Chapter IV:
The Fatal Turn

Be audacious and cunning in your plans, firm and persevering in their execution, determined to find a glorious end.


The summer of 1941 was a crucial one for both Japan and the United States. Over a period of several years American planners had devised a strategy designed to protect the Western Hemisphere against Axis aggression and, if the United States was forced into war, to throw the bulk of its resources against Germany. But this strategy assumed, first, that Japan could be deterred from aggression by means short of war, and second, that in the event hostilities in the Far East could not be avoided, the United States would accept the loss of American territory in that area. The planners, unwilling to face the unpleasant prospect of large-scale military operations in the western Pacific, accepted these assumptions. But there were many, including the President and his Secretary of War, who found the conclusions of military logic distasteful and sought a way out of the dilemma. The solution provided by the advocates of air power turned American eyes once more to the Far East.

The crisis facing the Japanese leaders was more serious. In their view the very existence of the nation depended on their decisions. There seemed to be no way to end the war in China and economic restrictions were crippling their efforts to stockpile strategic materials and prepare the nation for any eventuality. Japan was truly at the crossroad.

The July Crisis

Negotiations to settle the issues between Japan and the United States had been in progress since February, 1941 when Ambassador Nomura had arrived in Washington. By summer, little progress had been made. The American position had been defined early in the conversations by Mr. Hull:

  1. Respect for the territorial integrity and the sovereignty of each and all nations.

  2. Support of the principle of noninterference in the internal affairs of other countries.

  3. Support of the principle of equality, including equality of commercial opportunity.

  4. Nondisturbance of the status quo in the Pacific except as the status quo may be altered by peaceful means.

But so long as the Japanese persisted in pursuing an aggressive policy in China and in southeast Asia there was not, in Mr. Hull's words, "one chance in twenty or one in fifty or even one in one hundred


of reaching a peaceful settlement."1

In the year since Prince Konoye had become Premier (16 July 1940), the Japanese had achieved two of the four objectives outlined in the "General Principles."2 The Tripartite Pact had been signed on 27 September 1940, and a neutrality pact concluded with Russia on 13 April 1941. Expansion by diplomacy had failed everywhere, except in Thailand. By agreement with Vichy France, Japan had obtained the right to military occupation of Tonkin Province and the use of air bases and military facilities in northern Indochina. But the Dutch, backed by the Americans and British, had stubbornly resisted Japanese efforts to gain economic concessions, and the Chinese showed no disposition to lay down their arms and accept Japanese terms for a settlement.

The German invasion of the Soviet Union on 22 June 1941 had a profound effect on the international situation and led the Japanese to re-examine the policy established only a year earlier. There was much heated discussion among Japanese political and military leaders of the probable effect of the Russo-German war, discussions which the Americans learned about through the medium of MAGIC3 and which President Roosevelt characterized as "a real drag-down and knock-out fight . . . to decide which way they are going to jump -- attack Russia, attack the South Seas . . . [or] sit on the fence and be more friendly with us." Foreign Minister Matsuoka favored the first course, the Army the second, and Premier Konoye inclined toward the third course. Finally, on 2 July 1941, an Imperial Conference, consisting of the chief members of the government and the armed forces meeting with the Emperor, made the final decision on Japan's future course.4

The question of a Soviet attack was put to rest by the Imperial Conference which decided that, regardless of any change in the international situation, Japan would adhere to the Tripartite Pact and to its plan for expansion to the south. If a favorable opportunity arose to take advantage of the war between Germany and the Soviet Union, Japan would be ready to do so. The negotiations with the United States were to be continued while preparations to place the nation on a war basis and strengthen its defenses were to be pushed forward with vigor. Also, steps were to be taken to bring about Chiang's surrender, and plans for the domination of Thailand and Indochina were to be executed immediately. "We will not be deterred," the Imperial Conference decreed, "by the possibility of being involved in a war with England and America."


The problems posed by Germany's attack on the Soviet Union were hardly settled and the decision made to abide by the Tripartite Pact and continue the drive southward when a new crisis arose. Still unanswered was the note Hull had handed Nomura on 21 June, asking for some clear indication of a genuine desire for peace and making allusions to the pro-German attitude of certain members of the Japanese Government. Matsuoka, the foremost advocate of the alliance with Germany, insisted on an outright rejection of the note and the termination of the talks. Premier Konoye, fearful that a flat rejection would end the negotiations, wished to reply with counterproposals already prepared by the Army and Navy. Matsuoka would not budge from his position and Konoye, given the nod by Tojo and after consultation with the Emperor, moved to oust the pro-German Foreign Minister. First, on 16 July, he submitted the resignation of the entire Cabinet to the Emperor. Two days later he received the Imperial mandate to form a new Cabinet. This he did by selecting the same ministers as before except for Matsuoka, whom he replaced with Admiral Toyoda. The Japanese could now go ahead with the program outlined at the Imperial Conference of 2 July.

The first move of the new government was the virtual occupation of French Indochina. Protesting that Indochina was being encircled, Japan issued what was in effect an ultimatum to the Vichy Government on 19 July. On the 24th, Roosevelt offered to guarantee to the Japanese equal access to the raw materials and food of Indochina in return for the neutralization of that country Nothing came of the proposal. The following day Japanese troops moved into the southern portion of Indochina. Japan now possessed strategically located air and naval bases from which to launch attacks on Singapore, the Philippines, and the Netherlands Indies.

