Title banner: Pearl Harbor * Why, How, Fleet Salvage and Final Appraisal

Imminence of War


The numerous diplomatic discussions in Washington, and the many exchanges of diplomatic notes and proposals were not fruitful in lessening the gap between Japan's adamant demands and America's vigorous opposition. Analysts of the facts could readily see that the two countries were on a collision course which could only result in hostilities. However, the American public was far from convinced that the actual situation could be so extreme, and continued to put great faith in the negotiations which had been going on in Washington for eight or nine months. Whether or not these diplomatic efforts were bona fide on the part of Japan might now be doubted. Unquestionably the United States could have delayed the conflict for a time by agreeing to the various demands of the Japanese. These demands were so extreme that Japan did not expect full agreement, but nevertheless pursued the policy of diplomatic exchanges until the last. Even the attacking force had instructions to withhold the attack in case the diplomats came to an agreement.

It is fair to say that the great majority of the people, even in the military services, did not visualize a direct attack by Japan. Rather it was taken for granted that Japan would move toward the south which was rich in oil and other resources. There were some who felt that Japan would take the Russian maritime provinces to the northward. This was especially so since this region was greatly desired by the Japanese Army, but Russia was still unconquered by Germany and Japan did not want that nation to be counted as an enemy at that time.

However, the policies and actions of Japan were dominated by the extreme militarists headed by Premier General Tojo. Their estimate of the situation was so favorable that they were determined that now there had been presented to them a "golden opportunity" to strike and accomplish their purposes. Their treaty of alliance with Germany and Italy gave them full confidence because at that time the Axis Powers were eminently success-


ful. France had fallen, Great Britain was wobbling, Hitler's army was near the gates of Moscow, Rommel's German army was overrunning Egypt, the Near East was threatened, and the United States stood alone in remonstration without any formal allies.


The information received from the Japanese after the war shows that their methodical observations and espionage kept them well informed of everything concerning the defenses of Hawaii and the activities of the Pacific Fleet. In our open democratic society Japanese agents were free to observe fleet practices, take photographs with their high-powered equipment, and to solicit almost any information desired. Any person could roam the hills around Pearl Harbor or other areas of Hawaii and witness the comings and goings of each and every ship, exactly where they were moored while in port, and what their schedules seemed to be. Also, such persons could readily obtain specific information on the air fields and various defense measures such as anti-aircraft guns, torpedo nets around ships, and barrage balloons. High-powered binoculars were hardly necessary, but they showed particular details which in large measure were unknown even to any single officer of the fleet. In fact, one of the espionage officers in the Japanese Consulate has admitted that he rented a plane at a commercial airport of Honolulu and regularly flew over Hawaii's military air bases. He also stated that he watched fleet sorties from Mount Tantalus or from Aiea.

Testimony before the Roberts Commission and the Congressional Investigation showed that the Japanese Consulate in Honolulu was headquarters for an espionage ring. There, was at least one German spy. At that time there were about 37,000 Japanese aliens in Hawaii and some 117,000 American citizens of Japanese ancestry.

The Consulate's spy ring was unbelievably effective. Tokyo asked for and received regular reports from the Consulate at Honolulu and from other Pacific ports regarding the movements of ships, their specific location in port, air reconnaissance, defense measures, troop movements, and other matters. As 7 December drew near, such reports were requested by Tokyo at shorter intervals, and they were furnished as requested. The exchanges were numerous and intensely interesting. Here are excerpts from a few


typical examples. These may be seen in their entirety in Part 12 of the Congressional Investigation of Pearl Harbor.

From Honolulu to Tokyo 16 January 1941:

* * * * *

2. The number of vessels seen in the harbor on the morning of the 16th was as follows: five battleships . . . five light cruisers . . . nineteen destroyers, two destroyer tenders . . . about six small submarines . . . and three transports.

The Yorktown is not in port.

The CinCUS shifted the flag from the New Mexico to the Pennsylvania on 15 January. [Trans. 1/31/41]

From Honolulu to Tokyo 21 February 1941:

1. The capital ships and others departed from Pearl Harbor on the 13th and returned on the 19th. (It is said that they will depart again on the coming Wednesday and return on the following Wednesday). Judging from the statements by various sailors who were on these vessels, the training was apparently held in the vicinities of Kauai, Lahaina and Hilo. [Trans. 2/28/41]

* * * * *

From Tokyo to Honolulu 21 September 1941:

Henceforth, we would like to have you make reports concerning vessels along the following lines insofar as possible: [The message divides Pearl Harbor waters into a number of areas which are delineated.]

