For Kimmel, that weekend brought a certain letdown. “The few days’ stated by the Navy Department on November 27 to be the time for an aggressive move by Japan went by without event.” The discussions which Washington had “stated to be terminated . . . with the barest possibility of resumption, were in fact resumed. . . .” His superiors did not advise him what the State, War, and Navy departments knew through Magic—“that the resumption of negotiations was a Japanese trick. . . .” Therefore, the press and radio reports of developments on the diplomatic front suggested to Kimmel “a mitigation of the emergency which prompted the so-called ‘warning.’”1 Either Kimmel was reading the newspapers very superficially or, like so many American leaders in the autumn of 1941, he was clutching at straws.
Layton “couldn’t understand why Washington didn’t give us more information, but presumed that perhaps they didn’t have it.” This “was a source of considerable concern” to both him and Rochefort. The two officers remained glued to their telephones over the weekend, although Layton returned to his office on Sunday to confer with Kimmel.2
The night of November 30–December 1 brought a highly significant development. The Fourteenth Naval District’s “Communications Intelligence Summary” for December 1 told the story:
All service radio calls of [Japanese] forces afloat changed promptly at 0000, 1 December. Previously, service calls changed after a period of six months or more. Calls were last changed on 1 November, 1941. The fact that service calls lasted only one month indicate sic an additional progressive step in preparing for active operations on a large scale. . . . It appears that the Japanese Navy is adopting more and more security provisions . . . prior to 0000, 1 December . . . an effort was made to deliver all dispatches using old calls so that promptly with the change of calls, there would be a minimum of undelivered dispatches and consequent confusion and compromises. Either that or the large number of old messages may have been used to pad the total volume and make it appear as if nothing unusual was pending. . . . 3
In all of Rochefort’s experience, this was the first time the Japanese had changed call signs twice in a thirty-day period.4 The event had its impact in Washington, too. Turner regarded the change, along with the marked drop in radio traffic, as “extremely significant that very important operations were contemplated, and it was probable that nearly the entire Japanese Fleet had put to sea. . . .”5 In contrast, Wilkinson seems to have regarded the event as just one more indication that “there was an emergency situation arising.”6
Layton considered the call sign change “rather ominous” and anticipated the inevitable “lack of identifiable traffic.” He knew that a drop in volume did not necessarily “indicate an immediate move but it fitted very well with the picture of the southern movement. . . .”7 According to Rochefort, “There was great unease in all of our minds because of the lack of traffic.”8 That included Kimmel, who underlined that portion of the “Communications Intelligence Summary” when he received it. The admiral asked Layton to prepare a paper showing the approximate locations of Japanese fleet units. Layton immediately did so, depending principally upon Communications Intelligence. He delivered it to Kimmel on December 2.9
Layton listed neither Carrier Division One nor Two “because neither one of those commands had appeared in traffic for fully 15 and possibly 25 days. . . .”10 Kimmel promptly pounced upon this omission. “What! You don’t know where Carrier Division 1 and Carrier Division 2 are?”
“No, sir, I do not,” replied Layton. “I think they are in home waters but I do not know where they are. The rest of these units, I feel pretty confident of their locations.”
