Almost a decade ago the United States suffered one of the greatest military defeats in its history. In the space of one hour and fifty minutes all eight of the battleships comprising the backbone of the Pacific Fleet were sunk or heavily damaged; three light cruisers, three destroyers and four miscellaneous vessels were disabled; 188 Military planes were destroyed, and the lives of 2,396 American citizens lost. In less than two hours the United States was stripped of any claim to naval supremacy in even the eastern waters of the Pacific Ocean, and Japanese prospects of creating a Greater East Asia Empire protected by an impregnable ring of island bastions were enormously strengthened. Pearl Harbor promptly took its place in the language alongside Hastings and Waterloo as a synonym for disastrous defeat, and December 7, 1941 became, in the late President Roosevelt’s words, “a day that will live in infamy.”
Historians of some future time interested in the events of this day are not apt to complain of any lack of relevant documentation. Indeed, anyone even slightly familiar with the exhibits and transcripts of testimony bearing exhaustively upon almost every aspect of the background of this calamitous defeat cannot help but feel sorry for the sad lot of such hypothetical historians wallowing haplessly in the endless verbiage of no less than eight administrative and congressional investigations.
Strangely enough, however, even the marathon investigation conducted in 194546 by the Joint Committee on the Investigation of the Pearl Harbor Attack failed to develop in any detail an aspect of the affair possessed of the highest historical and military importance. Throughout these hearings emphasis was placed on the assessment of responsibility among our high military and political authorities for their failure to take reasonable precautions which would have resulted either in forestalling the actual attack or in minimizing its element of surprise. Under these conditions it was perhaps not to be expected that much attention would be devoted to the development of a detailed picture of the attack from the Japanese standpoint. But, as a result of this and the similar focus of other investigations, it happens that today even the well-informed American has a very partial knowledge of the circumstances of the Pearl Harbor attack. He knows it only from the American side, that is from the angle of the bitter recipient of a blow generally regarded in this country as the last word in the annals of international treachery and double-dealing.
There remains, however, another way of looking at this episode, namely, from the Japanese viewpoint. After all, they planned and carried out what we must ruefully admit is one of the greatest single naval victories of this century. This called for exceptional talent on their part, for brilliant planning, great courage, and daring execution. The ethics of the assault are quite another matter, but, from a technical standpoint, the Pearl Harbor attack was a remarkable feat. History and the ominous potentialities of our current international situation combine to demand that we consider this broader view of the matter and learn something of the background and launching of the attack from the Japanese as well as the American standpoint. The story is a grimly fascinating one and the moral is as applicable to the future as to the past.
Recently there has become available in this country the materials from which it has been possible to reconstruct the following account. They emerged from the proceedings and exhibits of the recently-concluded Tokyo War Crimes Trial, technically known as the International Military Tribunal for Far East. One count in the indictment of the 28 Japanese accused of conspiring to bring about the launching of an aggressive war and of numerous other major crimes against the peace concerned the naval preparations for this war. In the course of hearings before the International Court on this score, there appeared to testify for either prosecution or defense a great many of the Japanese officials and naval officers who had planned and actively directed the Pearl Harbor attack. Among them were, for example, Shimada Shigetaro,1 then Minister of the Navy; Nagano Osami, then Chief of the Japanese Naval General Staff; Kusaka Ryunosuke, Chief of Staff of the First Air Fleet, which carried out the Pearl Harbor attack; Fuchida Mitsuo, who personally commanded the first wave of attacking planes, and numerous others of equal importance. Among the major documents adduced in evidence were Combined Fleet Top Secret Operation Orders Nos. 1, 2, 3, and 7 which, among them, set forth the over-all plan and strategy of the naval war in the Pacific and actually launched the Pearl Harbor Task Force on its deadly mission. From this testimony and these exhibits there emerges the following story.
I
Planning the Pearl Harbor Attack
The idea of a carrier-based air attack on the United States Fleet at Pearl Harbor was originated and officially sponsored by the late Admiral Yamamoto Isoroku, who in 1941 held the office of Commander-in-Chief of the Combined Fleet, the highest operational command in the Japanese Navy. All of his surviving colleagues agree on that point. Surprisingly enough, such a plan did not gain final acceptance as a part of the over-all Japanese strategic concept until late September, or early October, 1941, a bare two months before the launching of the actual blow.
Admiral Yamamoto is thought by his friends and associates to have conceived the Pearl Harbor plan early in January, 1941. The first reliable record of its existence occurs early the following month when Captain Genda Minoru, a staff officer of the Eleventh Air Fleet, was summoned to Kanoya by his friend and superior, Rear Admiral Onishi, Chief of Staff of the Eleventh Air Fleet. There he was shown in strict confidence a private letter which Onishi had received from Yamamoto. This set forth the Commander-in-Chief’s conviction that, in the event of a war with the United States, there was small prospect of Japanese victory unless at the very outset of hostilities a crushing blow could be delivered at the United States Fleet in Hawaii. Such an attack, Yamamoto said, could be launched by the First and Second Air Squadrons based on a carrier task force which he would personally command. The letter concluded with a request that Onishi carry out a secret study of the feasibility of such a plan.