Although the French acquiesced in this raid on their empire, the United States was not so obliging. In the view of the State Department, this fresh Japanese aggression constituted a threat to American interests in the Far East and justified the imposition of additional economic restrictions, then being considered by the President, as a warning to Japan. These restrictions were finally put into effect on 26 July when the President issued an order freezing Japanese assets in the United States. Since Japan no longer had the dollars with which to purchase the urgently needed materials of war, the effect of this measure, which the British and Dutch supported, was to create an economic blockade of Japan. The "obvious conclusion" of the "vicious circle of reprisal and counter-reprisal," wrote Ambassador Grew, "is eventual war," and Admiral Stark took so serious a view of the situation that he warned Admiral Thomas C. Hart, commander of the Asiatic Fleet, on the 25th, to take "appropriate precautionary measures against possible eventualities."5

The sharp American and British reaction to their move into Indochina


GENERAL SUZUKI president of the Japanese Planning Board, 1941.

came as a surprise to the Japanese and precipitated an intensive review of the nation's readiness to wage war. The picture was not encouraging. The powerful Planning Board which co-ordinated the vast, complex structure of Japan's war economy found the country's resources meager and only enough, in view of the recent action of the United States, for a quick, decisive war to gain the riches of the Southern Area. "If the present condition is left unchecked," asserted Teiichi Suzuki, president of the board, "Japan will find herself totally exhausted and unable to rise in the future." The blockade, he believed, would bring about Japan's collapse within two years, and he urged that a final decision on war or peace be made "without hesitation."6 The Navy's view was equally gloomy. There was only enough oil, Admiral Nagano told the Emperor, to maintain the fleet under war conditions for one and a half years and he was doubtful that Japan could win a "sweeping victory" in that time. His advice, therefore, was that every effort should be made to reach a peaceful settlement with the United States.

By the middle of August the two services had agreed on a broad line of strategy. The impetus came from a series of studies presented by the Total War Research Institute, a subordinate body of the Cabinet.7 Forecasting the course of events during the next six months, the institute called for the invasion of the Netherlands Indies in November, followed the next month by surprise attacks on British and American possessions in the Far East. Anticipating that the United States and Great Britain would utilize Soviet bases in a war against Japan, the institute predicted that Russia, too, would become involved in the war, probably between April and October 1942. The bulk of the institute's studies, however, dealt with the problems of economic mobilization; military planning, except in the most general sense, was left to the services.8

These studies, as well as others, were used as reference material by the General Staffs in developing their own plans during the tense days that followed the embargo. From these discussions emerged four alternative lines of strategy,



all of them designed to accomplish the swift destruction of Allied forces in the Far East and the early seizure of the Netherlands Indies. The first was based on the institute's studies and provided for the seizure of the Indies and then of the Philippines and Malaya. The second called for a step-by-step advance from the Philippines to Borneo, then Java, Sumatra, and Malaya. The reverse, from Malaya to the Philippines, constituted a third line of action and one which would have the advantage of delaying attack against American territory. The fourth plan proposed at this time consisted of simultaneous attacks against the Philippines and Malaya followed by a rapid advance along both axes to the Indies. Admiral Yamamoto's plan for an attack against Pearl Harbor, work on which had begun in January, did not enter into the calculations of the planners at this time.

Army and Navy planners agreed that the first plan was too risky for it would leave Japanese forces exposed to attack from the Philippines and Malaya. The Navy preferred the second plan; it was safe, provided for a step-by-step advance, and created no serious problems. The Army objected to it, however, on the ground that by the time the main objectives in the Netherlands Indies and Malaya were reached the enemy would have had time to strengthen his defenses. The third plan, with its early seizure of Malaya and bypassing of the Philippines, appealed greatly to the Army planners, who hoped in this way to gain Southeast Asia and delay American entry into the war. But this course, as the Navy pointed out, also placed American naval and air forces in the Philippines in a strategic position athwart Japan's line of communication and constituted a risk of the utmost magnitude. The fourth course, simultaneous attacks and advance along two axes, created serious problems of co-ordination and timing and a dangerous dispersion of forces. But because it was the only course which compromised the views of both groups, it was finally adopted. For the first time the Japanese had a strategic plan for offensive operations designed to achieve the goals of national policy against a coalition of enemies.9

America Faces the Far East

By mid-August 1941, American military strategy for the Pacific and Far


East -- which reflected the determination to avoid war with Japan and to remain on the defensive even if it meant the loss of the Philippines, Guam, and Wake -- no longer reflected the policy of the U.S. Government. There had been signs even before RAINBOW 5 was completed that American policy toward Japan was stiffening. The President's action in May making China eligible for lend-lease had marked the beginning of a shift in Far Eastern policy. Though it proved difficult to find any munitions to furnish China because early plans for lend-lease had been made entirely in terms of aid to Britain, by July the principle of arming a compact Chinese Army and Air Force with American weapons had been accepted with all the implications this had for relations with the Japanese. In addition, a mission under Brig. Gen. John Magruder was dispatched to China to aid in delivery of materials over the Burma Road and to assist the Chinese both in using the materials received and in placing orders properly. Magruder did not, however, have authority to discuss military plans with the Chinese, nor was he told what he should do if war broke out between the United States and Japan.10

The order of 26 July freezing Japanese assets in the United States and establishing a de facto oil embargo gave further confirmation of America's stiffening policy toward Japan. The planners had objected to the move on the ground that it might force Japan into war to gain the oil it so badly needed and thus imperil American interests in the Atlantic.12 The President believed too, as he had written Secretary of the Interior Harold L. Ickes earlier in the month, that "it is terribly important for the control of the Atlantic for us to help to keep peace in the Pacific," but felt, after the German attack on the Soviet Union had in effect lessened the immediate danger in the Atlantic and freed Japan to move south, that the United States could take a stronger stand in the Pacific. This conviction, shared by Stimson and others, was a basic factor in the decisions made during the months before Pearl Harbor.