Thereupon Kimmel turned his ice blue gaze upon Layton. With “somewhat a stern countenance and yet partially with a twinkle in his eye,” he demanded, “Do you mean to say that they could be rounding Diamond Head and you wouldn’t know it?” To this Layton could only answer lamely, “I hope they would be sighted before now.”11
That “twinkle in his eye” haunted Kimmel for years because various Pearl Harbor investigators apparently regarded it as a sign of undue levity in a serious situation. This was certainly not the case. Kimmel had a picturesque way of expressing himself to emphasize a point. Layton was uncomfortably aware that far from joking, his chief was impressing upon him the fact that he did not know the location of four Japanese flattops.12
The admiral was “very much interested” in the whereabouts of these ships. He believed that if the Americans could locate them, he “would be able to determine pretty closely where the main Japanese effort was going to be.” But he thought that postattack references to the “lost carriers” did not quite fit the situation. “As far as we were concerned the carriers were never lost. . . . We did not even know we had lost them. We could not identify them.”13
They might not even be on radio silence. They might simply be part of the unidentified traffic, which included the major part of the Combined Fleet. The change had involved at least 15,000 call signs. As of December 2, when Layton made his presentation to Kimmel, somewhat over 200 had been partially identified, but the carriers did not fall in that 11⁄3 percent.14 Moreover, the Japanese flattops had frequently disappeared into a void. Kimmel testified that in the six months before the attack “there existed a total of 134 days—in 12 separate periods—each ranging from 9 to 22 days, when the location of the Japanese carriers from radio traffic analysis was uncertain.”15
Yet no one took the situation complacently. In Layton’s graphic description, the Japanese “were showing all the symptoms of taking increased radio security . . . they were using multiple addresses and blanket coverage and what we call addressed to nobody from nobody, which everybody copied, and when they do that nobody is being talked to that you can identify. . .”16 He felt extremely apprehensive because the Japanese Navy seemed to be lining up for a major offensive and he, the intelligence officer with the duty “to keep track of the Japanese naval forces,” had found no trace of the carriers except Division Three and sometimes Four.17 Carrier Division Three (Hosho and Zuiho) was with Yamamoto’s Main Body in the Inland Sea, Carrier Division Four (Ryujo) with Takagi’s Southern Philippine Support Force then en route to Palau.
In Washington McCollum’s office took due note of the change in call signs. His estimate for December 1, as usual, attempted to locate major Japanese fleet units. This day’s report placed Hiei near Sasebo and Kirishima near Kure, with Akagi and Kaga in southern Kyushu and the remaining four of Nagumo’s carriers at Kure.18
This was but a part of a very long memorandum which McCollum drafted the preceding Friday and Saturday, covering the full sweep of the worldwide intelligence picture.19 Early on Monday, December 1, he “polished it up in some aspects” and took the memo to Wilkinson. Later that morning McCollum accompanied his chief to Stark’s office, where Ingersoll, Turner, and “one or two other flag officers” had also gathered. Copies were distributed to everyone present; then McCollum read the memorandum aloud. In the discussion which followed, he expressed his opinion that “war or rupture of diplomatic relations was imminent” and asked “whether or not the fleets in the Pacific had been adequately alerted.” Both Stark and Turner gave him “categorical assurance . . . that dispatches fully alerting the fleets and putting them on a war basis had been sent.”20
The DIO’s telephone tap on the Japanese consulate picked up on December 1 a conversation between Lawrence K. Nakatsuka of the Honolulu Star-Bulletin and an individual DIO termed “XX.” From all indications “XX” was Okuda. Nakatsuka called to ask if the consulate had any information about an Asahi newspaper item which he had received through an Associated Press dispatch concerning the closing of Japanese consulates. But “XX” was “his usual blank self.”21
Kita and Okuda may have known—indeed, almost certainly knew—much more than they could tip off to any reporter. The desk pad entry for the day contained the cryptic words “Within the predictable future.”22 Someone frequently jotted down on the pad odd little phrases which seem to reflect nothing more sinister than Kita or Okuda adding to their English vocabularies, but this remark was much too pat for coincidence. Whether they had in mind the date they could expect the “winds” broadcast, or whether they actually meant that the attack on Pearl Harbor would come shortly, only they could tell.23
Like the rest of the Japanese connected with Operation Hawaii, the consulate fulfilled its duty to the cause. On December 1 Kita dispatched an extensive report on ship maneuvers, an example of excellent reporting, careful observation, and calculation as well as logical conclusion.24 This information would be of priceless value to the task force if it failed to discover Kimmel’s ships in either Pearl Harbor or Lahaina and hence had to activate one of Genda’s alternate plans to cover these eventualities.
Rochefort’s airwave detectives continued to zero in on Japan’s southward movements in spite of maddening difficulties. Code change or no, had Nagumo broken radio silence during this time there seems little doubt that Rochefort would have locked in on him. But Japan’s strict security paid off, as indicated by Rochefort’s summary for December 2:
Almost a complete blank of information on the Carriers today. Lack of identifications has somewhat promoted this lack of information. However, since over two hundred service calls have been partially identified since the change on the first of December and not one carrier call has been recovered, it is evident that carrier traffic is at a low ebb.25
Other intelligence organizations also had their own problems on this day. The FBI had been listening in on a suspect in its own office building. Some telephone company employees accidentally discovered the tap and reported it to their superiors. The District Intelligence Office contact at the company passed this on to his own unit; then someone in DIO tipped off the FBI that its tap had been uncovered.