Captain Genda was ordered to make this study and devoted about ten days to drawing up a staff report for his chief. He concluded as a result of his investigations that Yamamoto’s plan, while risky and extremely difficult from a technical standpoint, was not impossible of accomplishment. Admiral Onishi forwarded this report together with his own observations to Yamamoto about the middle of February, 1941.
Thereafter the plan germinated on the higher staff levels of the Combined Fleet Headquarters for several months without notable development. At the time of the organization of the First Air Fleet in April, 1941, for example, it was still the most carefully guarded of secrets. Although this fleet was intended to carry out the actual strike and was, therefore, most intimately associated with its planning, only four of its topranking staff were aware of the existence of the plan. It was not until May, as a matter of fact, that the Japanese Naval General Staff itself was taken into Admiral Yamamoto’s confidence. This is the more surprising since officially it was the Naval General Staff, under the command of Admiral Nagano Osami, which was responsible for the development of major naval strategy. Yamamoto, as Commander-in-Chief of the Combined Fleet, was directly subordinate to Admiral Nagano and was required to clear all important policy decisions with him before taking any action thereon. The final approval or rejection of the Pearl Harbor plan lay, therefore, with the Naval General Staff and primarily with Nagano, not with the Combined Fleet. Prior to May, 1941, then, the Pearl Harbor plan had no formal status as even a project for inclusion in the official naval strategic concept but remained the pet and more or less private theory of Admiral Yamamoto and a very limited coterie of his staff in the headquarters of the Combined Fleet and the First Air Fleet. With its submission to the Naval General Staff, however, this status immediately changed.
The plan presented to the Naval General Staff in May, 1941, was not, properly speaking, a plan at all. Few, if any, of the operational or logistic details, which constitute the heart of a naval plan, were included. It seems to have been a bare statement of a theory of operations to be tested and possibly put into effect in the event of a war with the United States. As such it was postulated on two basic assumptions:
- that a major portion of the United States Fleet would be at Pearl Harbor, if such a war broke out; and
- that Japan could deal a crushing blow to this Fleet by a carrier-based air attack.
The submission of this plan, with all the weight of Admiral Yamamoto’s official and personal influence behind it, at once precipitated a long and bitter controversy within the ranks of the higher Japanese naval authorities. The principal source of disagreement was the fact that such an attack on Pearl Harbor was completely opposed to a well-established master plan of Japanese naval strategy, although there were also serious strategic and technical objections to the plan in its own right. To understand this controversy it is necessary to know something about Japanese naval doctrine in 1941.
For some time prior to the outbreak of general warfare in the Pacific, Japanese naval and military planning had been directed primarily at the occupation or control of a number of rich and strategically situated lands in Eastern and Southeastern Asia. These plans were formulated as a part of the broader and more basic politico-economic concept of a Greater East Asia Co-Prosperity Sphere under Japanese direction and leadership. Although the men in command never lost sight of the Soviet menace to their north and, in a long-term sense, cherished the hope of some day taking over the Siberian lands east of Lake Baikal, their immediate concern and focus was upon expansion to the west and south. There was far more uniformity of opinion on this policy among the Japanese leadership than is generally recognized, and this substantial agreement dates back at least to July, 1940. As a result of this, Japan’s primary national objectives in 1941 were to end the China Incident, consolidate her politico-economic control of the China-Manchukuo Area and integrate it with the Japanese economy as the heartland of Greater East Asia. Simultaneously and beyond this, she equally hoped to gain effective control of French Indo-China and the Netherlands East Indies in the immediate future and of the remaining southern regions east of the Indian frontier not too long thereafter. It was generally hoped, and for quite a while believed, that it would be possible to accomplish these ends by diplomatic means aided by judiciously timed military pressure. The inevitability of war with the United States and Great Britain was accepted slowly and often with great reluctance. Certain important political elements were never convinced of its wisdom or necessity.
It was against this background that general naval strategy had been formulated. It was, of course, based on the hypothesis that diplomatic means would not prove adequate and that Japan would be forced to fight for the accomplishment of her basic national objectives. In such a war, given the context of international affairs in 1940-41, it was quite apparent that Great Britain, France, and Holland would be unable to offer any prolonged resistance in the Far East. They were on the very brink of what appeared to be final defeat in the war in Europe. The only real threat to Japanese ambitions came from the United States, and, in Japan’s eyes, active American intervention in the Far Eastern situation was daily becoming more probable. The essential problem then, as it presented itself to Japan’s naval planners, was how to take over the Southern Regions (basically, how best to assist the army in so doing) and at the same time to take effective precautions against American naval intervention.
The generally accepted answer in high Japanese naval circles in 1941 was simple and well conceived. Specifically, it reduced to these points:
- provision of the shipping and escort vessels necessary to transport a sufficient number of troops to the countries of Southeast Asia and to carry out the naval aspects of the assault, thus realizing the basic objectives of the Greater East Asia plan and at the same time acquiring for themselves an adequate supply of desperately needed oil from the Netherlands East Indies; and
- seizure and fortification of the island ring commanding the approaches to Eastern Asia.
This second aspect of the plan envisaged Japanese control of all the South Pacific islands as far south as New Guinea and as far east as the Solomons. There is no reliable evidence of an official intention to occupy either Australia or New Zealand at this stage. For the time being at least, they intended simply to isolate the two dominions. To these southern islands they planned to join the Japanese Mandated Islands and thus, after capturing the Philippines and Guam, to create what they hoped would be an impregnable island bastion effectively barring forever the approach of an American fleet to the shores of Eastern Asia and thus safeguarding their vital coastal axis of communications.
