REPORT OF NAVY COURT OF INQUIRY
 Under date of 13 July, 1944. this Court of Inquiry was ordered by the Secretary of the Navy to inquire into all circumstances connected with the attack made by the Japanese armed forces on Pearl Harbor, Territory of Hawaii, on 7 December, 1941, to include in its findings a full statement of facts deemed to be established, to give its opinion as to whether any offenses have been committed or serious blame incurred on the part of any person or persons in the naval service and, in case its opinion be that offenses have been committed or serious blame incurred, to specifically recommend what further proceedings should be had.
The Court convened on 24 July, 1944, and since then has held daily sessions almost continuously in Washington, San Francisco, and Pearl Harbor, having called and examined numerous witnesses from the State, War, and Navy Departments.
The Court, having thoroughly inquired into all facts and circumstances in connection with the attack by the Japanese armed forces on Pearl Harbor on 7 December, 1941, and having considered all evidence adduced, finds as follows:
FINDINGS OF FACTS
Pearl Harbor is situated on the Island of Oahu, near the city of Honolulu, the capital of the Territory of Hawaii, distant 2100 miles from San Francisco. It is the only permanent outlying United States Naval Base in the Eastern Pacific. It possesses great strategic importance as a point from which naval operations in defense of the Western United States can be conducted, and offensive operations against an enemy to the Westward launched and supported. The United States possesses no base on the West Coast of the United States that meets these requirements to an equivalent extent.
Prior to 1940 certain subdivisions of the Pacific Fleet and, beginning in May, 1940, the entire Fleet operated in the  Hawaiian area with Pearl Harbor as a base. In May, 1941, three battleships, one aircraft carrier, four cruisers, and nine destroyers were detached from the Pacific Fleet and transferred to the Atlantic.
For the purpose of conducting exercises and maneuvers at sea designed to increase efficiency and readiness for war, the remaining major vessels of the Pacific Fleet were organized in three main Task Forces. The operating schedule was so arranged that there was always at least one of these Task Forces, and usually two, at sea. Frequently, during Fleet maneuvers, the entire available Fleet was at sea.
The vessels and the Fleet planes thus rotated their scheduled periods in port, periods essential to the mobility of the Fleet for purposes impossible of achievement at sea. At no time during 1941 were all the vessels of the Fleet in Pearl Harbor.
The operating schedule in effect on 7 December, 1941, was issued in September, 1941. In accordance with its provisions Task Force One, under the command of Vice Admiral W. S. Pye, U. S. N., and part of Task Force Two were in Pearl Harbor at the time of the attack. Task Force Three, under the command of Vice Admiral Wilson Brown, U. S. N., was at sea, engaged chiefly in escorting the aircraft carrier LEXINGTON to Midway to which point planes were being ferried.
Part of Task Force Two, under the command of Vice Admiral W. F. Halsey, Jr., U. S. N., and including the aircraft carrier ENTERPRISE, was returning from ferrying planes to Wake.
 Task Force One included the preponderance of the battleship strength of the Fleet. The three battleships of Task Force Two had been left behind in Pearl Harbor because their slow speed did not permit them to accompany the ENTERPRISE to Wake. It was purely a coincidence that all battleships of the Pacific Fleet, except one undergoing overhaul at the Puget Sound Navy Yard, were in Pearl Harbor on 7 December.
Beginning at 0755, Honolulu time, on 7 December, 1941, an attack was delivered from the northward of Oahu by Japanese carrier aircraft against units of the United States Pacific Fleet then moored and anchored inside the Pearl Harbor Naval Base, against Army and Navy aircraft, and against shore installations on the Island of Oahu. An attack delivered simultaneously by Japanese midget submarines was without effect. The details of these attacks and the extent of the loss of life and of the damage inflicted by Japanese aircraft have since been made matters of public record.
Within the same 24 hours the Japanese also delivered attacks on the Philippines, Wake and Guam, as well as on Hong Kong and Malaya. The attack on Pearl Harbor cannot be disassociated from these. All were the reprehensible acts of a warrior nation, war- minded and geared to war through having been engaged in hostilities for the past four years, and long known to have aggressive designs for the dominance of the Far East. The United States was then at peace with all nations and for more than 20 years had not engaged in  hostilities.
In time of peace it is a difficult and complicated matter for the United States to prevent an attack by another nation because of the constitutional requirement that, prior to a declaration of war by the Congress, no blow may be struck until after a hostile attack has been delivered. This is a military consideration which gives to a dishonorable potential enemy the advantage of the initiative, deprive the United States of an opportunity to employ the offensive as a means of defense, and places great additional responsibility on the shoulders of commanders afloat in situations where instant action, or its absence, may entail momentous consequences.