2. With regard to war ships and aircraft carriers, we would like to have you report on those at anchor . . . tied up at wharves, buoys and in docks. (Designate types and classes briefly. If possible we would like to have you make mention of the fact when there are two or more vessels alongside the same wharf.) [Trans. 10/9/41)

From Tokyo to Honolulu 15 November 1941:

As relations between Japan and the United States are most critical, make your 'ships in harbor report' irregular, but at a rate of twice a week. Although you already are no doubt aware, please take extra care to maintain secrecy. [Trans. 12/3/41]

From Tokyo to Honolulu 29 November 1941:

We have been receiving reports from you on ship movements, but in future will you also report even when there are no movements. [Trans. 12/5/41]


From Tokyo to Honolulu 2 December 1941:

In view of the present situation, the presence in port of warships, airplane carriers, and cruisers is of utmost importance. Hereafter, to the utmost of your ability, let me know day by day. Wire me in each case whether or not there are any observation balloons above Pearl Harbor or if there are any indications that they will be sent up. Also advise me whether or not the warships are provided with anti-mine nets. [Trans. 12/30/41]

From Honolulu to Tokyo 4 December 1941:

On the afternoon of the 3rd one British gunboat entered Honolulu harbor. She left port early on the morning of the 4th ....

Furthermore, immediately after the vessel entered port a sailor took some mail to the British Consular Office and received some mail in return. [Trans. 12/12/41]

From Honolulu to Tokyo 5 December 1941:

1. During Friday morning, the 5th, the three battleships mentioned in my message {previously) arrived here. They had been at sea for eight days.

2. The Lexington and five heavy cruisers left port on the same day.

3. The following ships were in port on the afternoon of the 5th: 8 battleships, 3 light cruisers, 16 destroyers. [Trans. 12/10/41]

* * * * *

From Tokyo to Honolulu 6 December 1941:

Please wire immediately . . . the movements of the fleet subsequent to the fourth. [Trans. 12/12/41]

From Honolulu to Tokyo 6 December 1941:

1. On the American Continent in October the Army began training barrage balloon troops at Camp Davis, North Carolina. Not only have they ordered four or five hundred balloons, but it is understood that they are considering the use of these balloons in the defense of Hawaii and Panama. In so far as Hawaii is concerned, though investigations have been made in the neighborhood of Pearl Harbor, they have not set up mooring equipment, nor have they selected the troops to man them. Furthermore, there is no indication that any training for the maintenance of balloons is being undertaken. At the present time there are no signs of barrage balloon equipment. In addition, it is difficult to imagine that they have actually any. However, even though they have actually made preparations, because they must control the air over the water and land runways of the airports in the vicinity of Pearl Harbor, Hickham, Ford and Ewa, there are limits to the balloon defense of Pearl Harbor. I imagine that in all probability there is consider-


able opportunity left to take advantage for a surprise attack against these places.

2. In my opinion the battleships do not have torpedo nets . . . . [Trans. 12/8/41]

From Honolulu to Tokyo 6 December 1941:

. . . The following ships were observed at anchor on the 6th:

9 battleships, 3 light cruisers, 3 submarine tenders, 17 destroyers, and in addition there were 4 light cruisers, 2 destroyers lying at docks (the heavy cruisers and airplane carriers have all left).

2. It appears that no air reconnaissance is being conducted by the fleet air arm. [Trans. 12/8/41]

The diplomatic codes used by the Japanese in the exchange of communications regarding Pearl Harbor and the fleet became known to us, but at the time of the attack most of their military codes were still secure. Actually they used a number of different codes and changed them occasionally. Also, they devised a system to report movements of fleet ships by the display of lights at night. The lights would be at certain land areas in Hawaii, and these could be observed by Japanese submarines on surveillance patrol off shore. The exact time of display and the number of lights shown would identify the type and number of large vessels which had departed, or were about to depart, from Pearl Harbor.

Another method was to include in regular news broadcasts certain information regarding the breaking off of diplomatic relations. This was known as the "hidden word" method. The intended message was clear when the key was understood and applied.

Tokyo sent out to their embassies throughout the world the key to a weather report message to give advance information to its agents of the impending termination of diplomatic relations with particular countries. This was done by adding a "ringer" in the weather report, and repeating it three or more times. Thus "east wind rain" referred to the United States-Japan relations; "west wind clear" to the British; and "north wind cloudy" to the Russians.

Clearly, the Japanese informational system gave specific knowledge on the American structure of defense. The Pacific Fleet situation prior to the attack was almost an open book to Japan. Their complete information permitted them to provide each attacking plane with a specified target and its exact location in the harbor. Sketches on official Navy charts were


Image: USN 416885 Fleet Admiral Ernest J. King, USN. He was appointed Commander-in-Chief of the United States Fleet on 20 December 1941 and assumed command on 30 December 1941
USN 416885
Fleet Admiral Ernest J. King, USN. He was appointed Commander-in-Chief of the United States Fleet on 20 December 1941 and assumed command on 30 December 1941


recovered from Japanese airplanes and midget submarines which were shot down or captured during the attack.