The Japanese Naval General Staff felt that the execution of the southern features of this plan alone would take the major part of their available forces, especially since the British and Dutch were known to be devoting every energy to strengthening the defenses of Malaya and the Netherlands East Indies. They had reluctantly concluded, therefore, that the Southern Operation should have first priority, and that what forces remained would have to be devoted to the Philippines-Guam operations, to taking over the South Pacific islands, and to manning the defenses in the Mandated Islands. In the event that the United States launched a major naval assault on any part of this island ring during the early stages of the war, it was anticipated that the heavier units of the forces sent to Southeast Asia could be diverted to strengthen the fleet locally available.
It will readily be appreciated that the emphasis and inspiration of this accepted strategic concept was completely opposed to that of the bold and risky Pearl Harbor plan formally advanced by Admiral Yamamoto in May, 1941. The ensuing controversy was prolonged and bitter.
In general, the Naval General Staff under the command of Admiral Nagano steadfastly opposed the Pearl Harbor plan in its earlier stages. As the institutional author of the accepted island-ring defense plan, this bias against competing concepts was only to be expected, but they also advanced an impressive list of more relevant objections. They claimed that, given the demands of the Southern Area campaigns, Japan’s naval air strength was not adequate to provide carriers, planes, and personnel for both operations and that, even if they could, the Pearl Harbor plan was simply too risky. It entailed the commitment on a single strike of all of Japan’s first-line aircraft carriers, amounting to three-fifths of her total strength in this class. If anything went awry, their loss would be disastrous. Furthermore, they complained that it was exceedingly difficult to obtain reliable advance intelligence about the disposition of American naval forces in the Hawaii area and that the entire plan depended upon the presence of the major elements of the Pacific Fleet in Pearl Harbor on D-day. At best this was a dangerous gamble. The Fleet might well be at sea, in which case the strike would prove an utter and costly fiasco. Again, the success of the venture was completely dependent on the element of surprise, and it was believed that it would be very difficult to mount so large-scale an attack and still preserve the necessary secrecy. The route to Hawaii from Japan was a long one, roughly 2,880 nautical miles by the path actually followed, and the possibility of premature discovery was consequently considerable.
These were cogent and weighty objections, the more so because they were reinforced by the political and diplomatic views then held by the dominant section of the Japanese naval leadership. High naval opinion in general during the spring and early summer of 1941 was decidedly less aggressive than that of their army colleagues. The Navy still tended to believe that the China Incident should be settled before embarking on further overseas adventures and that national ambitions in Southeast Asia might yet be achieved by peaceable diplomatic means. A war with the United States did not appear to these admirals as either necessary or desirable. This attitude was gradually to change after the outbreak of Russo-German
hostilities in June, the United States’ freezing of Japanese assets in July, and the further deterioration of Japanese-American relations which followed these events, but in May, 1941, the naval leadership was still not reconciled to the inevitability of war with the United States. They were not, therefore, as interested in Yamamoto’s theory as they might otherwise have been, and for the time being no decision was taken on the Pearl Harbor plan.
By late August or early September, however, high Japanese opinion in general, including naval opinion, had undergone considerable change. The outbreak of the Russo-German War in June had given them a degree of security along their northern frontier far beyond that “guaranteed” by the Russo-Japanese Non-Aggression Pact of April, 1941. The temptation to capitalize on this newly acquired freedom of action by a bold threat to the south was enormous. The constantly deteriorating course of Japanese relations with the United States, Great Britain, and Holland was, furthermore, making it increasingly apparent that Greater East Asia was not to be won by diplomatic representations and demarches alone. Gradually the conviction was hardening that this was the time of the century for bold and decisive action, that the risks of war should be faced, and that the prize was worth the risk.
Consequently, the months of- August and September, 1941 were a period of great activity in several Japanese naval headquarters. The Naval General Staff refurbished the classic island-ring defense plan. At the same time orders, presumably from Headquarters Combined Fleet, were issued to the staff of the First Air Fleet to draw up an operations plan for an attack on the United States Fleet at Pearl Harbor. The same Captain Genda who had made the original study of the feasibility of this plan for Admiral Yamamoto served as secretary to the staff group which carried out this order. In his testimony given at the Tokyo trial of major war criminals, he described the resultant plan as similar in most important respects to that later used in the actual attack. It differed only in the rendezvous point prescribed for the task force in Japan and in the lack of any provision for a separate submarine strike to be coordinated with the air attack. This completed plan was then immediately presented to the Naval General Staff by Admiral Yamamoto with a strong plea that it be adopted.
It was, of course, impossible to ignore a request supported so strongly by the nation’s second ranking naval commander. The Naval General Staff, therefore, agreed to include the Pearl Harbor plan produced by the staff of the First Air Fleet (or possibly a slightly modified version thereof) on the agenda of a series of top secret “table-top maneuvers” to be held in Tokyo during early September. It was understood that if the plan stood up under the rigid tests applied during these war games and still promised a fair prospect of success, it would be given further serious consideration as a possible addition to the basic strategy to be followed in the event of a war with the United States.