From 1 August, 1939, to 25 March, 1942, the Chief of Naval Operations, charged by law under the Secretary of the Navy with the operations of the Fleet and with the preparation and readiness of plans for its use in war, was Admiral Harold R. Stark, U. S. N. The Commander-in-Chief of th Pacific Fleet from 1 February to 17 December, 1941, was Admiral Husband E. Kimmel, U. S. N. The Commanding General of the Hawaiian Department from 7 February to 17 December, 1941, was Lieut. General Walter C. Short, U. S. A. The Commandant of the 14th Naval District from 11 April, 1940, until 1 April, 1942, was Rear Admiral Claude C. Bloch, U. S. N. He was an immediate subordinate of Admiral Kimmel and was charged by him with the task of assisting the Army in  protecting Pearl Harbor. With respect to those duties connected with the defense of Pearl Harbor, Rear Admiral Bloch's responsibility was solely to Admiral Kimmel. It is an established fact that this responsibility was discharged to the complete satisfaction of the latter.
Admiral Kimmel and Lieut. General Short were personal friends. They met frequently, both socially and officially. Their relations were cordial and cooperative in every respect and, in general, this was true as regards their subordinates. They frequently conferred with each other on official matters of common interest, and invariably did so when messages were received by either which had any bearing, on the development of the United States-Japanese situation, or on their several plans in preparing for war. Each was mindful of his own responsibility and of the responsibilities vested in the other. Each was informed of measures being undertaken by the other in the defense of the Base to a degree sufficient for all useful purposes.
For some time preceding the attack on Pearl Harbor, the United States, engaged in the protection of shipping and the patrolling of sea lanes in the Atlantic, was passing through the preliminary stage of a transition from a state of national military unpreparedness to an ability to cope successfully with two resourceful and fully prepared enemies. The vigorous and convincing representations made by Admiral  Stark before Congressional committees, beginning in January, 1940, showed clearly that the Navy was unprepared for war and greatly needed ships, planes, and men. These representation, linked with the fall of France, resulted in an Act of Congress in June, 1940, whereby appropriations were voted for practically doubling the size of our Navy.
During all of 1941 and for some time thereafter the problem confronting both the Chief of Naval Operations and the Chief of Staff. U. S. Army, was one of expansion and of distributing, to the best advantage, the limited supply of ships, planes, guns, and men and intensifying the training of personnel while production was being stepped up.
Under date of 30 December, 1940, Rear Admiral Bloch, Commanding the 14th Naval District and the Navy Yard, Pearl Harbor, after conference with Admiral Richardson, the then Commander-in-Chief, Pacific Fleet, and Lieut. General Herron, the then Commanding General Hawaiian Department, initiated correspondence addressed to the Chief of Naval Operations in which he set forth the inability of the 14th Naval District to meet a hostile attack with the equipment and forces at hand. He pointed out that, as Naval Base Defense Officer, he had no planes for distant reconnaissance. He gave as his opinion that neither in numbers nor types were the Army bombers satisfactory for the purpose intended. He invited attention to the serious deficiency on the part of the Army with regard to both fighting planes and anti-aircraft guns. He noted also that an anti-aircraft warning system planned  by the Army was scheduled for completion at an indefinite time in the future.
This letter was forwarded to the Navy Department by Admiral Richardson, by endorsement. He concurred in the opinion that the Army aircraft and anti-aircraft batteries were inadequate to protect the Fleet in Pearl Harbor against air attack, and urged that adequate local defense forces be provided. He further expressed the opinion that the forces provided should be sufficient for full protection, and should be independent of the presence or absence of ships of the Fleet.
Under date of 24 January, 1941, the Secretary of the Navy addressed a letter to the Secretary of War, based upon the representations made by the Commandant of the 14th Naval District and the recommendations of the Commander-in-Chief, Pacific Fleet, and in general concurrence herewith. In this letter the belief was expressed that, in case of war with Japan hostilities might be initiated by a surprise attack upon the Fleet or on the naval base at Pearl Harbor. The dangers envisaged in the order of their importance and probability were considered to be: (1) Air bombing attack. (2) Air torpedo plane attack. (3) Sabotage. (4) Submarine attack (5) Mining (6) bombardment by gunfire.