Most Americans have traditionally frowned upon espionage and spying as sources of information pertinent to our security and military defense. Consequently we had but little knowledge comparable to the knowledge Japan had regarding Pearl Harbor and our defenses. The United States' representatives in Japan were greatly restricted in obtaining definite information, as indeed were all foreigners, in the totalitarian atmosphere which prevailed there. Rumors were rife and there was plenty of evidence that Japan was intent on a great program of expansion of military capabilities. Yet we lacked details on how much had been accomplished in augmenting their naval and air power, and the training of operating personnel. We were yet to learn, to our sorrow, how extensive their preparations had been and how proficiently their manpower had been developed and trained.

It was still an American tendency, and indeed a world-wide one, to underrate the Japanese. For instance, we rated them as excellent copyists, but lacking in originality; we smirked at the stories of some of their ships having capsized at launching; some accepted the myth that because of their eye structure the Japanese could never be good combat aviators. Events soon proved that such ignorance of a prospective enemy might be termed the "valor of ignorance" because our misconceptions produced a false sense of security, a feeling of over-confidence, and a presumed inherent superiority.

From many sources, however, we knew beyond question that Japan would strike when the circumstances suited her, but nobody knew when, where, or how. Her plans and the execution of them were closely guarded secrets which were known to only a few within the Japanese government or among her military strategists.

As has been seen, there had been rumors of an attack on Pearl Harbor. But there were also rumors on many other targets and it seemed far-fetched and foolhardy to attack Hawaii, especially without a suitable declaration. Why would Japan attack such a concentration of American power nearly 3,500 miles away while its real objectives in the Far East were near at hand and almost defenseless?


In addition to Southeast Asia and the Dutch East Indies, Japan coveted the maritime provinces of Russia bordering on the Pacific. This fact was widely recognized, and now with Hitler's army near to Moscow, that move seemed quite logical to military analysts, especially as it was known that the Japanese Army was particularly anxious to occupy those areas. And after all, the Army was running the government, which was headed now by General Tojo.

The imminence of hostile action pointed to attacks in the Western Pacific area. There seemed to be little probability that the initial attack could be against Pearl Harbor. This was the current estimate of the situation among American officials. There was no person "in the know" who had forecast an attack on Pearl Harbor. The secret knowledge in possession of the United States in Washington at the time supported the generally-held viewpoint that Japan's first move would be in the Western Pacific.

For over a year many of the Army and Navy radio stations had been able to intercept, and certain ones to decode, most of the Japanese secret diplomatic messages. This was indeed an accomplishment of the highest value. It gave our government the basic information concerning Japanese conversations with Germany and Italy, and even Tokyo's instruction to its diplomats in Washington. Such information was referred to as "magic," and pertained specifically to the diplomatic code which was designated as "purple." Credit for the remarkable achievement of breaking this code goes to both Navy and Army personnel, and was carried to the point of actually being able to manufacture machines for coding and decoding "purple" messages.

The diplomatic messages did not contain specific warning of the attack on Pearl Harbor. Even the Japanese diplomats in Washington were kept entirely uninformed of that military project. They were purposely kept from military secrets so that they would continue their diplomatic efforts without giving an inkling of what the military had in mind.

At that time we had not completely broken the Japanese military codes. Even if they had been in our possession at the time of Pearl Harbor it would not have been of great assistance because the attack was handled in strict secrecy with complete radio silence. Inasmuch as the objectives of Japan with reference to their program in Asia, as well as their relationships to Germany and Italy, were well documented by these many exchanges, let us set down as interesting sidelights a few excerpts from the numerous "purple" messages printed in Part 12 of the comprehensive Hearings Before the joint Committee on the Investigation of the Pearl Harbor Attack.


From Tokyo to Berlin 2 July 1941:

* * * * *

The Policy.

1. Imperial Japan shall adhere to the policy of contributing to world peace by establishing the Great East Asia Sphere of Co-prosperity, regardless of how the world situation may change.

2. The Imperial Government shall continue its endeavor to dispose of the China incident, and shall take measures with a view to advancing southward in order to establish firmly a basis for her self-existence and self-protection. [Trans. 8/8/41] [1]

From Tokyo to All Diplomatic Offices 26 July 1941:

Depending upon how Japanese relations with England and the United States turn out, we may have to consider divesting England and the United States of all their interests in China. If and when things come to the worst, I want all areas concerned to cooperate in either destroying or seizing the considerable mining and other industrial equipment and ships of these countries. Be particularly sure to let nothing be taken away. I want you all to be ready at any moment to take this precautionary step of transferring the property of these two nations to our control. [Trans. 7/28/41] [2]

From Nomura in Washington to Tokyo 30 July 1941:

Today I knew from the hard looks on their faces that they meant business and I could see that if we do not answer to suit them that they are going to take some drastic steps.