Shivers descended upon the telephone company and read the riot act about this violation of confidence. When Mayfield learned about this, he was angry with the FBI for failing to consult with him, and he worried about the breach of security. Immediately his thoughts turned to his taps on the Japanese consulate telephones. He knew about the Navy Department’s instructions against rocking the international boat. If his surveillance at the consulate came to light, this could really blow up a storm.
Although few people in DIO knew it, the office had been covering five or six lines in the consulate, with an average traffic of fifty to sixty calls a day during 1941.26 This traffic had produced nothing of sensational importance, but it had given valuable insights into the personalities of consulate members and those who dealt with them. And December 2, 1941, was precisely the wrong moment to sacrifice intelligence upon the altar of international amity. But that is just what Mayfield did. “At 4 P.M. Honolulu time in the 1941st year of Our Lord, December 2nd inst. I bade my adieu to you my friend of 22 months standing. Darn if I won’t miss you!!
“Requiescat in Peace.” Thus Chief Ship’s Clerk Theodore Emmanuel signed off from his long watch.27
But it so happened that DIO had overlooked one telephone line—that to the cook’s quarters—and this one the FBI had been covering ever since they found the omission. Mayfield had been upset because Shivers had not confided in him; now he turned the tables and failed to advise the FBI that he had withdrawn the Navy’s taps. Had Shivers known, he would have acted promptly to replace the Navy’s coverage with his own.28 Here again we find a sad lack of coordination in a vital area when so much depended upon cooperation between U.S. agencies.
Kimmel’s primary problem on December 2 continued to be the proposed moving of Marine Corps aircraft to outlying islands and the contemplated transfer of these bases to Army jurisdiction. He met with Short to discuss the matter29 and wrote a long letter to Stark explaining it fully. Almost casually, in a postscript, he advised: “You will note that I have issued orders to the Pacific Fleet to depth bomb all submarine contacts in the Oahu operating area.” In another PS he expressed his fear that “we may become so much concerned with defensive roles that we may become unable to take the offensive. . . .”30 This characteristic missive proved the last in the extensive Stark-Kimmel correspondence of 1941 before the attack.
On December 2 the Foreign Ministry dispatched to Kita an important espionage message:
In view of the present situation, the presence in port of warships, airplane carriers, and cruisers is of utmost importance. Hereafter, to the utmost of your ability, let me know day by day. Wire me in each case whether or not there are any observation [possibly a garble for “obstruction”] balloons above Pearl Harbor or if there are any indications that they will be sent up. Also advice sic me whether or not the warships are provided with antimine nets.31
Here was another indication that Japanese interest centered on Kimmel’s ships “in port” as well as on their operational movements. This message contained more tip-offs than the simple phrase “in port.” Tokyo also wanted to know about barrage balloons and nets—protective measures against attack from above and below. These queries resulted from Genda’s and Fuchida’s proddings, for they had to be sure on these two points before sending their planes to Oahu. It would be difficult to find a clearer expression of intent. But, although intercepted at 0707 on December 2, this message was not mailed until December 11. It reached Washington on December 26 and was translated on the thirtieth.32
Kita received instructions from Togo on December 2 to burn all his codes except one each of Types O and L. He was also to burn all secret documents, taking precautions against “outside suspicion.” The Foreign Ministry added, “Since the foregoing measures are in preparation for and in consideration of an emergency, keep this matter to your Consulate alone, and we hope that you will hereafter carry out your duties with calmness and care.”33
Tokyo sent similar messages to all of Japan’s diplomatic officials in “North America (including Manila), Canada, Panama, Cuba, the South Seas (including Timor), Singora, Chienmai,” as well as to all officials in British and Dutch territory. The message to Washington also ordered Nomura: “Stop at once using one code machine unit and destroy it completely. . . . At the time and in the manner you deem most proper dispose of all files of messages coming or going and all other secret documents.”34
For the Honolulu consulate this meant that it would no longer use the high-grade J-19 system; it would have to rely upon the PA-K2. Thus, in the remaining days before the attack, information shuttled between Tokyo and Honolulu in a code which would prove much simpler for Rochefort and his men to break. And these dispatches would include some of the most revealing in the entire chain. Unfortunately for the Americans, DIO received the copies from RCA just too late to break before the attack.