A strong policy called for larger forces and for a revision of military plans. These were not long in coming. On the same day the oil embargo was imposed, General MacArthur, since 1936 the Military Adviser of the Philippine Commonwealth and architect of the Philippine Army, was recalled to active duty and given command of all U.S. Army Forces in the Far East (USAFFE) . At the same time, by executive order, the Philippine Army was called into the service of the United States.13 But it was the RAINBOW strategy and not the President's desire to strengthen American defenses that dictated the instructions sent to MacArthur. Except for approximately 400 reserve officers to assist in training


the Philippine Army, he was told, he would not receive any reinforcements.

On the last day of July, only two days after he had told MacArthur not to expect any reinforcements, Marshall radically altered the Army position "to go to no further expense for permanent improvements unless savings will result." American policy, he told his staff, was to defend the Philippines, and presumably to reinforce them, but not to such an extent as to "jeopardize the success of the major efforts made in the theater of the Atlantic."14 This scarcely constituted a reversal of the RAINBOW 5 strategy, but it did justify approval of a proposal to reinforce the Philippines with guns, tanks, and ammunition.

This shift was not as sudden as it appeared. There had been earlier proposals to reinforce the Philippines, most of which had been rejected only because of a lack of funds. The previous year President Manuel Quezon, with the support of the Philippine Department commander, had sought to secure additional money for Philippine defense by using the sugar excise funds -- a project which required Congressional approval -- and early in 1941 the strength of the Philippine Scouts had been doubled. Moreover, Secretary Stimson, who had served as governor-general of the Philippines and had long advocated a firm attitude toward Japan, favored the reinforcement of the islands, as did other men in high places. But it was the airmen's argument that their long-range bomber, the B-17, could do what the Navy could not that convinced the more skeptical and paved the way for a new view of the defense of the Philippines. A force of these bombers based in the Philippines, it was contended, would not only serve to defend the islands but would constitute such a threat to Japanese movements southward toward the Netherlands Indies as to deter Japan from further aggression in that direction.

The air staff proposal was approved early in August and on the 14th the War Plans Division of the General Staff submitted a program for reinforcing the Philippines with antiaircraft artillery, modern combat planes, and tanks "to enhance the probability of holding Luzon, and, in any event, giving a reasonable assurance of holding Manila Bay."15 General Marshall gave the plan his approval and then notified MacArthur that he would receive 1 coast artillery regiment, 1 battalion of tanks, an ordnance company, and 31 P-40's sometime in September, and shortly after that another 50 P-40's directly from the factory. At the same time the Air Corps allocated 4 heavy bomber and 2 pursuit groups to MacArthur's Far East Air Force and ordered a provisional squadron of 9 B-17's from Hawaii to the Philippines. These planes, after a historic pioneer flight from Oahu by way of Midway, Wake, Port Moresby, and Darwin, reached Clark Field on 12 September. By this time the reinforcement of the Philippines enjoyed the highest priority in the War Department.

During the months that followed, aircraft, weapons, supplies, and men in increasing numbers were marked for shipment to the Philippines. But it took time to get orders filled, pack and ship them to the ports, find the vessels


to transport them, and sail them across the ocean. At every step of the way there were delays, but none so serious as the shortage of cargo ships. By November the backlog in U.S. ports of equipment marked for the Philippines amounted to approximately one million tons. Though a shipping schedule that provided for additional sailings in the next two months was established, a considerable quantity of supplies and a large number of men destined for the Philippines never got there.

The decision to reinforce the Philippines brought into sharp focus the problem of developing a trans-Pacific air route less exposed than the one via Midway and Wake. Airmen had long urged such a project, which had the additional advantages of guarding the line of communication to Australia and New Zealand and providing protection for surface vessels along the sea lanes of the South Pacific, but did not gain approval until August 1941. Construction was begun in October, when funds were made available, and by the time war came the route across the South Pacific by way of Christmas, Canton, Samoa, Fijis, and New Caledonia was nearing completion.16

The prevailing mood in Washington in the fall of 1941 was one of optimism over the possibility of defending the Philippines. It was the opinion of the Joint Board, expressed at the meeting of 19 September, that the reinforcements planned would have a profound strategic effect in a Pacific conflict and might well be the decisive element in deterring Japan from opening hostilities.17 All that was needed was time to prepare. The general estimate was that preparations would be completed by March 1942. Until that time there was a risk that the Japanese would attack, but it was a risk the Army planners were apparently willing to take.

The view that Japan would not strike until the spring of 1942 was based on careful studies of the Far Eastern situation. Japan, it was assumed, wished to gain control of Asiatic Russia, China, and Malaysia, and would, if conditions were favorable, resort to war to gain its aims. The Philippines, strategically located along the path of Japan's southward course, would be one of the early objectives in a war with the United States. Thus far Japan had hesitated to seize these territories, the Army planners believed, because of Soviet Russia's unexpected and successful showing against the Wehrmacht, because of economic pressure from the United States, Great Britain, and the Netherlands, and because of the continued resistance of the Chinese Nationalists. Moreover, in the opinion of the planners, the conquest of the Philippines would be so costly an operation that Japan "will hesitate to make the effort except as a last resort." The more formidable the Philippine defenses, therefore, the less likelihood was there of a Japanese war. "Air and ground units now available or scheduled for dispatch to the Philippine Islands in the immediate future," concluded the