During my first conversation with Roosevelt after I took office the President, referring to the Panay incident, said that at the time he cooperated with the Secretary of State and succeeded in restraining popular opinion but that in case such a thing happened a second time, it would probably be quite impossible to again calm the storm. The latest incident brought all this back to me and I can see just how gravely they are regarding it. Think of it! Popular demand for the freezing of Japanese funds was subsiding and now this had to happen. I must tell you it certainly occurred at an inopportune moment. [Trans. 8/2/41] [3]

From Tokyo to Embassy in Washington 31 July 1941:

We are expanding our best efforts to cooperate with Germany. She knows it and ought to understand our actions.

6. Well, the formula for cooperation between Tokyo and Berlin, in order to realize the fundamental spirit of the Tripartite Pact, should be for each


country to have a certain flexibility in its conduct. What I mean to say is that each should understand that real cooperation does not necessarily mean complete symmetry of action. In other words, we should trust each other and while striving toward one general objective, each use our own discretion within the bounds of good judgment.

Thus, all measures which our Empire shall take will be based upon a determination to bring about the success of the objectives of the Tripartite Pact. That this is a fact is proven by the promulgation of an Imperial rescript. We are ever working toward the realization of those objectives, and now during this dire emergency is certainly no time to engage in any light unpremeditated or over-speedy action. Please send to Rome. [Trans. 8/4/41] [4]

From Tokyo to Japanese Embassy in Washington 16 October 1941:

Although I have been requested by both the German and Italian Ambassadors in Tokyo to give them confidential information on the Japanese-American negotiations, I have, in consideration of the nature of the negotiations, been declining to do so. However, early this month, following the German attacks on American merchant ships and the consequent (revival?) of the movement for revision of the Neutrality Act, the German authorities demanded that the Japanese Government submit to the American Government a message to the effect that the Japanese Government observes that if the ROOSEVELT Administration continues to attack the Axis Powers increasingly, a belligerent situation would inevitably arise between Germany and Italy on the one hand and the United States on the other, and this would provide the reasons for the convocation of the duties envisioned in the Three Power agreement and might lead Japan to join immediately the war in opposition to the United States. . . . [Trans. 10/17/41] [5]

From Tokyo to Washington 22 November 1941:

. . . Stick to our fixed policy and do your very best. Spare no efforts and try to bring about the solution we desire. There are reasons beyond your ability to guess why we wanted to settle Japanese-American relations by the 25th, but if within the next three or four days you can finish your conversations with the Americans; if the signing can be completed by the 29th, (let me write it out for you-twenty ninth); if the pertinent notes can be exchanged; if we can get an understanding with Great Britain and the Netherlands; and in short if everything can be finished, we have decided to wait until that date. This time we mean it, that the deadline absolutely cannot be changed. After that things are automatically going to happen. Please take this into your careful consideration and work harder than you ever have before. This,


for the present, is for the information of you two Ambassadors alone. [Trans. 11/22/41] [6]

From Washington to Tokyo 27 November 1941:

On the 27th, I, together with Ambassador Kurusu, called on the President. (Secretary Hull was also present.) The resume of our talks follows:

The President: "In the last Great War, Japan and the United States were together on the side of the Allies. At that time, both Japan and the United States were given ample proof that Germany failed to comprehend the way the people of other countries think.

"Since these conversations were begun, I am aware of the fact that much effort has been made by the Japanese side, too, by those who cherish peace. I am highly appreciative of this fact. It is clear that the majority of the American people are anxious to maintain peaceful relations with Japan. I am one of those who still harbors much hope that Japanese-U. S. relations will be settled peacefully."

I: "Your recent proposal will no doubt be the cause of painful disappointment to the Japanese Government."

The President: "To tell you the truth, I, too, am very disappointed that the situation has developed in the manner that it has. However, during the several months that these conversations were being conducted, cold water was poured on them when Japan occupied southern French Indo-China. According to recent intelligences, there are fears that a second cold water dousing may become an actuality." (He apparently meant the increase in our troops to French Indo-China and our occupation of Thai.) (See my message #1205.) "I fully understand that the general public in Japan who has been living in war conditions for the past year, cannot see a parallel with conditions in the United States, which is living under peaceful conditions.

"During all of the time, however, that Your Excellency and Secretary Hull have been conversing, we have never heard of or seen concrete proof of any peaceful intention by the leading elements of Japan. This has made these talks an exceedingly difficult undertaking." [Trans. 11/29/41] [7]

From Tokyo to Japanese Ambassador in Berlin 30 November 1941:

4. If when you tell them this, the Germans and Italians question you about our attitude toward the Soviet, say that we have already clarified our attitude toward the Russians in our statement of last July. Say that by our present moves southward we do not mean to relax our pressure against the Soviet and that if Russia joins hands tighter with England and the United States and resists us with hostilities, we are ready to turn upon her with all our


might; however, right now, it is to our advantage to stress the south and for the time being we would prefer to refrain from any direct moves in the north.