Japan had a sleight-of-hand trick up its sleeve. This was the dispatch of the liner Tatuta Maru from Yokohama on December 2, ostensibly bound for San Francisco via Honolulu. The ship’s announced purpose was to evacuate from Japan such foreigners as desired to depart and to bring back Japanese from the United States. In essence, all would leave American soil except staff members of the diplomatic missions and a scattering of financial interests. From San Francisco the liner was supposed to call at the Mexican port of Manzanillo on December 19, at Balboa on December 27, thence proceed back home. The press in both Japan and the United States publicized the sailing extensively.35
The scheduled voyage was in reality a planned hoax. Tatuta Maru would reverse course for home after the first few days en route. Her captain did not know about the Pearl Harbor attack. He merely had instructions that on or about December 8 he would receive important orders and must act accordingly. Commander Toshikazu Ohmae of the Navy Ministry, who knew the entire story, feared that when the ship began to turn back, the American passengers might hijack it and force the captain at gunpoint to continue straight to the United States. So Ohmae asked the commanding officer of the Tokyo Communication Corps for twenty pistols “for a special mission.” He packed them in a box and took them to the skipper of the liner, with instructions to open the box at 0000 hours on December 8.36
In Tokyo Yamamoto awaited his summons to the palace to receive the imperial rescript wishing him success in the forthcoming conflict. In the northern Pacific on December 2 Nagumo rode herd on his armada, here pulling a ship back into the formation, there dispatching a destroyer on guard. He made a few changes in course and at 0722 ordered: “While the air raid force heads south with high speed . . . the submarine division will guard the rear of the main force following it with appropriate distance. After the main force reverses its course take the ordered position.”37
Ugaki had seldom been busier. He drafted a message for Yamamoto to send to the fleet before going to war and came up with: “The rise and fall of our Empire depends upon this war. Each of you will exert your best effort to accomplish your mission.” He showed this to Watanabe, asking him to consult with the other staff officers. Later Watanabe returned and suggested a minor change which Ugaki promised to consider. Obviously Ugaki felt a genuine concern that Yamamoto’s exhortation should find a worthy place in Japan’s naval annals. He remembered the famous signal which Togo had given his fleet at the Battle of Tsushima: “On this one battle rests the fate of our nation. Let every man do his utmost.”38 He decided:
The draft must be by no means inferior to this. Because, although any war decides the fate of a country, it seems to us who are confronting the present situation that the very war we are going to have will really decide the fate of our country. . . . Our posterity may not regard this as an unusual case, but I myself regard this war as tantamount to Japan’s going to war with the whole world.
At 1700 a telegram from Ito authorized the opening of Imperial General Staff Naval Order No. 12. “By this we are ordered to appeal to arms effective 0000 on 8 December and thereafter. The China Area Fleet and each Naval Station was ordered to appeal to arms after the receipt of word of the first attack by the Combined Fleet. Thank goodness!” With this pious reflection, at 0730 Ugaki dispatched to the Combined Fleet one of the briefest but most historical messages in the annals of naval warfare: “Niitaka yama nobore ichi-ni-rei-ya.” (“Climb Mount Niitaka, 1208.”)39 This signified that X-Day had been established at 0000 December 8 (Japan time). Nagumo’s task force received this information at 2000;40 at this hour the First Air Fleet was about 940 miles almost directly north of Midway, well beyond the arc of U.S. reconnaissance flights.
Although many Japanese naval officers believe the exact wording of this dispatch had no particular meaning, being a more or less random code selection, one cannot but note that Mount Niitaka in Formosa was the highest peak in the Japanese Empire. And “Climb Mount Niitaka” signified that Japan was about to scale the most formidable symbolic mountain in its history.