planners, "have changed the entire picture in the Asiatic Area."18

Though the major assumptions and conclusions of RAINBOW5 were still valid, its provisions for the defense of the Philippines were obviously in need of revision. Drawn up on the assumption that the islands could not be reinforced and that their loss was probable, it called for a limited defense of the entrance to Manila Bay by the existing garrison and local forces. MacArthur's recall to active duty and the induction of the Philippine Army into the service of the United States, and the new view of the defensibility of the islands and their role as a base for air operations against Japan, were eloquent testimony that events had once more outrun plans. In a strong letter to the War Department General MacArthur pointed out these facts, asserting that he would soon have a force of approximately 200,000 men organized into eleven divisions and a greatly strengthened air force. The time had come, he believed, to reject the "citadel type defense" of the Orange and RAINBOW plans in favor of an active defense of the entire archipelago.19

This proposal, so in accord with the new optimism over the defense of the Philippines, met with favor in the War Department and then in the Joint Board which on 21 November approved a revision of RAINBOW 5. In this revision, the mission of the Philippine garrison was expanded to include "all the land and sea areas necessary for the defense of the Philippine Archipelago," that is, of the entire Philippines and not only Manila Bay. Moreover, the existence of a greatly enlarged air force in the Philippines was recognized by the provision for air attacks against "Japanese forces and installations within tactical operating radius of available bases." How far some of the planners had moved from their original defensive concept is perhaps most strikingly revealed in the first draft of a letter to MacArthur which the planners prepared for General Marshall. Air reinforcements, they wrote, had modified the conception of purely defensive operations "to include strong offensive air action," a phrase which Marshall prudently changed to "strong air operations in the furtherance of the strategic defensive."20 But words could not gloss over the fact that the B-17 was an offensive weapon and that a force of heavy bombers in the Philippines had only one purpose -- offensive operations. Marshall himself acknowledged this fact in an off-the-record press interview when he indicated "that though the last thing the United States wants is a war with the Japanese," it was preparing for "an offensive war against Japan," a war which would be waged "mercilessly everywhere in the Pacific."21

Though the Japanese did not wait until the spring of 1942 to open hostilities and MacArthur did not receive all that had been promised him, the Philippine garrison constituted in December 1941 a far stronger force than it had six months earlier. The strength of the ground forces, exclusive of the Philippine


Army, had been increased by 8,563 men and now numbered 31,095. The ten reserve divisions of the Philippine Army had been two-thirds mobilized but were still poorly equipped and inadequately trained. The air force had been strengthened and reorganized. At Clark Field were 35 B-17's and scattered among the various fields on Luzon were over 100 P-40's. Much remained to be done to create a balanced air force, but the Philippines had nevertheless a larger number of modern combat aircraft than any other overseas base, including Hawaii and Panama.

Even the Asiatic Fleet had been reinforced, despite the Navy's assertion earlier in the year that it would not be. No major surface elements, it is true, had been added but Admiral Hart had received an additional squadron of PBY's for a total of 32, 6 motor torpedo boats, and 18 submarines, most of them of the latest type, giving him all together a fleet of 29 underwater craft. In addition, he had 1 heavy and 2 light cruisers, 13 old destroyers of World War I vintage, 6 gunboats, and miscellaneous vessels. Also under his command was the 4th Marine Regiment, withdrawn from China at the end of November.

The most powerful American force in the Pacific was the Pacific Fleet, based at Pearl Harbor and consisting of 9 battleships, 3 aircraft carriers, 12 heavy and 8 light cruisers, 50 destroyers, 33 submarines, and 100 patrol bombers. In addition, British and Dutch vessels in Far Eastern waters could be expected, in the event of war with Japan, to fight the common foe. Thus, the Allies could muster a naval force of considerable strength to oppose the Japanese Combined Fleet. Unfortunately, all efforts to work out a plan for concerted naval action in the Far East proved unsuccessful.

American bases along the line of communications between Hawaii and the Philippines had also been strengthened in 1941, but still represented little more than token forces. Guam, whose fortification had been recommended by the Hepburn Report in 1938 but denied by Congress, was still "practically defenseless against determined attack."22 Its garrison was composed of 365 Marines, a small force of natives, and a navy consisting of three patrol boats; weapons included nothing larger than the .30-caliber machine gun. The defense of Wake Island, for which Congress had appropriated funds on the recommendation of the Hepburn Board, was a case, like that of the Philippines, of too little and too late. Construction was still in progress on 7 December but there was one Marine fighter squadron of twelve Grumman Wildcats on the island, and a 388-man detachment of the 1st Marine Defense Battalion armed with 5-inch coastal guns, 3-inch and .50 caliber antiaircraft guns, .30-caliber machine guns, and small arms. The largest group on the island were civilians, 70 Pan American Airway employees and over 1,000 construction men. Midway, the "sentry for Hawaii" and, in the opinion of the Hepburn Board, second in importance only to Pearl Harbor, had since mid-1940 been garrisoned by a small Marine force. In the summer of 1941 a naval air station was established on the island and in September the 6th Defense Battalion with 784 officers and men relieved the original garrison. The planes destined for Midway were embarked on the


Lexington on 5 December, to be delivered on the morning of the 7th, but other events intervened and they did not arrive until the 17th.23


While the Navy, with Army air forces, provided the first line of defense in the Pacific, the Army, with certain exceptions, provided the forces to defend those bases from which ships and planes operated. The most important of these lay along the triangle Alaska-Hawaii-Panama. Not only were they vital bases but they constituted the strategic frontier of the United States and the outer defenses of the west coast. Of these, only Hawaii, 2,000 miles distant from San Francisco, lay in the Pacific and figured in the plans for offensive operations against Japan in the event of war; Alaska and Panama, though fully as important, were more closely associated with hemisphere defense plans.