5. This message is important from a strategic point of view and must under all circumstances be held in the most absolute secrecy. This goes without saying. Therefore, will you please impress upon the Germans and Italians how important secrecy is.

6. As for Italy, after our Ambassador in Berlin has communicated this to the Germans, he will transmit a suitable translation to Premier MUSSOLINI and Foreign Minister CIANO. As soon as a date is set for a conference with the Germans and Italians, please let me know. [Trans. 12/1/41] [8]

* * * * *

From Berlin to Tokyo 29 November 1941:

* * * * *

1. Ribbentrop opened our meeting by again inquiring whether I had received any reports regarding the Japanese-U. S. negotiations. I replied that I had received no official word.

Ribbentrop: "It is essential that Japan effect the New Order in East Asia without losing this opportunity. There never has been and probably never will be a time when closer cooperation under the Tripartite Pact is so important. If Japan hesitates at this time, and Germany goes ahead and establishes her European New Order, all the military might of Britain and the United States will be concentrated against Japan.

"As Fuehrer Hitler said today, there are fundamental differences in the very right to exist between Germany and Japan, and the United States. We have received advice to the effect that there is practically no hope of the Japanese-U. S. negotiations being concluded successfully, because of the fact that the United States is putting up a stiff front.

"If this is indeed the fact of the case, and if Japan reaches a decision to fight Britain and the United States, I am confident that that will not only be to the interest of Germany and Japan jointly, but would bring about favorable results for Japan herself." [Trans. 12/1/41] [9]

* * * * *

From Tokyo to Japanese Ambassador in Berlin 30 November 1941:

3. The proposal presented by the United States on the 26th made this attitude of theirs clearer than ever. In it there is one insulting clause which says that no matter what treaty either party enters into with a third power it will not be interpreted as having any bearing upon the basic object of this treaty, namely the maintenance of peace in the Pacific. This means specifically the


Three-Power Pact. It means that in case the United States enters the European war at any time the Japanese Empire will not be allowed to give assistance to Germany and Italy. It is clearly a trick. This clause alone, let alone others, makes it impossible to find any basis in the American proposal for negotiations. What is more, before the United States brought forth this plan, they conferred with England, Australia, the Netherlands, and China -— they did so repeatedly. Therefore, it is clear that the United States is now in collusion with these nations and has decided to regard Japan, along with Germany and Italy, as an enemy. [Trans. 12/1/41] [10]

From Tokyo to Ambassador in Washington 1 December 1941:

When you are faced with the necessity of destroying codes, get in touch with the Naval Attachés office there and make use of chemicals they have on hand for this purpose. The Attaché should have been advised by the Navy Ministry regarding this. [Trans. 12/1/41] [11]

From Rome to Tokyo 3 December 1941:

On this day, at 11 o'clock in the morning, I, accompanied by Ando, called on Premier Mussolini, (Foreign Minister Ciano was also present). I described the developments in the Japanese-U. S. negotiations in accordance with the contents of your message #986 to Berlin.

Mussolini: "I have been carefully watching the progress of the Japanese-U. S. talks from the very beginning and therefore am not at all surprised to receive your report. As a matter of fact, in view of the utter bull-headedness of the United States and the meddlesome nature of President Roosevelt, I should say that the outcome was nothing but what should have been expected. One of the aims of the United States is to make the Far East her own, from an economic standpoint. I have felt from the beginning that if it was the intention of the United States to separate Japan from the Axis first and then intervene in Europe, the United States was doomed to fail because of Japan's loyal and sincere nature.

"As Your Excellency and Your Excellency's predecessor know, I wholeheartedly endorse Japan's policy of creating a New Order in East Asia. This has been true in the past, is true now and will be so in the future. I am one who is firmly convinced that Japan has every right to be the leader of the Great East Asia area."

I continued by relating to him the contents of your message referred to in the heading, (with regard to paragraph 3 of that message, I said that I had been advised that some arrangements were being made between our Ambassador in Berlin and Ribbentrop). With regard to paragraph 2, Mussolini said that should war break out, Italy would give every military aid


she had at her disposal, i.e., that she would make every effort to keep the British navy checked in the Mediterranean.

Mussolini: "Recently, the formation of an Italian-German air force bloc was discussed so as to afford closer cooperation between the two to apply further pressure on the British in the Mediterranean. The negotiations on this proposal have progressed to a point where it may be signed any day now."

Regarding paragraph 2 again, should Japan declare war on the United States and Great Britain, I asked, would Italy do likewise immediately? Mussolini replied: "Of course. She is obligated to do so under the terms of the. Tripartite Pact. Since Germany would also be obliged to follow suit, we would like to confer with Germany on this point."

With reference to paragraph 3, I submitted the French text of your message #987, as one proposal, and asked him whether he preferred it to be separately or jointly. He replied that as long as it was done simultaneously with Germany it did not make much difference to him, but if it were done jointly he thought it would give the impression of more strength . . . .

