Pearl Harbor Betrayed (30 page)

Of one thing we may be certain: in later years, Kimmel understood thoroughly how decisive the breakthrough in torpedo delivery during 1941 had been. In an aide-mémoire dated 15 August 1945, he wrote: “The fact that the Japanese aerial torpedoes could be launched in less than 40′ of water and make successful runs was unquestionably a considerable factor in the Japanese decision to make the attack on the fleet at Pearl Harbor.”
33

*   *   *

On 7 November Admiral Yamamoto ordered all ships assigned to the Hawaiian Operation to depart their various anchorages on or about the fifteenth and to proceed as single vessels or in small formations to rendezvous in isolated Tankan (Hitokappu Wan) Bay, Etorofu Island, in the northern Kuriles, arriving no later than the twenty-second. On the same day, Yamamoto issued Combined Fleet Top Secret Operation Order No. 2, implementing Order No. 1 and establishing 8 December (7 December Hawaii time) as “Y” Day—the approximate date for the commencement of operations. An Imperial Naval Order issued by the Imperial General Headquarters on 2 December would confirm Yamamoto's No. 2 and declare 8 December to be “X” Day—the exact date on which the raid on Hawaii would be made: “The hostile actions against the United States of America shall commence on 8 December.”
34
The provisional date (“Y”) and the finally determined date (“X”) proved to be one and the same.

The fleet that assembled in Tankan Bay consisted of, for aerial attack: the Navy's six first-line carriers,
Akagi
(flagship) and
Kaga
(1st CV Division),
Soryu
and
Hiryu
(2nd CV Div.), and
Zuikaku
and
Shokaku
(5th CV Div.); for guard and support: battleships
Hiei
and
Kirishima
(3rd BB Div.) and heavy cruisers
Tone
and
Chikuma
(8th CA Div.); for guard and escort: light cruiser
Abukuma
and destroyers
Tanikaze, Urakaze, Isokaze, Hamakaze, Akigumo
(17th DD Div.),
Kasumi, Arare, Kagero,
and
Shiranuhi
(18th DD Div.); for patrol: submarines
I-19,
I-21,
and
I-23
(2nd SS Div.); for bombardment of Midway Island on return voyage: destroyers
Akebono
and
Ushio
(7th DD Div.); and for supply: tankers and auxiliaries
Kyokuto Maru, Kenyo Maru, Kokuyo Maru,
and
Shinkoku Maru
(1st Supply Train),
Toho Maru, Toei Maru,
and
Nihon Maru
(2nd Supply Train).

These were not the only naval vessels assigned to the Hawaii Operation, however. Already at sea was the Advance Expeditionary Force composed almost entirely of fleet submarines, twenty in number. Most were assigned to blockade of Oahu and strangulation of the entrance and sortie channel at Pearl. Two were assigned to reconnaissance of key points. And five were each to launch a deck-borne forty-five-ton midget submarine in the southern approaches to Pearl. Seventy-four feet in length, carrying two crewmen and armed with two torpedoes, the midgets' mission was to pass submerged beneath the torpedo net guarding the channel entrance and to launch torpedoes at capital ships from inside the harbor. Since the existence of the midgets that formed what was called the Special Attack Unit had successfully been kept secret, it was thought that the American defenses would miss their penetration. In one midget that was captured after beaching off Bellows Field, U.S. investigators would find silhouettes of Oahu from every angle of approach, exact silhouettes of all ships of the fleet, and charts of Pearl Harbor that were impressively accurate. Meanwhile, the larger boats outside the harbor would torpedo any American ships that tried to sortie during or after the air assault, and to the east, interdict any surface reinforcements dispatched from the West Coast.