The planners had recognized early that the chief danger to Hawaii lay not so much in an effort by the Japanese to capture the islands, but rather in a sudden and unexpected attack, probably from the air, on the great naval base at Pearl Harbor. This thought had appeared from time to time in studies and estimates and was included in the local plans for defense.24

The transfer of the U.S. Fleet to Pearl Harbor in April 1940 and its retention there on the President's orders, a move designed to deter the Japanese, increased enormously the problems of defending the naval base and the growing number of airfield installations. During the summer and fall of 1940, Maj. Gen. Charles D. Herron repeatedly urged that heavy bombers and antiaircraft defenses, including artillery, and air warning equipment, be sent to Hawaii, and that bomb-proof shelters be built. The Navy, too, was concerned about the protection of its base from a surprise carrier-based air attack, and Secretary Knox gave strong support to Herron's requests in a letter to Stimson in January 1941. All were agreed on the danger and sought, within the limitations imposed by appropriations, to provide what was needed. But at that time Hawaii was the best equipped American base and had high priority for modern aircraft, antiaircraft guns, air warning


equipment, and barrage balloons. There was little more, Stimson assured Knox, that could be done except to provide for closer co-ordination between the Army and Navy.


When Lt. Gen. Walter C. Short assumed command of the Hawaiian Department in February 1941 -- at the same time that Admiral Husband E. Kimmel took over the Pacific Fleet -- General Marshall carefully defined his mission for him as the protection of the naval base and the fleet, and warned against allowing service feuds to interfere with joint defense plans. Short continued along the lines already marked out, pushing construction of airfields, the air warning system, dispersal areas, and gun installations. In April he and Kimmel submitted a revised plan for the defense of Oahu which carefully specified the responsibilities of each of the services. Included with the plan was the Army and Navy air commanders' estimate which, with remarkable prescience, outlined the probable course of a Japanese attack as a sudden air raid against ships and installations on Oahu, coming without warning and originating from carriers not more than 300 miles distant. "In a dawn attack," they foretold, "there is a high probability that it could be delivered as a complete surprise in spite of any patrols we might be using."25

By December 1941, the Army garrison in Hawaii had been considerably reinforced and was in many respects the strongest base in the Pacific. Assigned to its ground defense were 2 understrength infantry divisions, 4 antiaircraft artillery regiments, almost 4 complete coast artillery regiments, and company of light tanks, with supporting service troops. Of the total of 234 aircraft, only about half were operational. Included in this total were a large number of obsolescent types and only six B-17's. The air warning system, though not yet completed, consisted of six mobile radar sets and three fixed stations in place but not completely installed.

The Plan for War

Despite repeated assertions of a willingness to go to war to gain its objectives, the Japanese Government in July had drawn back quickly in the face of the unexpectedly strong reaction from the United States. Contributing to this


JAPANESE MOCK-UP OF FORD ISLAND AND BATTLESHIP ROW, Pearl Harbor, used in Japanese table-top maneuvers.

lack of resolution was the slowing down of Germany's advance in Russia and the Japanese Navy's concern over the shortage of oil reserves. From the end of July until his resignation in October, Premier Konoye sought to persuade his Cabinet colleagues to adopt a less aggressive policy in an effort to reach agreement with the United States.

The first sign of this new policy was a proposal, delivered by Admiral Nomura in Washington on 6 August, for a personal meeting, a "leaders' conference," between the Premier and President Roosevelt. War Minister Tojo had agreed to this proposal only on the understanding that Konoye would use the occasion to press the program for expansion to the south. The American reply on the 17th that a prerequisite to such a meeting was the settlement of the issues between the two countries confirmed Tojo and the Army leaders in their view that the United States would never yield to the Japanese demands and that war should begin as soon as the Army and Navy were ready.

The difference between Konoye's and Tojo's views was temporarily resolved early in September and formalized at an Imperial Conference held on the 6th of the month. The agreement was characteristically Japanese and expressed in language both sides could accept and interpret in their own way. The negotiations with the United States, it was


agreed, would be continued, as Konoye wished. But at the same time, military preparations would be pushed to completion so that the nation would be ready for war by the end of October, that is, in six weeks. "If by the early part of October," the conferees decided, "there is no reasonable hope of having our demands agreed to in the diplomatic negotiations . . . we will immediately make up our minds to get ready for war. . . ."26

The Imperial Conference also fixed the minimum demands Japan would make and the maximum concessions it would grant in the negotiations with the United States and Great Britain. The minimum demands Japan asked were, first, both the Western Powers would promise to discontinue aid to China, close the Burma Road, and "neither meddle in nor interrupt" a settlement between Japan and China; second, America and Britain would recognize Japan's special position in French Indochina and agree not to establish or reinforce their bases in the Far East or take any action which might threaten Japan; and third, both nations would resume commercial relations with Japan, supply the materials "indispensable for her self-existence," and "gladly cooperate" in Japan's economic program in Thailand and Indochina. In return for these "minimum demands" the Japanese were willing to agree not to use Indochina as a base for further military advance, except in China; to withdraw from Indochina "after an impartial peace" had been established in the Far East; and, finally, to guarantee the neutrality of the Philippine Islands.27

While negotiations went forward, the Army and Navy General Staff continued their preparations for war and the troops earmarked for operations in the south intensified their training, usually under conditions approximating those of the areas in which they would fight. Since agreement had already been reached on the strategy for war, General Sugiyama, Chief of the Army's General Staff, was able shortly after the 6 September Imperial Conference, to direct that detailed operational plans for the seizure of Malaya, Java, Borneo, the Bismarck Archipelago, the Netherlands Indies, and the Philippines be prepared.28 The Army planners immediately went to work and the next two months witnessed feverish activity in the General Staff.