Defense against all but (1) and (2) being considered satisfactory, it was proposed that the Army assign the highest priority to the increase of pursuit aircraft and anti-aircraft artillery, and the establishment of an air warning net in Hawaii; also that the Army give consideration  to the questions of balloon barrages. The employment of smoke, and other special devices for improving the defenses at Pearl Harbor; that local joint plans be drawn for defense against surprise aircraft raids; that there be agreement on appropriate defences of joint readiness for immediate action against a surprise aircraft raid; and that joint exercises for defense against surprise aircraft raids be held.
The Secretary of War, under date of 7 February, 1941, expressed complete concurrence as to the importance of the subject and the urgency of making every possible preparation to meet such a hostile effort. He pointed out that the Hawaiian Department was the best equipped of all overseas Army departments and held a high priority for completion of its projected defenses because of the importance of giving full protection to the Fleet. He outlined the details of the Hawaiian project and stated the number of pursuit planes and antiaircraft guns eventually to be supplied. He stated that the equipment for the aircraft warning system was expected to be delivered in
Hawaii in June, 1941, and that all arrangements for installation would have been made by the time the equipment was delivered.
Copies of these letters were furnished Admiral Kimmel, Lieut. General Short, and Rear Admiral Bloch.
In a letter dated 17 October, 1941, Rear Admiral Bloch reported to the Chief of Naval Operations that the only increment that had been made to the local defense forces during the past year, exclusive of net vessels, was the U.S.S. SACRAMENTO, an old gunboat of negligible gun power  and low speed. He urged that the Department send a number of small fast craft equipped with listening gear and depth charges for anti-submarine purposes and further urged that he be sent two squadrons of VSO planes to be used for patrol against enemy submarines.
Admiral Kimmel forwarded this letter with the following endorsement:
"There is a possibility that the reluctance or inability of the Department to furnish the Commandant, 14th Naval District, with forces adequate to his needs may be predicated upon a conception that, in an emergency, vessels of the U.S. Pacific Fleet may always be diverted for these purposes. If such be the case, the premise is so false as to hardly warrant refutation. A fleet tied to its base by diversions to other purposes of light forces necessary for its security at sea is, in a real sense, no fleet at all. Moreover, this Fleet has been assigned, in the event of war, certain definite tasks, the vigorous prosecution of which requires not only all the units now assigned but as many more as can possibly be made available. The necessities of the case clearly warrant extraordinary measures in meeting the Commandant's needs."
The Chief of Naval Operations replied, under date of 25 November, 1941, that no additional vessels could be supplied for the present but that certain sub chasers, due for completion in May, 1942, had been tentatively assigned to the 14th Naval District, certain privately owned vessels might be expected at a future time and that there were no additional airplanes available for assignment to the 14th Naval District.
It is a fact that, through 1941, the demand for munitions and war supplies exceeded the capacity of the nation and in all important commands there existed marged [sic]  deficiencies in trained personnel and in material equipment and instruments of war. Although shortages were inevitable, it is a further fact that they had direct bearing upon the effectiveness of the defense of Pearl Harbor.
On 5 November, 1941, the Chief of Naval Operations and the Chief of Staff, U. S. Army, submitted a joint memorandum to the President, recommending that no ultimatum be delivered to Japan at that time and giving, as one of the basic reasons the existing numerical superiority of the Japanese Fleet over the U. S. Pacific Fleet.
On 7 December, 1941, the U. S. Pacific Fleet was numerically inferior to the Japanese naval forces in both combatant and auxiliary vessels.
Aware of this existing weakness in relative fighting strength, and of the vigorous steps being taken by the United States to overcome deficiencies, Japan clearly sensed the advantage of striking before these steps could become effective. Her advantageous position was strength-
ened by her extensive espionage system which utilized her civilian, consular and diplomatic nationals throughout the world, and enabled her constantly to keep accurately informed of the U. S. Naval building program and of the location and movements of U.S. Naval vessels.
The topography of Oahu is peculiarly suited to the observation of Pearl Harbor and its activities. The local officials of the United States were unable to overcome Japan's advantage in this respect. It was impossible for  them to prevent anyone from obtaining military information and, because of legal restrictions imposed by the Federal statutes, they could not interfere with the mails and the transmission of messages by radio, telegram, and cable.
In addition, having in mind Japan's traditional tendency to distort legitimate actions of a peaceful nation into deliberate threats to her own security and prestige, the War and Navy Departments were compelled to take every precaution to avoid offending her super- sensitive sensibilities. For example, as of 16 October, 1941, the Chief of Naval Operations directed the Commander-in-Chief, Pacific Fleet, to "take such preparatory deployments as will not constitute provocative action against Japan" and, on 28 November, 1941, the War Department directed the Commanding General of the Hawaiian Department to "undertake no offensive action until Japan has committed an overt act".