The games were held at the Naval War College at Tokyo from September 2 to 13, 1941. They were attended by about forty of the highest ranking commanders and staff officers of the Combined Fleet and the Naval General Staff. Two general problems were under consideration. The participants were expected:
- to work out a detailed schedule for the naval aspects of the occupation of the Philippine Islands, Malaya, the Netherlands East Indies, Burma, and the South Pacific islands; and
- to test the feasibility of a carrier-based air attack on the United States Fleet in Pearl Harbor.
We need consider only the latter.
For this maneuver the participating officers were divided into N (Japanese) and A (United States) Teams. The N Team then received from the umpires an outline of the hypothetical conditions in accordance with which they were to plan their surprise attack on Pearl Harbor. According to the Chief Yeoman attached to this team—who later became an American prisoner-of-war—the conditions stipulated bore a very close resemblance to the terms later set forth in Top Secret Operational Order No. 1, which launched the Japanese attacks in the Pacific. From discussions among members of the N Team, this same Chief Yeoman gathered that they hoped to catch all major units of the Pacific Fleet in Pearl Harbor and that they expected to lose about one-third of the attacking force, including two aircraft carriers, in the course of the onslaught. It is also interesting to note that there was considerable debate within the N Team as to the feasibility of following up the initial air attack by a landing in force and a permanent occupation of the Hawaiian Islands. Admiral Ito Seiichi, Chief of Staff of the Combined Fleet, strongly favored such an endeavor while Yamamoto himself appeared to be in general accord, but the Deputy Chief of Staff, Captain Kurojima Kameto, was able to convince them of the insuperable logistical difficulties involved. It would have involved the use of an enormous transport and supply fleet which would have greatly slowed down the tempo of the entire operation and increased the possibility of premature detection. In any event, Japan simply did not have the trained personnel and ships to spare from the Southern Operations. Consequently, this scheme was reluctantly laid aside, though some hope of occupying Hawaii later in the course of the war lingered on. The N Team then proceeded to plan and carry out on a huge game board a hypothetical attack on the American Fleet at Pearl Harbor. Numerous serious technical difficulties were pointed up by this experience, but none of these were considered insoluble, and, as a result, the general verdict on the plan appears to have been that it was possible but risky.
The favorable outcome of the maneuvers did not, however, mean the automatic acceptance of the Pearl Harbor plan. The results of the games and the problems revealed thereby continued to be discussed and argued on higher staff levels throughout the rest of September. The weight of opinion in the Naval General Staff and Headquarters of the First Air Fleet—-the unit which would have to carry out the attack, if it was decided upon—continued to oppose the plan and to favor reliance on the classic strategy of an island-ring defense to protect the continent and the Southern Operations.
Against this stand Admiral Yamamoto advanced the following arguments. He claimed that as long as the United States had a powerful fleet in being there was a constant danger that they would be able to mount a successful attack on one or more of the outer islands, and, once having established a base thereon, that by island hopping they could gradually work through the island ring and cut Japan’s all-important lines of sea communication with Southeastern Asia. Therefore, the safest course of action for Japan was first so to reduce and cripple American naval strength that an attack on the island ring would be impossible. Japan could then consolidate her gains in the south and elsewhere at her leisure and, vastly strengthened thereby, could present an impregnable front to the United States.
This line of argument was probably bolstered by the fact that the existing Japanese military installations in the Mandated Islands appear not to have been particularly formidable or even extensive. It is quite true that the Japanese had fortified the islands in defiance of their treaty obligation not to do so. But it is erroneous to conceive of them in 1941 as an effectively fortified area. Many of the earlier installations generally regarded as military were not solely and specifically such at all. They are more accurately termed dual-purpose. They were capable of serving either civilian or military needs. Many airfields, harbor improvements, storage facilities, housing and office developments fell into this category. In general, the construction of actual military facilities took place at an astonishingly late date. The Aslito Air Base may have been begun as a specifically naval project as early as 1932, but it was dropped and really never completed. Again an alleged naval air base was started on Saipan in 1935. But in most instances the Japanese do not appear to have constructed gun emplacements, mounted guns therein, or taken the other final steps which are associated with military fortifications until the period 1939-40. Even then their preparations were somewhat desultory and circumscribed, possibly due to budgetary and technical limitations. The upshot was, however, that the defensive capacity of the vaunted island-ring was far from being what the Naval General Staff would have liked. In this sense the classic strategy espoused by this group was vulnerable to the extent that it rested upon the assumed invulnerability of a defense based on these islands. Yamamoto’s arguments in favor of the alternative Pearl Harbor plan were undoubtedly strengthened by this fact.
The final touch was added to these arguments by Yamamoto’s threat to resign, a contingency which the naval authorities were apparently most anxious to avoid. Yamamoto Isoroku was an exceptionally gifted naval commander in whose ability and integrity the high command had great faith, despite their disagreement over basic strategy. With a major war becoming increasingly probable by the day, they had no desire to have to select and orient a new commander-in-chief. Furthermore, in the existing context of Japanese domestic affairs, the resignation of so crucial an officer was quite apt to have serious political repercussions.