By the end of August the Navy staff had worked out plans for seizing bases in the western Pacific, and had from Admiral Yamamoto a separate plan for an attack on Pearl Harbor. "Table-top maneuvers" at Tokyo Naval War College between 10-13 September resulted in agreement on operations for the seizure of the Philippines, Malaya, the Netherlands Indies, Burma, and islands in the South Pacific. But there was still some doubt about Yamamoto's plan. The exercise had demonstrated that a Pearl Harbor strike was practicable, but many felt that it was too risky, that the U.S. Pacific Fleet might not be in port on the day of the attack, and that the danger of


The Japanese Plan for War: December 1941


discovery during the long voyage to Hawaii was too great. But Admiral Yamamoto refused to give up his plan and finally, when he failed to convert his colleagues, offered to resign from the Navy. The combination of his strong argument that the success of the southward drive depended on the destruction of the American fleet, his enormous prestige, and his threat to resign were too much for opponents of the plan. In mid-October, a month after the maneuvers, the Navy General Staff finally adopted his concept of a surprise carrier-based attack on Pearl Harbor and incorporated it into the larger plan for war.29

This larger plan, which was virtually complete by 20 October and was the one followed by the Japanese when war came, had as its immediate objective the capture of the rich Dutch and British possessions in southeast Asia, especially Malaya and the Netherlands Indies. To secure these areas, the Japanese believed it necessary to destroy or neutralize the U.S. Pacific Fleet at Pearl Harbor, and to deprive the United States of its base in the Philippines. America's line of communications across the Pacific was to be cut by the seizure of Wake and Guam. Once the coveted area to the south had been secured, Japan would occupy strategic positions in Asia and in the Pacific and fortify them immediately. These bases were to form a powerful defensive perimeter around the newly acquired southern area, the home islands,


and the vital shipping lanes connecting Japan with its sources of supply.30

The area marked for conquest formed a vast triangle, whose east arm stretched from the Kuril Islands on the north through Wake, to the Marshall and Gilbert Islands. The base of the triangle was formed by a line connecting the Marshall and Gilbert Islands, the Bismarck Archipelago, Java and Sumatra. The western arm extended from Malaya and southern Burma through Indochina, and thence along the China coast. (Map 1)

The acquisition of this area would give to Japan control of the resources of Southeast Asia and would satisfy the national objectives in going to war. Perhaps later, if all went well, the Japanese believed, the area of conquest could be extended. But there is no evidence in the Japanese plans of an intention to defeat the United States. Japan planned to fight a war of limited objectives and, having gained what it wanted, expected to negotiate for a favorable peace.

Operations to secure these objectives and others would begin on the first day of war, when Japanese military forces would go into action simultaneously on many fronts. Navy carrier-based aircraft would attack the U.S. Pacific Fleet in the Hawaii area. Immediately after, joint Army and Navy air forces would strike American air and naval forces in the Philippines, while other Japanese forces hit British Malaya. After these simultaneous attacks, advance Army units were to be landed at various points in Malaya, the Philippines, and British Borneo. The results thus obtained were to be immediately exploited by large-scale landings in the Philippines and in Malaya, followed by the rapid occupation of those areas. At the same time, Thailand was to be "stabilized," Hong Kong seized, and Wake and Guam occupied. The conquest of the Bismarck Archipelago would follow the seizure of the last two islands.

During this first period, Army and Navy forces were to seize advance air bases in the Celebes, Dutch Borneo, southern Sumatra, the Moluccas, and Timor. The bases thus seized were to be immediately utilized for air attacks on Java, while other preparations for the invasion of that island were speedily completed.

With the U.S. Fleet and the Philippines neutralized, and with advance bases in the Netherlands Indies, the Japanese would move against Java and Sumatra. Taking Singapore under fire from the land side, that is, from Malaya, Japanese forces would first invade and occupy this British bastion. Once that fortress was reduced, the Japanese would move on to northern Sumatra, in preparation for the drive on Java. Meanwhile, other Japanese forces moving southward through the Netherlands Indies were to join those in Sumatra in the final attack on Java.

While Java was being occupied, the Japanese would complete their seizure of Sumatra and capture air bases on the southern tip of Burma at the earliest possible moment. If conditions were favorable they would then push on in Burma and occupy the Andaman and Nicobar Islands in the Indian Ocean. Operations in China would be continued throughout this period in order


to maintain "the present strategic situation."31

The occupation of the Netherlands Indies would complete the first period of the war and would, the Japanese estimated, require five months. The Philippines they expected to take in 50 days, Malaya in 100, the Indies in 150. After that time the Japanese would consolidate their position and strengthen the bases along the perimeter of their newly gained empire in order to repulse any Allied effort to penetrate this defensive ring or threaten the vital area within it. During this period the Army would continue its operations in China and Burma and establish a system of administration for the southern area.

The Navy's plan for the period after the initial operations was to intercept with a strong force anticipated trans-Pacific operations of U.S. naval forces. Its plan lists as "areas expected to be occupied or destroyed" eastern New Guinea, New Britain, the Fiji Islands, Samoa, the Aleutians, Midway, and "strategic points in the Australia area."32 But operations to seize these objectives were not authorized by Imperial General Headquarters until the spring of 1942.