In contrast to the ease with which Japanese in United States territory, particularly in Hawaii, were able to obtain and to transmit to Japan military information of value, every obstacle was placed in the way of such information being collected in Japan by foreign nationals.
As an instance of Japanese secretiveness and surveillance of foreigners, including those of the U. S. Diplomatic services, the U. S. Naval attache in Tokyo was compelled to report to the Japanese Navy Department whenever he contemplated an excursion beyond the limits of the city, and he was closely watched at all times. He was effectively prevented from obtaining any information as to the type and  number of Japanese ships under construction and the capacity of their naval shore establishments, as well as of the location and movements of Japanese ships.
It is a fact that the superiority of the Japanese Fleet and the ability of Japan to obtain military and naval information gave her an initial advantage not attainable by the United States up to 7 December, 1941.
A naval base exists solely for the support of the Fleet. The fundamental requirement that the strategic freedom of action of the Fleet must be assured demands that the defense of a permanent naval base be so effectively provided for and conducted as to remove any anxiety of the Fleet in regard to the security of the base, or for that of the vessels within its limits. Periodical visits to a base are necessarily made by mobile seagoing forces in order that logistics support may be provided and opportunity given for repair and replenishment, for rest and recreation, and for release of the personnel from a state of tension.
To superimpose upon these essentials the further requirements that the seagoing personnel shall have the additional responsibility for se-
curity from hostile action while within the limits of a permanent naval base, is to challenge a fundamental concept of naval warfare. There is not, and there has not been, any lack of understanding on the part of the Army and Navy on this point. The defense of a permanent naval base is the direct responsi-  bility of the Army. The Navy is expected to assist with the means provided the naval district within whose limits the permanent naval base is located and the defense of the base is a joint operation only to that extent. To be adequate, the defense must function effectively during the periods when the Commander- in-Chief and all the units of the Fleet are absent.
In the case of naval districts lying beyond the continental limits of the United States, the commandant of the district occupies a dual status. As commandant of the district, he is governed by all existing instructions relating to the duties of commandants of naval districts and is answerable direct to the Navy Department. He is also an officer of the Fleet and as such is under the Commander-in- Chief of the Fleet for such duties as the latter may designate.
The fact that the Commandant of the 14th Naval District was thus designated as an officer of the Pacific Fleet is the circumstance that links the Commander-in-Chief, Pacific Fleet, with the duty of assisting the Army in defending the permanent naval base of Pearl Harbor. Except for this, the chief responsibility of the Commander-in-Chief, Pacific Fleet, was for the readiness, the efficiency, and the security of the vessels of the Fleet while at sea. It is through gaining and maintaining control of vital sea areas that a Fleet contributes to the defense of the shore and its activities.
The defense of the permanent naval base of Pearl Harbor was the direct responsibility of the Army.
Under date of 27 February, 1941, the Commandant, 14th Naval District, Rear Admiral Bloch, in his capacity as Naval Base Defense Officer, issued an operations plan establishing security measures, including air defense and surface ship patrol, in order to cooperate with and assist the Army in protecting Pearl Harbor and safeguarding the Fleet.
Under date of 28 March, 1941, joint agreements were reached between Lieut. General Short and Rear Admiral Bloch, as to joint security measures for the protection of the Fleet and the Pearl Harbor Base. It was agreed that when the threat of a hostile raid or attack was considered sufficiently imminent to warrant such action, each commander was to take such preliminary steps as were necessary to make available without delay to the other commander such portion of the air forces at his disposal as the circumstances warranted.
Joint air attacks upon hostile *surface* vessels were to be executed under the tactical command of the Navy. The Army bombardment strength to participate in each such mission was to be determined by the commander, Hawaiian Department, the number of bombardment planes released to Navy control to be the maximum practicable.
Defensive *air operations* over and in the immediate vicinity of Oahu were to be executed under the tactical command of the Army. The
Commandant, 14th Naval District, was to determine the Navy fighter strength to participate  in these missions, the number of fighter aircraft released to Army control to be the maximum practicable.
When naval aircraft under the command of the Naval Base Defense Officer were insufficient for long-distance patrol and search operations, and Army aircraft were made available, the Army aircraft so made available were to be under the tactical control of the Naval commander directing the search operations.