Under the combined pressure of these arguments and threats, opposition to the Pearl Harbor plan began gradually to dissolve towards the end of September. The staff of the First Air Fleet changed its mind first. During the early days of October, its commander, Vice-Admiral Nagumo Chuichi, announced to his staff and higher personnel that since, in the event of a war with the United States, they would probably have to attack Hawaii, their study and training programs should henceforth be designed so as to emphasize the problems of such a strike. Shortly after this, the Naval General Staff also withdrew its opposition and agreed to intensive and final studies of the plan. As these studies progressed the atmosphere underwent a complete change. Quite suddenly, during October, 1941, the Pearl Harbor plan was formally accepted by all higher naval authorities concerned and became the Navy’s most urgent activity.
At this point the drafting of the detailed orders and schedules necessary to launch the Pearl Harbor attack got under way. The basic order involved was the document known as Combined Fleet Top Secret Operation Order No. 1. This set forth the major strategy, general operational dispositions, communications plans, and supply arrangements for all naval operations to be undertaken by Japan during the opening stages of hostilities. It thus covered the Philippines, Guam, Malayan, South Seas, and other attacks as well as the Pearl Harbor strike. It is a large and detailed document of 151 pages, a copy of which our naval intelligence managed to salvage under dramatic circumstances from the hull of the Japanese heavy cruiser Nachi sunk in Manila Bay. This order was drafted during October, in part at least aboard Admiral Yamamoto’s flagship, the Nagalo, then anchored in Saeki Bay on the eastern coast of Kyushu. Final printing of this order began on November 1, 1941, more than a month before the actual strike, and took about three days. 700 copies in all were run off. The order was dated November 5, 1941,2 and was issued to authorized staff officers from other units of the fleet on that date in pursuance of a command given Admiral Yamamoto by the Chief of the Naval General Staff, Admiral Nagano Osami, on the same day.
Combined Fleet Top Secret Operation Order No. 1 prescribed only the general outline of naval strategy during the first phase of hostilities. It was necessary, therefore, that it be supplemented by a large number of secondary orders setting forth in detail the multitudinous provisions necessary for the execution of each individual attack. Such an order, known as Task Force Top Secret Operation Order No. 1, was drafted by the staff of the First Air Fleet (which was’ the unit designated as the Pearl Harbor Task Force) towards the end of October, 1941, and was submitted to Headquarters Combined Fleet for review and approval. To the writer’s knowledge, no copy of this document has yet been discovered. However, we know a good deal about its contents from reliable secondary sources and from the actual conduct of the attack. It was speedily accepted by Headquarters Combined Fleet, returned to the Task Force, and there printed, probably during the second week of November. It is known that a limited number of printed copies were distributed on November 17 before the Task Force left Saeki Bay for its northern rendezvous.
The general nature of this order is apparent from the description of the actual strike given below. Only one aspect requires special notice at this time. The order definitely included provision for the postponement or recall of the Pearl Harbor attack at any time up to the moment the planes actually released their bombs over the target. If, for example, Japan’s diplomatic negotiations with the United States had reached a successful conclusion after the Task Force had put to sea, the order stipulated that, upon proper notification, the fleet would return to a specified rendezvous point at 42° north latitude by 170° east longitude and remain there in a state of readiness until further instructions were received. The possibility that he might miss such an order through some failure of the communications system was later to cause the Task Force’s Chief of Staff great concern during their outward passage.
Two further orders merit notice. Combined Fleet Top Secret Operation Order No. 2, issued by Yamamoto on November 7, 1941, set “Y-Day” as December 8, 1941. “Y-Day” is defined in Combined Fleet Top Secret Operation Order No. 1 as a tentative and approximate date for the commencement of hostilities. This was later to be supplemented by another order specifying “X- Day,” the final and definite date for the actual launching of the attack. This second order, the number of which is not known, was issued by Headquarters Combined Fleet on December 2, 1941. It confirmed the tentative date contained in the “Y-Day” order and specified that “X-Day” should be December 8, 1941 (December 7, United States time).
December 8 had been accepted as a propitious date in discussions held in the Naval Section of Japanese Imperial Headquarters prior to November 7, 1941. It had been noted that, from the standpoint of a dawn attack on Pearl Harbor, December 10 would have been even better since the dark of the moon fell on that night. But December 10 (Japanese time) was a Tuesday in Hawaii and it was feared that the United States Fleet would be at sea. Counting, therefore, on the known custom of the Fleet during maneuvers to enter Pearl Harbor on Fridays and to leave on the following Monday, the Japanese naval command chose Sunday, December 8 as the date for launching the “Greater East Asia War.”
One final aspect of ‘the planning of the Pearl Harbor attack requires notice. That is the extreme secrecy maintained by the Japanese Navy up to the actual outbreak of war. Within high naval circles it was, of course, impossible to conceal the plan after the “table-top maneuvers” at the Naval War College in early September 1941, although relatively few appear to have been aware of its existence prior to that time. Outside of the Navy, however, the utmost secrecy prevailed. The prewar system of Japanese government was such that no outside sanction was necessary for the adoption of the Pearl Harbor plan. Technically this was a command decision, a matter of purely naval strategy, despite its world-shaking implications. Once the cabinet and Imperial Conference had decided in favor of war, the Pearl Harbor attack automatically followed as a consequence of the October decision of the Naval General Staff to include it in their basic strategy. Consequently, the Navy had been under no obligation to take anyone else into its confidence. There appears to be a fairly good possibility that even Tojo, then serving as both Premier and Minister of the Army, learned of the existence of the Pearl Harbor plan for the first time at a liaison conference held on November 30, 1941. Tojo himself explicitly stated this to be the case, and, considering the forthright quality of his testimony in general, there appears to be no overruling reason for doubting his claim. It is quite plausible in view of prewar Japanese practice. Tojo, in his capacity as Minister of the Army, had previously been informed of the nature of naval plans for the attacks on the Philippines and Malaya, but these were joint army-navy operations. Pearl Harbor was a purely naval strike, and seems, therefore, to have been mentioned to no one outside the Navy prior to the above-mentioned liaison conference of November 30, 1941. It is probable that at this time Togo, Minister of Foreign Affairs, and Suzuki, President of the Cabinet Planning Board, were also informed, but it is still doubtful that the other cabinet ministers knew of the plan. The Pearl Harbor attack was then as much of a surprise to the Japanese in general as it was to us.