Japanese planners anticipated that certain events might require an alteration in their strategy and outlined alternative courses of action. The first possibility was that Japanese-American negotiations then in progress would prove successful. If this unexpected success was achieved, all operations were to be suspended, even if the final order to attack had been issued. The second possibility was that the United States might take action before the attack on Pearl Harbor by sending elements of the Pacific Fleet to the Far East. In that event, the Combined Fleet would be deployed to intercept American naval forces. The attacks against the Philippines and Malaya were to proceed according to schedule.

If the Americans or British launched local attacks, Japanese ground forces were to meet the attack and air power was to be brought into the area to destroy the enemy. These local operations were not to interrupt the execution of the general plan, but if the United States or Great Britain seized the initiative by opening operations first, Japanese forces were to await order's from Imperial General Headquarters before beginning their assigned operations. The possibility of a Soviet attack, or of a joint United States-Soviet invasion from the north, was also considered by the Japanese planners. To meet such a contingency, Japanese forces in Manchuria were to be strengthened. Should this attack materialize the Philippine and Malay operations were to proceed as planned, while air units were to be immediately transferred from the home islands or China to destroy Russian air forces in the Far East. Ground forces were to be deployed to Manchuria at the same time to meet Soviet forces on the ground.

The forces required to execute this vast plan for conquest were very carefully calculated by Imperial General Headquarters. (Chart 1) A large force had to be left in Manchuria, and an even larger one in China. Garrisons for




Korea, Formosa, Indochina, and the defense of the home islands required additional forces. Thus, only a small fraction of the Japanese Army was available for operations in the south. Of the total strength of the Army's 51 divisions, cavalry group, 59 mixed brigades, and 1,500 first-line planes, Imperial General Headquarters could give the Southern Army, which had the mission of carrying out all these operations, only 11 divisions and the bulk of 2 air groups with approximately 700 planes.

The Japanese allocated their forces for the initial operations only after a careful estimate of the enemy forces.33 In the Philippines, the Japanese correctly estimated there was a U.S. Army garrison (exclusive of Scouts) of 22,000 men and 110,000 Philippine Army troops. The air strength in the islands was thought to consist of 270 planes of all types, 70 of which were heavy planes. The British were thought to have in Malaya alone 90,000 troops, and in Burma another 35,000. Dutch ground forces in the Indies were estimated to number 85,000 men. The total enemy ground strength was placed at 447,000 men, including British, American, Dutch, and Thailand troops. This figure did not include Chinese, Indian, Australian, and New Zealand troops. The total enemy air strength, the Japanese estimated, consisted of 1,249 aircraft distributed as follows: Malaya, 330; Burma, 60; Philippine Islands, 270; Netherlands Indies, Thailand, 177; China, 130. The Hawaiian air force was not included in the Japanese estimates.

American naval strength was overestimated. The Japanese believed there were 5 carriers in the Pacific area. They placed 2 cruisers, 1 heavy and 1 light, in the Asiatic Fleet, and another 3 in the Pacific Fleet, which was thought to contain also 11 battleships, 84 destroyers, and 30 submarines. The submarine force in Philippine waters was estimated at 17 underwater craft. Their estimate of British and Dutch naval forces was equally inaccurate.

In the execution of this complicated and intricate plan, the Japanese planners realized, success would depend on careful timing and on the closest co-operation between Army and Navy forces. No provision was made for unified command of all services. Instead, separate agreements were made between Army and Navy Fleet commanders for each operation. These agreements provided simply for co-operation at the time of landing and for the distribution of forces.

In addition to supporting the Army's operations in the south, the Combined Fleet had other important missions. Perhaps the most important, and certainly the most spectacular, was that assigned the Pearl Harbor Striking Force. Later, this force was to support operations of the 4th Fleet and then assist in the southern operations. The 6th Fleet (submarines) was to operate in Hawaiian waters and along the west coast of the United States to observe the movements of the U.S. Pacific Fleet and destroy lines of communication by surprise attacks on shipping. The 5th Fleet was to patrol the waters east of Japan, in


readiness for enemy surprise attacks, and, above all, to keep on the alert against Russia.

The Japanese plan for war was complete in all respects but one -- the date when it would go into effect. That decision awaited another more important decision: whether or not Japan would go to war. The answer was not long in coming.


Table of Contents ** Previous Chapter ** Next Chapter


1. Pearl Harbor Attack: Report of the Joint Committee on the Investigation of the Pearl Harbor Attack, Doc. 244, 79th Cong., 2d sess. (hereafter cited as Pearl Harbor Report), p. 294. Unless otherwise noted, this section is based on the Pearl Harbor Report; Pearl Harbor Attack Hearings, pt. 20, Memoirs of Prince Konoye; IMTFE, Judgment, pp. 924-35; Department of State, Foreign Relations of the United States, Japan, II, 342, 527-38, 549-55; Political Strategy Prior to Outbreak of War, pt. IV, Japanese Studies in World War II, 150. The most detailed accounts in secondary sources are Langer and Gleason, The Undeclared War, and, on the Japanese side, Feis, The Road to Pearl Harbor.

2. See above, ch. II.

3. Code given to the interception and decoding of the Japanese messages [both diplomatic and military. The primary diplomatic cipher was code-named PURPLE; the primary naval cipher was known as JN-25].

4. Ltr, Roosevelt to Harold L. Ickes, 1 Jul 41, cited in Langer and Gleason, The Undeclared War, p. 646. The 2 July decision is included among IMTFE Exhibits, 588. See also Ltr, Grew to author, 19 Jun 49, OCMH.