Mussolini failed to bring up the subject of Soviet Russia, so the matter was not brought up at all. [Trans. 12/6/41] [12]

* * * * *

The total group of "purple" messages showed that Japan was unwilling to give up her alliance with Germany and Italy, would not remove troops from Indo-China, and refused to abide by the American demands regarding China and free trade for U.S. nationals as guaranteed by commercial treaties.

The Japanese were quite unaware that the United States was in possession of their diplomatic code, and therefore able to read their communications. However, they fully realized that the various radio stations under the control of the United States were regularly monitoring the radio traffic of the Japanese Fleet. This was a customary practice among nations and furnished valuable information. One of the obvious advantages was the accumulation of sufficient information and data to enable cryptanalysts to eventually break the codes. It is now common knowledge that the military code of the Japanese was broken shortly after the Pearl Harbor attack, and this achievement was an incalculable benefit.

Another purpose of monitoring was to fix the location of the enemy's ships. This could be done quite handily by means of obtaining cross-bearings. For instance, each ship of the Japanese Fleet had a specific call signal. When that ship answered its call one could use a direction finder to ascertain its


Image: USN 424384 Admiral Harold R. Stark, USN, Chief of Naval Operations from 1 August 1939 to 12 March 1942.
USN 424384
Admiral Harold R. Stark, USN, Chief of Naval Operations from 1 August 1939 to 12 March 1942.

general location, and when several of our radio stations from distant areas did likewise, the cross-bearings on that ship would show its definite location. In many cases it would not even be necessary to get cross-bearings, especially when the habitual operations of the fleet vessels were understood.


For quite some time before 7 December the Pearl Harbor radio stations maintained a fairly accurate record of the location of the major units of the Japanese Fleet. This radio intelligence was reported to the Commander-in-Chief almost daily and was considered quite reliable until just prior to the attack, when its reliability was greatly reduced by counter measures taken by the Japanese. First they changed the call signals of their ships on 1 November, and then again on 1 December. This had been done before, and was confusing for a time but not usually for very long. Then the Japanese used deceptive call signals to give the impression that certain major ships like aircraft carriers were elsewhere than where they actually were. For several weeks in late November our monitoring stations lost contact with the Japanese carriers and some other major vessels. This gave rise to the suspicion that these ships might have taken up stations at the naval bases of the Mandated Islands.

The chief countermeasure to defeat monitoring is radio silence, and that is what the Japanese used so effectively. A certain amount of radio silence by the carriers was observed in the early stages of their preparations for the attack, and absolute radio silence was in effect for all ships of the attacking task force which assembled in northern Japan and sailed for Hawaii on 26 November 1941.


The probability of hostilities between the United States and the Axis Powers was well recognized by a large portion of the American public. But how this might come about, and when, was entirely speculative. The news media featured the growing tensions which existed in both the Atlantic and the Pacific, and even the Mediterranean, but few visualized that a direct attack on the United States was imminent. The general concept seemed to be that if we were drawn into the war it would be by going to the defense of a victimized area, such as Malaya or the Dutch East Indies.

In order to relieve the pressure on Malaya and other areas which were held by our allies, the American plan for a possible war with Japan was for the fleet to attack the Japanese Mandated Islands in the Marshalls and the Carolines and to establish a fleet base at Truk. But because of many problems and shortages, such an expedition was looked upon unfavorably by most naval officials. The American public of that time would not support a war of that nature. Then the Japanese solved this dilemma by making a direct attack on the American flag at Pearl Harbor.


The people of Hawaii, including the military, were accustomed to news reports showing the continuing controversy between opposing powers, but in Hawaii there was little turmoil or tension. Business went on routinely, people pursued their usual activities, and military personnel were carrying out the program of preparedness. There was little suspicion that Japan would launch a direct attack prior to a state of war, or at least an ultimatum, against the strong-hold of the Pacific. Among the military the prevailing talk seemed to be that if war should come it would be somewhere else, probably in the Southwest Pacific.

From official Washington there had come to Hawaii, as to other Pacific outposts, almost a superfluity of alarms and alerts for over a year. These were usually of a general nature as reflecting the new aggressions of Japan, or the widening gap in diplomatic relations. In most cases such warnings were precautionary and were not intended for public information. In fact the Hawaiian commanders were always cautioned to limit the warning information to those who needed to know, and to avoid arousing or irritating Japan by any overt or unfriendly action. The rank and file of the military, as well as the general public, were probably not aware of the serious implications which existed just prior to 7 December. And some of the most important implications were not known to the high commands in Hawaii because Washington had not transmitted them. The warning signals sent from Washington had value, but were lacking in important essentials. Naturally, in Washington they could not be specific enough to forecast what would happen. There were sometimes differences in the estimates of the situation between the Army and the Navy. Furthermore, the separate signals sent out by the Army and the Navy were received and evaluated separately in Hawaii. There was not unity of command but there was a remarkable degree of discussion and coordination regarding the information which was received. The first alert came from the War Department to the Hawaiian Army Command and to Panama in June 1940. The date marked the fall of France, indications of possible German aggression in South America, and also the Japanese bombing of Chungking. This alert continued for a month. The Navy was not included in the Washington instructions but was told of the situation locally, and participated by increasing its long-range air patrol and continuing it for some months. Washington cautioned Hawaii to avoid publicity or in any way from provoking curiosity of news media or alien agents.