II
Training and Preparations
In preparing the Pearl Harbor attack the Japanese naval planners had encountered several very difficult technical problems. Two of these were basic. The strike could not have been mounted had they not been solved. Two others, while serious and vexing, were not quite as critical.
The most difficult problem of all concerned the use of aerial torpedoes. It was generally agreed that these were the most effective of all possible aerial weapons for an assault on heavily armored warships. It was considered essential to the success of the attack that they be used. The difficulty lay in the fact that the waters of Pearl Harbor had an average depth of only forty-odd feet and no known type of aerial torpedo would function in such shallow waters. They would, upon launching, simply dive to the bottom of the harbor and there explode harmlessly. It was essential, therefore, that a shallow-diving torpedo be invented if the Pearl Harbor attack was to be carried out.
Japanese naval research institutes and technicians had been studying this and related torpedo problems since 1939, although not with the Pearl Harbor attack specifically in view. It was not until September or October of 1941, however, that they managed to perfect a stabilizing device which, when attached to their best models of aerial torpedoes, rendered them operable in such shallow waters. At this late date technicians attached to the First Air Fleet, working in cooperation with the Yokosuka Naval Air Corps and the Naval Air Technical Department, solved the problem, and then worked frantically to furnish an adequate supply of the new-model torpedoes to the planes of the Task Force. They completed this task only on the very eve of the Fleet’s departure from southern Japan for the rendezvous in the Kuriles. As a matter of fact, the aircraft carrier Kaga had to delay her departure for several days before her quota was ready.
The second crucial problem encountered was the fact that the ships participating in the strike must all have extraordinarily long cruising ranges. It is roughly 2,880 nautical miles from Hitokappu Bay in the Kuriles to Hawaii by the northern course planned and about 3,625 nautical miles back to the Fleet’s Inland Sea base. Refueling at sea would probably be possible on the outward voyage, weather permitting, but thereafter the ships would be in an operational status and on their own as far as fuel supplies were concerned. Of the six aircraft carriers involved, three—the Akagi, Soryu, and Hiryu—lacked adequate cruising range, as did all of the destroyers in the screen.
The solution reached was to postpone the final refueling on the outward voyage to the last possible moment, and to supplement their normal fuel supplies by as many additional drums as each ship could possibly carry. In the case of the carriers, in addition to an enormous deck load, it was decided to store extra fuel in their double bottoms. This decision precipitated one of those ludicrous administrative squabbles that so frequently beset great plans. There was a naval regulation forbidding the use of double bottoms for storage purposes. And, inevitably, no one was willing to assume responsibility for granting a dispensation from this regulation to the Pearl Harbor Task Force. As a consequence, it seems that in the last days before departure the much-harried Chief of Staff of the First Air Fleet, Vice-Admiral Kusaka, spent many valuable hours scurrying from bureaucrat to bureaucrat vainly seeking an exemption. It finally became necessary for the Commander-in-Chief personally to assume responsibility for any mishaps which might occur as a result of overloading before this obstacle was surmounted.
Several less serious problems also vexed the naval planners. They regarded the torpedo-plane assault as their heaviest offensive weapon, but they also realized that it would be necessary to supplement this by dive-bombing and horizontal-bombing attacks. There were a number of convincing reasons for this. It was well-known, for example, that the United States Navy frequently moored its battleships two abreast in their Pearl Harbor berths. In such a case only the off-shore vessel could be reached by aerial torpedoes. Again, they were not certain that the heavier ships would not be protected by anti-torpedo nets, though they had been advised by the Japanese consul-general at Honolulu as late as December 6 that he did not think there were any such nets. Finally, there was considerable doubt in higher naval circles as to the ability and skill of the pilots of the torpedo planes. Consequently, plans were made for both dive-bombing and high- level bombing attacks as well.
It developed also that there was a shortage of heavy aerial bombs for the high-level bombers, as a result of which it was found necessary to convert a large quantity of 800 kilogram (1,760 lbs.) sixteen-inch armor piercing shells for use as aerial bombs. This operation in turn involved considerable alteration of the bomb bays and dropping gear of the planes scheduled to use such missiles, as a consequence of which work parties were kept busy making last minute changes up to the very arrival of the Fleet at its rendezvous in the Kuriles.