The entire submarine force was under the command of Vice Admiral Shimizu Mitsumi, C-in-C of the Sixth Fleet, who accompanied the advance force to a point short of Oahu on board his flagship, the cruiser
Katori
. The submarines departed Kure and Yokosuka Naval Stations between 18 and 20 November for rendezvous and final refueling at Kwajalein in the Marshalls. (A few, delayed in leaving Japan, proceeded directly to Hawaii.) Yamamoto had permitted the participation of this more conventional naval force in the operation on the grounds that, according to the tactical war games projections, aircraft alone were not likely to destroy the American battle line. Fuchida, however, was said to be furious about their inclusion. First, the confident airman argued, they were not needed. Second, they presented the serious risk of compromising the air attack if one of their number was detected prematurely. He would be proven right on both counts.
35

*   *   *

While these movements of ships and boats were under way, the Japanese Foreign Ministry and military engaged in a number of calculated deceptions. On 7 November, the date when Y-Day was set, an unnamed Japanese, reportedly acting at the request of Foreign Minister Togo, visited Ambassador Grew and urged “repeatedly” that, irrespective of the merits of the Japanese diplomatic position, it was “of the highest importance that the Washington conversations be continued and not [be] permitted to break down.”
36
Equally insistent were Togo's messages later to his negotiators in Washington, Nomura and Kurusu. On 28 November, when the Striking Force was well out to sea on its passage to Hawaii, the foreign minister sent the following signal: “In two or three days the negotiations will be de facto ruptured. This is inevitable. However, I do not wish you to give the impression that the negotiations are broken off. Merely say to them [Secretary Hull and his aides] that you are awaiting instructions.” Four days later, Togo told them that “the date set [29 November] has come and gone and the situation continues to be increasingly critical. However, to prevent the United States from becoming unduly suspicious we have been advising the press [that] … the negotiations are continuing.”
37
These “deceit plan messages,” as they came to be called, were decrypted and read in Washington, though knowledge of their content was not shared with Kimmel or Short.

On the military side, sailors from the Yokosuka Naval Barracks were sent on liberty to Tokyo and Yokohama on highly visible sight-seeing tours to project an image of ordinary peacetime casualness. And the Pacific liner
Tatsuta Maru,
with a full passenger list, including Americans who wished to evacuate, was permitted to depart Yokohama for Honolulu and San Francisco on 2 December; though she reversed course on the eighth (Japan time) upon receipt of orders from the Navy Ministry. In accordance with the deception plan, the Striking Force proceeded to the Kuriles under strict radio silence. The Morse code sending key that was wired to the continuous wave radio transmitter on each ship was sealed or dismantled, and in some cases fuses were removed from the circuitry, to ensure that the attack fleet was dumb but not deaf, so as to preclude the possibility that an errant transmitted signal might give away the position of the carriers to American direction-finding (DF) receivers. Oscilloscopes attached to those receivers, furthermore, could distinguish the transmission patterns of the various ships, e.g., those of the
Akagi
from those of the
Kaga
. That imposition of radio silence, say
all
the Japanese who oversaw or participated in the raid and who wrote or spoke about it in later years, remained in force until the launch of aircraft on 7 December.
38
In the meantime, communications between ships were conducted by means of signal flag by day and blinker light by night.

*   *   *

When were the Japanese carrier pilots told of the objective for which they had been training? The question admits of several answers depending on the witness speaking. One carrier pilot told postwar interrogators that all officer pilots—but no petty officer or enlisted—were briefed on the operation aboard the
Akagi
in Shibushi Bay on 5 October. The briefers were Yamamoto and the chief of staff of the carrier fleet, Rear Admiral Kusaka Ryunosuke. The pilots were told, said this unnamed source, that the attack would be made on 8 December (Japan time). A second carrier pilot, identified as Shiga Yoshio, independently confirmed the particulars of the foregoing account, including the site and the roles of Yamamoto and Kusaka, but differed on the date, which he set at 5 November. According to Shiga, the pilots' reaction to the briefing was one of general pessimism: “All felt that it was a suicide mission.”
39
These two interrogation responses bear about them an air of unreality. First, it is not credible that pilots would be briefed by the C-in-C Combined Fleet. Second, Yamamoto had not even by the latter date issued his Order No. 1 establishing 8 December as Y-Day.