In February 1941 the Secretary of the Navy advised the Secretary of War of the possibility of air attack on Pearl Harbor. Copies of this communication were received by the Army and by the Navy in Hawaii. In July 1941 Hawaii was warned of the tense situation caused by the Japanese occupation of Southern Indo-China and the United States' imposition of an embargo on trade with Japan.

When the Konoye cabinet fell in Japan and General Tojo took over the government as Premier in October 1941, the Hawaiian commands and other Pacific commands were again advised of the seriousness of the situation in the Pacific. This dispatch from the Chief of Naval Operations in Washington went to all commanders directly concerned. Admiral Kimmel issued a new security order under date of 14 October 1941 which superseded the security order which was in effect dated 15

Image: USN NR&L (MOD) 27377 Admiral Husband E. Kimmel, USN, Commander-in-Chief Pacific Fleet on 7 December 1941.
USN NR&L (MOD) 27377
Admiral Husband E. Kimmel, USN, Commander-in-Chief Pacific Fleet on 7 December 1941.


February 1941. This delineated actions to be taken in the anti-aircraft defense, anti-submarine defense, Army and Navy coordination, communications plans, drills, and so on. In his order Admiral Kimmel stated: "That no responsible foreign power will provoke war . . . by attack on the Fleet or Base, . . . [but] that a declaration of war may be preceded by; (1) a surprise attack on ships in Pearl Harbor, (2) a surprise submarine attack on ships in the operating areas, (3) a combination of these two." [13] This eventuality had been mentioned in the letter sent to the Secretary of War by the Secretary of the Navy in January 1941. It had also been covered in great detail by the Martin-Bellinger order for the defense of Pearl Harbor 31 March 1941. In that order it is stated: "In the past Orange [Japan] has never preceded hostile actions by a declaration of war." The Chief-of-Staff of Admiral Kimmel, Rear Admiral W. W. Smith, stated at the Hewitt Inquiry that "they were aware of the possibility of hostile action without a declaration of war, but they expected the Japanese might hit the Philippines, Midway, or Guam, but not Pearl Harbor." [14] This was the thought-universally held.

The Navy Department dispatch of 16 October 1941, was essentially as follows:

The resignation of the Japanese Cabinet has created a grave situation. If a new Cabinet is formed it will probably be strongly nationalistic and anti-American. If the Konoye Cabinet remains the effect will be that it will operate under a new mandate which will not include rapprochement with the U.S. In either case hostilities between Japan and Russia are a strong possibility. Since the U.S. and Britain are held responsible by Japan for her present desperate situation there is also a possibility that Japan may attack these two powers. In view of these possibilities you will take due precautions including such preparatory deployments as will not disclose strategic intention nor constitute provocative actions against Japan. [15]

On 24 November 1941, a message was received from the Navy Department as follows:

Chances of favorable outcome of negotiations with Japan very doubtful. This situation coupled with statements of Japanese Government and movements of their naval and military forces indicate in our opinion that a surprise aggressive movement in any direction including attack on Philippines or Guam is a possibility. Chief of Staff has seen this dispatch concurs and


requests action adees to inform senior Army officers their areas. Utmost secrecy necessary in order not to complicate an already tense situation or precipitate Japanese action. Guam will be informed separately. [16]

The final and most important warning was sent from Washington and to other Pacific outposts on 27 November 1941. It was specifically designated as a "war warning." It reads as follows:

This despatch is to be considered a war warning. Negotiations with Japan looking toward stabilization of conditions in the Pacific have ceased and an aggressive move by Japan is expected within the next few days. The number and equipment of Japanese troops and the organization of naval task forces indicates an amphibious expedition against either the Philippines Thai or Kra Peninsula or possibly Borneo. Execute an appropriate defensive deployment preparatory to carrying out the tasks assigned in WPL46. Inform district and Army authorities. A similar warning is being sent by War Department. SPENAVO inform British. Continental districts Guam Samoa directed take appropriate measures against sabotage. [17]

It is noted that at no time did Washington indicate any belief of a surprise air attack on Pearl Harbor in advance of a formal declaration of hostilities. On the contrary, the supposition continued to be that Japan's moves would be to the south, and evidence was at hand giving validity to such beliefs. This belief was supported by the fortnightly summary sent out from Washington under date of 1 December 1941 from the Director of Naval Intelligence. On the Japanese naval situation it stated:

Deployment of naval forces to the southward has indicated clearly that extensive preparations are underway for hostilities. At the same time troop transports and freighters are pouring continually down from Japan and northern China coast ports headed south, apparently for French Indo-China and Formosan ports. Present movements to the south appear to be carried out by small individual units, but the organization of an extensive task force, now definitely indicated, will probably take sharper form in the next few days. To date this task force, under the command of the Commander in Chief Second Fleet, appears to be subdivided into two major task groups, one gradually concentrating off the Southeast Asiatic coast, the other in the Mandates. Each constitutes a strong striking force of heavy and light cruisers, units of the Combined Air Force, destroyer and submarine squadrons. Although one division of battleships also may be assigned the major capital ship strength remains in home waters, as well as the greatest portion of the carriers.


The equipment being carried south is a vast assortment, including landing boats in considerable numbers. Activity in the Mandates, under naval control, consists not only of large reinforcements of personnel, aircraft, munitions but also of construction material with yard workmen, engineers, etc. [18]

Washington's acute desire to avoid war in the Pacific should also be noted. In fact both the War and Navy Departments expressed the hope in November 1941 that firm diplomatic attitudes toward Japan not be taken for a period of three months or more, during which time reasonable preparedness would be obtained. It was especially desired to improve defenses in the Philippines as it was recognized that the Japanese coveted this territory. Its location was critical to Japanese expansion. The United States was in process of adding a large number of B-17's to the air power of the Philippine Islands. Under date of 27 November 1941 General Marshall, the Army's Chief of Staff, and Admiral Stark, the Chief of Naval Operations, asked the President and Secretary of State for more time to prepare, stating: "The most essential thing now, from the United States viewpoint, is to gain time. . . . Precipitance of military action on our part should be avoided so long as consistent with national policy." [19]

Although the additional time was not to be, the fact was clear that the United States did not commit any overt military action against Japan. The final overt hostile act was Japan's treacherous bombing of Pearl Harbor with a consequent toll of destruction and human lives.


While Washington furnished to Hawaii and elsewhere a great volume of information on the critical relations between Japan and the United States, it is a fact that some very important information was not sent to Hawaii. This was the "purple" information regarding the specific ships in designated locations in Pearl Harbor during the few days prior to 7 December, and the instructions to various places to burn certain codes. However, it should be mentioned here that the work of decoding and translation of the multitude of messages was not completed until after 7 December. The amount


of work over-taxed the section in charge of this specialty and some of it was not completed until after the air attack.

At an earlier time, shortly after "purple" messages became available, the Fleet was an addressee for this information. But this was discontinued about six months before the attack in the interest of security. Obviously the value to our government of intercepting and reading Japanese secret diplomatic messages was so great that it would be foolhardy to risk any compromise of our advantage.

Likewise, the instructions to Japanese Embassies and Consulates to destroy their codes and coding machines were highly significant. Here again, Hawaii was not cut in directly. However, the commands in Hawaii were aware of it through their own surveillance of the Japanese Consulate as American representatives observed the burning of records there.

While we must recognize the possibility that the Pearl Harbor attack should have been blunted to some extent if more of the information avail able in Washington had been transmitted to Hawaii, there is room for other viewpoints. Harassed by the pressure of events and torrents of information, the responsible officials in Washington were subject to human limitations as to relative urgency, evaluation, and necessary action. Without doubt some officials, using their hindsight, could later see that certain things might have been done differently and better. At the time, however, it would seem that their estimate of the situation indicated that little could be gained by alerting Hawaii beyond what already had been done. As for the Hawaiian commands, some people observed that they were "fed up" on alarms, alerts, rumors, and an overdose of pressures and cautionary messages. Fleet operations were at times subordinate to alerts and defense drills, and suffered accordingly. The cry of "wolf" had become so customary that it no longer made an impact. And even if the Pacific Fleet had been fully ready, the damage would not have been much less. In fact, it might well have been much more.



1 Hearings, Part 12, p. 1.

2 Ibid., p. 7.

3 Ibid., p. 8.

4 Ibid., p. 10.

5 Ibid., p. 71.

6 Ibid., p. 165.

7 Ibid., pp. 192 and 193.

8 Ibid., pp. 204 and 205.

9 Ibid., p. 200.

10 Ibid., p. 206.

11 Ibid., p. 208 and 209.

12 Ibid., pp. 228 and 229.

13 Pacific Fleet Confidential Letter No. 2CL-41 (Revised), 14 October 1941, p. 1.

14 Ibid., Part 36, p. 442.

15 Report of the Joint Committee, p. 96.

16 Ibid., p. 98.

17 Ibid., p. 98.

18 Fortnightly Summary of Current National Situations, Navy Department, Serial No. 25, 1 December 1941, p. 9.

19 Report of the Joint Committee, p. 175.

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