The personnel situation raised further difficulties. All six carriers assigned to the Task Force were seriously under their wartime complement of flight personnel. Actually the navy as a whole had a critical shortage in this branch, which made it very hard to fill gaps in the Task Force. Yamamoto was adamant, however, in demanding the transfer of all flight crews from the two carriers of the Fourth Squadron—which were too small and slow to participate in the attack—plus a large number of naval pilots assigned to instruction duties in the extremely important naval air training program.. It was only piecemeal and with the greatest reluctance that the Naval General Staff finally granted these requests, and it was not until mid- October, 1941, that the necessary flying personnel were finally assembled.
Since the Task Force was scheduled to leave southern Japan for its northern rendezvous on November 17, this delay in assembling the necessary flight crews meant that it had only about one month’s training and practice as a unit before the strike was launched. It made intensive use of this time. A narrow land-locked stretch of water similar in depth and in surrounding terrain to Pearl Harbor was discovered in Kagoshima Bay in southern Kyushu. Late in October the air crews held repeated and very realistic maneuvers in this area. They ascertained with great precision the operational techniques appropriate to such confined spaces, and, in the case of the torpedo-plane pilots, even decided the optimum course, speed and altitude for releasing their missiles. It is interesting to note, even so, that their commanders continued up to the last moment to express serious and obviously heartfelt doubts as to the pilots’ and bombardiers’ abilities, doubts which, unhappily, were completely unjustified.
III
The Strike
On November 16, 1941 the Pearl Harbor Task Force, under the command of Vice-Admiral Nagumo Chuichi, rendezvoused at Saeki Bay, a secluded naval port on the Bungo Straits in eastern Kyushu. It was composed in the main of units from the First Air Fleet, plus the first section of Battleship Division 3 of the Combined Fleet and ancillary units.
The heart of the Task Force consisted of six of Japan’s newest and finest aircraft carriers,—Carrier Divisions 1 (the flagship Akagi and the Kaga), 2 (Hiryu and Soryu) and 5 (Shokaku, Zuikaku) of the First Air Fleet. These carried a complement of 360 planes—40 torpedo bombers, 135 dive bombers, 104 horizontal bombers and 81 strafing planes. They were protected by two fast battleships, the Hiei and the Kirishima, and a screen composed of two heavy cruisers (Tone, Chikuma), one light cruiser (Abukuma), eight destroyers and three submarines. They were accompanied on part of the outward voyage by a train consisting of at least three oilers and one supply ship. Among the aircraft carriers, one, the Zuikaku, was so new that she had completed her shakedown cruise only on September 25, 1941. The Shokaku was not much older.
On the morning of November 17 all units of the Task Force, except the Kaga, left Saeki Bay singly or in small groups and sailed northwards by various routes. Their destination was the isolated harbor of Hitokappu Bay (also known as Tankan or Tan- kappu Bay) on the southern coast of Etorofu, a bleak and desolate island in the Kuriles. It would be difficult to imagine a more secure rendezvous. Located far north of the shipping routes, the island was normally reached only from Japanese controlled ports in Hokkaido. It was rocky, barren and inhabited only by a few fishers, hunters and Ainu. There by November 24 the ships of the Task Force rendezvoused. The crews were busy with final preparations for the strike.
On the morning of November 26 the Task Force sailed. The submarines and destroyers fanned out far ahead as a screen and the heavier units followed in a double column. They cruised eastwards at moderate speed, economizing their fuel and accommodating their pace to the supply train, towards the standby position at 42°N and 170°E. Complete radio silence was observed lest they reveal their position to American communications intelligence. Earlier, the additional precaution had been taken of transferring the regular radio operators from these ships to naval operating bases in the Inland Sea, there to maintain a normal communications pattern and schedule and thus to mislead U.S. naval intelligence as to the location of their units
There was small chance in these deserted sub-arctic seas that the Task Force would encounter any hostile shipping, either naval or merchant. It was far to the north of normal steamship lanes. Still the possibility of detection had been anticipated, and Admiral Nagumo was under orders to attempt drastic evasive action if notified by the screen of the approach of a foreign vessel. If this failed and the Task Force was detected, he was to turn back if discovery occurred prior to X-l Day; if later, the decision as to whether to proceed or not was left to his judgment.
The outward voyage was uneventful. The sea was reasonably calm and the ships had no difficulty refueling. On December 2 the crews were officially informed of the nature of their mission, and a spirit of intense but subdued excitement became general. The same night all ships were darkened and the watch and ready crews increased. The standby position—42°N and 170°E—was reached on December 4 as scheduled. Here all combat ships fueled to capacity and the supply train turned back.
That night the Task Force altered course southeastward towards Hawaii and increased speed. The Chief of Staff, Vice Admiral Kusaka Ryunosuke, worried constantly—one moment lest the United States Fleet not be at Pearl Harbor, the next lest he somehow miss a message announcing the success of diplomatic negotiations and the recall of the attack. On December 5-6 (Japanese time) he was eased of the latter concern at least by the receipt of a message from the Chief of Division 1 of the Naval General Staff announcing that there was no hope for a diplomatic victory. Admiral Kusaka was greatly relieved.
The night of December 6-7 (Hawaii time) the Task Force put on full steam and raced towards Pearl Harbor at 26 knots. The men were at general quarters, the gun crews closed up and ready for action. Momentarily they expected detection and swift counterattacks. The carriers hummed with activity, readying the planes for a dawn take-off. Shortly before dawn several reconnaissance planes took off. They were scheduled to arrive over the harbor thirty minutes before the attack was to begin. With their departure, nerves grew still more taut. Discovery now seemed inevitable.