Far more likely is the date of 23 November given by historian Gordon W. Prange, based on extended interviews he conducted with Kusaka, Genda, and Fuchida. On that date, which was one day after the Striking Force had assembled in its jump-off point, Tanken (Hitokappu Wan) Bay, and on board the flagship, carrier
Akagi
(Red Castle), force commander Vice Admiral Nagumo Chiuchi went over their destination and targets with the captains and staffs of the carriers, battleships, cruisers, and destroyers, as well as with the three submarine skippers and the commanding officer of the tanker fleet. He explained that if during their passage to Hawaii there should be an agreement struck in the Washington negotiations the Striking Force would be ordered to return to home bases without executing. Similarly, he told his commanders and staffs, should the force be detected by the enemy prior to or on X-Day minus two, the force would reverse course. If discovered on X-Day minus one, however, he, Nagumo, would make a decision whether to continue the advance, based upon the circumstances. If an enemy force confronted them on X-Day,
Kido Butai
would fight it out with them at sea, calling up the remaining vessels in the Inland Sea for reinforcement.
40

Nagumo seems to have been of two minds on the question of how many attacks should the Striking Force make on Pearl Harbor and the Oahu airfields. On the one hand, he told his commanders that their single two-wave morning attack, as planned, should be sufficient to cripple, if not altogether destroy, the U.S. Pacific Fleet. On the other hand, he issued under the same date Operation Order No. 3 that stipulated (as Genda and Fuchida had been pressing) that “if the land-based air power has been completely knocked out, repeated attacks will be made immediately in order to achieve maximum results.”
41

On the same day, after lunch, Nagumo told the assembled officer pilots for the first time that they were going east to attack Pearl Harbor. On hearing the news, according to Fuchida, quite aside from pessimism, “their joy was beyond description.”
42
Genda and Fuchida then provided the young airmen a day-and-a-half-long (23–24 November) detailed briefing on the attack. There would be two waves of aircraft, they informed them, the first to launch when 230 nautical miles north of Oahu, timed to arrive over Pearl Harbor and surrounding airfields at about 8:00
A.M
. Hawaii time; the second to launch from 200 miles out, timed to arrive over targets at about 0900. Fuchida himself would lead the first wave, consisting of fighter aircraft (Mitsubishi A6M2 Type 21 Reisen Zero), torpedo bombers (Nakajima B5N2 Type 97 Kate), high-level (horizontal) bombers (the same Type 97, each fitted with one 1,760-pound armor-piercing gravity bomb), and dive-bombers (Aichi D3A1 Type 99 Val). Lt. Comdr. Murata Shigeharu would lead the centrally important torpedo flight.

The second wave, consisting of all types except torpedo bombers—they were expected to be too vulnerable to AA fire after their surprise use in the first wave—would be commanded by Lt. Comdr. Shigekazu Shimazaki. The two waves would be preceded by a flight of two Aichi E13A1 “Jake” reconnaissance floatplanes with three-man crews catapulted from the heavy cruisers
Tone
and
Chikuma
. Their purpose was to determine what ships of the U.S. fleet were at Pearl Harbor and which (if any) were at Lahaina Roads on the neighboring island of Maui. The scouting period over targets was set to last one hour, but when Murata and other pilots objected that the planes' necessary breaking of radio silence and their subjection to sighting might jeopardize the critical element of surprise, it was agreed by Genda, Fuchida, and, later Nagumo, to halve the time to thirty minutes.

Genda went over the sequence and spacing of takeoffs from the six carriers, the process of forming up aloft, the courses to be flown, rendezvous points, changes in altitude to be executed, and the exact approach routes to targets. He emphasized that the essential ingredients of success were teamwork, surprise, timing, and simultaneity of attacks. For example Murata's flight of forty torpedo bombers would divide into two groups and strike the battleships and cruisers moored to the southeast and northwest of Ford Island from two different directions at the same time. Fuchida explained the various signals that he would use during the first wave's approach to targets. Upon reaching the northern tip of Oahu, he would fire one flare if it appeared that the aircraft had caught the enemy with his guard down, in which case one particular sequence of attacks would take place; he would fire two flares if it appeared that the enemy had been alerted, in which case another, different, sequence would be followed. And if, when Pearl Harbor came into view, Fuchida was convinced that surprise had indeed been achieved, he would break radio silence and signal the carriers:
“Tora! Tora! Tora!”
(“Tiger! Tiger! Tiger!”)

In daylong breakout sessions with twenty-six separate groups of pilots, Fuchida went over the operation in exacting detail. Using models of Pearl Harbor, and Oahu, with miniature mock-ups of ships and ground installations, as well as maps and diagrams, he pinpointed each group's targets and approach routes, and drilled the officers (and their enlisted personnel) on their responsibilities until they had them thoroughly memorized.