5. Rad, CNO to CINCAF, 25 Jul 41, in Pearl Harbor Attack Hearings, pt. 14, pp. 1400-1401; Grew Diary, July, 1941, cited in Langer and son, The Undeclared War, p. 654. Admiral Stark opposed a total embargo on oil at this time, but did favor a partial embargo that would provide Japan with enough for essential peacetime needs, but none for military purposes. Ltr, Stark to Col Warren G. Hoover, Actg Chief of Mil Hist, 5 Aug 59, OCMH.

6. Political Strategy Prior to Outbreak of War, pt. IV, Japanese Studies in World War II, 150, pp. 73-77.

7. This group was established in October 1940 to conduct research into wartime measures, in co-operation with the Planning Board.

8. IMTFE, exhibits 870, 870-A, and 871.

9. Political Strategy Prior to Outbreak of War, pt. IV, Japanese Studies in World War II, 150, pp. 9-10.

10. Rpt, JPC to JB, Aircraft Rqmts for Chinese Govt, 9 Jul 41, JB 355, ser. 691; U.S. Mil Mission to China, 12 Sap 41, JB 354, ser. 716; Mins, JB Mtg, 12 Jul 41. For a full account of prewar policy toward China, see Riley Sunderland and Charles F. Romanus, Stillwell's Mission to China, UNITED STATES ARMY IN WORLD WAR II (Washington, 1953), ch. 1.

11. Memo, Turner for Stark, 19 Jul 41, sub: Study of Effect of Embargo . . . , Pearl Harbor Attack Hearings, pt. 5, pp. 2382-84.

12. Ltr, Roosevelt to Ickes, 1 Jul 41, cited in Langer and Gleason, The Undeclared War, p. 646.

13. For an account of these measures, and of the reinforcement of the Philippines which followed, see Morton, The Fall of the Philippines, chs. II and III.

14. Gerow's Office Diary, entry of 31 Jul 41, OPD Exec Files; Phil Dept Def Proj, 1940, May 41, OPD Reg. Docs.

15. Memo, Gerow for CofS, 14 Aug 41, sub: Reinforcement of Phil, WPD 3251-55.

16. For a full account of the development of this route, see Wesley Frank Craven and James Lea Cate, eds., Plans and Early Operations--January 1939 to August 1942, "The Army Air Forces in World War II," vol. I (Chicago: The University of Chicago Press, 1948) (hereafter cited as AAF I), pp. 180-82; AAF, Hist Study 9. The Development of the South Pacific Air Route, pp. 23-28, Air Hist Office.

17. Mins, JB Mtg, 19 Sep 41.

18. Memo, Gerow for Secy of War, 8 Oct 41, sub: Strategic Concept of the Phil Is, WPD 3251-60.

19. Ltr, MacArthur to TAG, 1 Oct 41, sub: Opns Plan R-5, WPD 4178-18.

20. Ltr, CofS to CG USAFFE, 21 Nov 41, sub: U.S.-British Cooperation in the Far East, with Incl, extract of changes in RAINBOW 5, WPD 4402-112.

21. Notes on Conf in OCofS, 15 Nov 41, copy in OCMH. The quotation is not General Marshall's but is from the notes of the meeting.

22. Hepburn Report, p. 27.

23. Lt. Col. Robert D. Heinl, Jr., The Defense of Wake (Washington: U.S. Marine Corps Historical Section, 1947), pp. 4-11; Marines at Midway (Washington: U.S. Marine Corps Historical Section, 1948), pp. 3-9, 16.

24. Watson, Prewar Plans and Preparations, pp. 465-75.

25. Joint Estimate of Army and Navy Air Action, 31 Mar 41, Pearl Harbor Attack Hearings, pt. 15, exhibit 44, p. 1437; Pearl Harbor Report, pp. 83-84; ltr, Marshall to Short, 7 Feb 41, WPD 4449-1.

26. Konoye Memoirs, Pearl Harbor Attack Hearings, pt. 20, pp. 4022-23. The wording of this important statement varies in different documents. IMTFE Doc. 1579 give a slightly different working as does IMTFE Judgment, ch. VII, p. 939. The Japanese phrase "kaiseno ketsui su" may be translated literally "decide to open hostilities." Konoye apparently did not interpret the phrase as meaning that it was a decision for war; Tojo did.

27. Ibid., IMTFE Doc. 1652, exhibit 588.

28. IMTFE exhibit 2244, deposition of Tanaka.

29. For a full account of the evolution of the Pearl Harbor plan see Robert E. Ward, "The Inside Story of the Pearl Harbor Plan," U.S. Naval Institute Proceedings, LXXVII, No. 12 (December 1951), pp. 1272-81.

30. This account of the Japanese plan is based on a number of documents which, together with the plan, are described in Morton, The Fall of the Philippines, pp. 51-55.

31. Hist of Army, Sec, Imperial GHQ, Japanese Studies in World War II, 72, p. 16.

32. Combined Fleet Top Secret Operational Order 1, 5 Nov 41, in Pearl Harbor Attack Hearings, pt. 13, p. 438.

33. Army estimates are based on Hist of Army Sec, Imperial GHQ, Japanese Studies in World War II, 72, pp. 12, 18-22; Navy estimates on Political Strategy Prior to Outbreak of War, pt. V, same series, 152, pp. 19-20. The estimates are for November 1941: the first source.

Transcribed and formatted for HTML by Patrick Clancey, HyperWar Foundation