At 6 a.m., December 7 (Hawaii time) the Task Force reached a point 200 miles north of Oahu. Simultaneously dawn broke and the first wave of torpedo and dive bombers rose from the decks of the racing carriers. The Pearl Harbor strike was launched.
Far to the south a second and far less well-known element of the attacking forces was also closing in on Pearl Harbor. This was the Advance Expeditionary Force consisting of about 20 I-class submarines temporarily detached from the Sixth Fleet and placed under the command of Admiral Nagumo, commander of the Task Force.
The greater part of this submarine force had left the Inland Sea about November 17 and proceeded first to Kwajalein in the Marshall Islands and then to its operational area off Hawaii. A few elements were assigned to scouting duties around the Aleutians, Fiji and Samoa until X-3 Day. The main force began its approach to Hawaii on X-5 Day, sending a single submarine ahead to reconnoiter. On the night of December 6-7 (Hawaii time) they moved in and took up waiting positions covering the mouth of the channel leading to Pearl Harbor and a wide sweep of waters in the vicinity. Their mission was to block egress from the attacked harbor and to engage any American warships encountered—a mission wholly in accord with the Japanese naval doctrine of using their submarines in direct support of fleet actions. They were, however, under strict orders not to attack until the strike by the Task Force’s planes was actually under way.
The most novel aspect of this part of the Pearl Harbor plan was undoubtedly the use of the famous midget submarines. These were small two-man vessels, extremely cramped and uncomfortable, but apparently quite maneuverable and capable of prolonged submersion. They were equipped with an adapted version of standard torpedo tubes, and thus were not, as is sometimes claimed, designed as underwater kamikaze. In a broader sense, however, they were suicide craft, since none of their crews expected to return alive.
On the night of December 6 five of these midget submarines were launched from specially equipped fleet submarines some fifty miles off Pearl Harbor. Their mission was hazardous to an extreme and meant almost certain death. They were to steal through the guarded channel leading to Pearl Harbor, take up the best offensive positions possible, and then taking advantage of the general excitement and confusion caused by the air attack, to surface and discharge their torpedoes at the most tempting targets available. It was a daring and dangerous plan, and we are still not sure of the precise extent to which it succeeded. It seems probable—but not certain—that only one of the five midget submarines penetrated any distance up the channel leading to Pearl Harbor. This one discharged its torpedoes without effect and was promptly discovered and destroyed. The experience of the other four is not known in detail. An ensign from one of them was captured when his submarine went aground off Bellows Field. None rejoined the Japanese fleet.
Similarly, precise information as to the effectiveness of the Japanese submarine screen off Pearl Harbor is also lacking. Actually they appear to have had small opportunity of going into action. The effectiveness of the air attack was so great that very few American ships were able to get under way, clear the narrow channel leading out of Pearl Harbor, and reach open water. A few destroyers did, and, in at least one instance, one of them engaged an unidentified submarine immediately outside the entrance channel, but the probability is that this was another of the midgets. A number of the Japanese submarines, however, continued their patrols in the Hawaiian area after the air attack had ended. One of them even launched its aircraft to reconnoiter Pearl Harbor and ascertain the extent of the damage inflicted. Thereafter, several appear to have been assigned to raiding duties between Hawaii and the west coast of the United States. It was one of this group which appeared off the Oregon coast about December 13. The main body of the submarine force presumably returned to Kwajalein or Japan for assignment to further duties.
IV
The Aftermath
The story of the Pearl Harbor attack itself has frequently been told. The Japanese planes came over in three waves, starting at 7:55 a.m. and ending at 9:45, a total of one hour and 50 minutes. First came torpedo and dive bombers. The former did the most damage of all. Then came a wave of high- level bombers and finally another round of dive-bombers.
The attack was a success beyond the wildest expectations of Admiral Yamamoto’s most sanguine staff officer. The element of surprise was complete. When the planes withdrew, we had lost or suffered severe damage to eight battleships, three light cruisers, three destroyers and four miscellaneous vessels. 188 planes were destroyed. 2,396 American lives were lost; casualties totalled 3,435. This had cost the Japanese five midget submarines, a loss of 29 of the 360 planes participating, and about 68 lives.
Its mission accomplished, Admiral Nagumo’s Task Force withdrew at full speed to the northwest. The planes returned between 10:30 and 1:00 (Hawaii time). The main body of the Task Force then proceeded by a rather circuitous route to the great naval base at Kure on the Inland Sea, several units being detached en route, however, to participate in the attack on Wake Island.
Thus ended what may be considered the most brilliantly planned and executed naval- air strike in modern history. It is surely one of the cheapest major military victories on record. In a purely technical sense it will long stand as a classic example of the rewards of a daring offensive strategy. In a far broader sense, however, it should serve as a warning to those who expound the theory of the one-punch war. Pearl Harbor was a victory only in a short-term technical sense. Historically, it was a prelude to utter defeat.
1. Names are given in Japanese fashion with surname first.
2. All dates and times are Eastern Hemisphere time, unless designated otherwise, and the reader should make adjustments accordingly. Thus the Pearl Harbor attack occurred on December 7 our time, but December 8 Japanese time.