s original war plan, he thought Yamamoto’s staff should develop an alternative one. Characteristically he brooded over his ideas for weeks before he began to set the order on paper and he started actual work on the project immediately after the September war games in Tokyo. At that point he put his juniors to work on various subsections of the scheme.
Around mid- or late October Kuroshima called in those reports. Then he worked virtually day and night preparing a draft which he showed to Ugaki. The chief of staff asked Kuroshima why he had gone so far in his planning: Indeed, the draft was less an operational order than a full-scale plan of war. Kuroshima explained that he had done this because he believed “an order should be written which would include all potential operations.” He also thought that with time going by so rapidly it was wise to prepare not only an order but a general plan.26
Weather reports indicated that conditions on November 7 might not favor flying, so Yamamoto decided to start early on the sixth for the Army-Navy discussions in Tokyo. He took off with some of his staff officers, who were to confer with the Operations Section of the Naval General Staff on Combined Fleet Operational Order No. 1. He left Ugaki to follow him later. Thus, Yamamoto missed the final dry run of the Pearl Harbor attack.
Because of a dense fog, the force concentrated on Saeki rather than on the ships in harbor. Ugaki wrote approvingly in his diary: “They have made great progress, which promises well for their big success in the near future.”27 As the task force steamed homeward from the launching point, Nagato blinked in Morse code: “The attack was splendid.”28 Genda did not agree. He considered the bombing tests “very poor,” except for those which bombed the ships. “This result was really disheartening,” he recalled.29
While Fuchida put his airmen through their paces, Yamamoto and his staff emplaned at Iwakuni for Tokyo. Kuroshima reread his draft order for the nth time, changing a word here, fixing a phrase there, always seeking perfection. Yamamoto and Watanabe passed the entire three-hour trip bent over the chessboard.30
On November 7, having followed Yamamoto to Tokyo, Ugaki visited the Navy Ministry, where he observed “every branch working hard and aggressively but cheerfully.” Next, Ugaki met with a number of bigwigs of the Naval General Staff. Then he summoned his attendant staff officers to the First Council Room to work on “the final revision to the operational order of the Combined Fleet.”
Combined Fleet Operational Order No. 1 was more than a directive for the tactical employment of Japan’s naval forces; it presented a long-range strategic plan. Phase One called for the conquest and occupation of Japan’s military objectives; Phase Two, for consolidation and defense against counterattack. The 100-page order also covered thousands of details. In brief, Japan’s territorial ambitions demanded simultaneous action in virtually every corner of the Pacific, including the USSR’s Maritime Provinces. Never had any nation envisaged such widespread operations.31
The Combined Fleet document astonished the Operations Section in Tokyo. It went far beyond anything that group had anticipated in case Japan went to war in the spring of 1942. The Combined Fleet staff had virtually completed the order before the First Bureau found out how greatly it differed in scope from the Naval General Staff’s initial instructions. To Miyo the document “was the culmination of Japan’s spirit of the offensive.”
As air officer he took a particular interest in the plan, going over it carefully with Sasaki, Yamamoto’s aviation expert. Miyo had a number of personal objections, the principal one being that it overextended the Japanese Navy to a fearsome extent. Nevertheless, the Operations Section did not object strenuously to Yamamoto’s Combined Fleet order. It did not expect it would ever be implemented in its entirety. In the first place, it far exceeded the capacity of the Combined Fleet; in the second, when it came to launching these grandiose schemes, the Naval General Staff would have the power of veto. Of course, Fukudome and his men should have known that stopping Yamamoto once he was in motion was like trying to hold back the tide.
The conference between the Operations Section and Yamamoto’s staff officers lasted only one day, and publication of the order began immediately thereafter. The Naval General Staff printed it, running off 700 copies—an astounding number for a top secret document—with yeomen from the Combined Fleet doing the job.32 The order originally included the Pearl Harbor project, but this was deleted from the copies and appeared only in the original.33 Fortunately Kusaka recorded for posterity a brief portion in the order pertaining to Operation Hawaii:
1. The Task Force will launch a surprise attack at the outset of war upon the U.S. Pacific Fleet supposed to be in Hawaiian waters, and destroy it.
2. The Task Force will reach the designated stand-by point for the operation in advance.
3. The date of starting the operation is tentatively set forth as December 8, 1941.34
Here in unmistakable terms is the task force’s stated mission: to destroy the U.S. Pacific Fleet. All the thinking, planning, and training in terms of Pearl Harbor were for one reason only: Kimmel’s ships were more likely to be found there than anywhere else.
The Navy Ministry top brass—chiefs of each bureau and department—also met that day, November 7. The Finance Bureau reported a supplementary budget demand, and the conferees agreed that reports on ship locations and the weather should be stopped.35 It was just in time. Rochefort’s Combat Intelligence group had excellent fixes on a number of Japanese units and was moving close to identifying the First Air Fleet. The intelligence summary for November 6 (November 7, Japanese time) noted a sharp tightening of Japanese communications security.36
While the last-minute planning shaped up in Tokyo, operational preparations continued in the First Air Fleet. Shortly after the final rehearsal—on either November 7 or 8—Genda flew from Akagi to Kagoshima to consult with the torpedo pilots in an attempt to solve the remaining difficulties: depth of the torpedo’s initial plunge and percentage of hits.
These men were very discouraged. “All we can do is rely on the bravery of the other bombers,” Murata said glumly. But they plucked up heart and worked out two methods of operation. In the first, at Murata’s suggestion, the plane dropped the missile from twenty meters at 100 knots in level flight. This test used the modified torpedo with the new fin. The second technique, the brainchild of Lieutenant Asao Negishi, called for launch at 100 knots, altitude ten meters, nosing down 11⁄2 degrees. It employed the Model 91-1 weapon because of the shortage of the modified type.
Genda instructed Murata and his men to try out these techniques within the next few days. Then he left for Omura and Sasebo to make further attack preparations. Murata did exactly as Genda directed, and to everyone’s surprise, both methods succeeded beyond hope. Commander Shogo Masuda, commanding officer of Kagoshima Naval Air Base, who was also Akagi’s flight officer, quickly dispatched a triumphant telegram to Nagumo: “Achieved 82 percent hits.”37 This breakthrough occurred on November 11, 12, or 13 because Nagumo received the message at Iwakuni, where he attended a conference on those days.
Jubilation exploded aboard Akagi when those in the know received the results of the torpedo tests. Genda experienced a great surge of relief. He “thanked God” on the spot, emphasizing his belief that “help will come to those who keep up their efforts and devotion to their work.” While the fine record of the horizontal and dive bombers had almost eliminated any possibility of canceling the strike if the torpedo attack failed, this last-minute triumph tied up the remaining operational loose ends.
Although both tests resulted in 82 percent hits, Genda and his fellow planners decided to stay with the first method, the easier to execute. Moreover, its greater speed and altitude would not expose the planes quite so mercilessly to antiaircraft fire. Genda now had no doubt that the venture could be a resounding success if the task force could achieve surprise.38