The Naval Base Defense Officer was entirely without aircraft, either fighters or patrol planes, assigned permanently to him. He was compelled to rely upon Fleet aircraft for joint effort in conjunction with Army air units. The Commander Patrol Wing Two, Rear Admiral P. N. L. Bellinger, U. S. N., was by Admiral Kimmel placed under Rear Admiral Bloch's orders, and was by the latter directed to consult with the Army and to prepare a detailed naval participation air defense plan. Rear Admiral Bellinger thus was given the additional status of the Commander Naval Base Defense Air Force, while retaining his status as an air officer of the Fleet.
Under date of 31 March, 1941, plans were drawn up and jointly agreed upon by Rear Admiral Bellinger and Major General F. L. Martin, U. S. Army, Commanding Hawaiian Air Force. These plans were complete, and their concept was sound. Their basic defect lay in the fact that the naval participation depended entirely upon the availability of aircraft belonging to the Fleet. This circumstance was forced by necessity, but was at complete variance with the fundamental requirement that to be adequate, the defense of  a permanent naval base must be independent of assistance from the Fleet.
The effectiveness of these plans depended entirely upon advance knowledge that an attack was to be expected within narrow limits of time and the plans were drawn with this as a premise. It was not possible for the Commander-in-Chief of the Fleet to make Fleet planes permanently available to the Naval Base Defense Officer, because of his own lack of planes, pilots, and crews and because of the demands of the Fleet in connection with Fleet operations at sea.
Shortly after assuming command of the Pacific Fleet, Admiral Kimmel issued specific comprehensive instructions as to the steps to be taken for the security of the Fleet in the operating sea areas. Aware of the inadequacy of the shore defenses of Pearl Harbor, he also required the vessels, while at the base, to assist to the limit of their resources. These instructions were revised and brought to date on 14 October, 1941 were given wide circulation within the Pacific Fleet, and were sent for information to other commands and to the Navy Department.
The security of the Pacific Fleet, operating in the Hawaiian Area and based on Pearl Harbor, was predicted on two assumptions:
(a) That no responsible foreign power will provoke war, under present existing conditions, by attack on the Fleet or Base, but that irresponsible and misguided nationals of such powers may attempt;
 (1) sabotage, on ships based in Pearl Harbor, from small craft.
(2) to block the entrance to Pearl Harbor by sinking an obstruction in the Channel.
(3) To lay magnetic or other mines in the approaches to Pearl Harbor.
(b) 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 operating area,
(3) a combination of these two.
The measures prescribed to provide against these possibilities included continuous inshore, boom, and harbor patrols, intermittent patrol of the inner and offshore areas by destroyers, daily search of operating areas by air, the covering of sortie and entry, and daily sweeps for magnetic and anchored mines. The only entrance to Pearl Harbor was guarded by an anti-torpedo net.
The Task Forces operating at sea were screened protectively by aircraft and destroyers. Torpedo defense batteries were manned day and night, ammunition was at hand, and depth charges were ready for use. Water-tight integrity was maintained, horizon and surface battle lookouts were kept posted, the ships steamed darkened at night, and the use of the radio was restricted to a minimum.
Admiral Kimmel, recognizing the potentialities of the submarine as an instrument of stealthy attack, and believing that Japanese submarines were operating in Hawaiian waters, was of the opinion that this form of surprise attack against his Fleet was the one most likely to be employed by Japan. Therefore, he had issued, on his own responsibility, orders that all unidentified submarines discovered in Hawaiian waters  were to be depth-charged and sunk. In so doing he exceeded his orders from higher authority and ran the risk of committing an overt act against Japan, but did so feeling that it is best to follow the rule "shoot first and explain afterwards".
Actually, in execution of these orders, a midget submarine was discovered in an operating area, attacked and destroyed by the combined efforts of a naval patrol plane and a destroyer of the inshore patrol, about 20 minutes prior to the air attack on the morning of 7 December. There was nothing, however, in the presence of a single submarine in the vicinity of Oahu to indicate that an air attack on Pearl Harbor was imminent.
It is a fact that the precautions taken by Admiral Kimmel for the security of his Fleet while at sea were adequate and effective. No naval units were either surprised or damaged while operating at sea in the Pacific prior to or on 7 December, 1941.
While vessels of the United States Navy are lying in port, it is the invariable custom to keep on board a number of officers and men sufficient to provide for internal security, and to protect against fire and the entrance of water. The force so remaining on board is always balanced as to ranks and ratings so that all requirements can be met in case of emergency. A watch is maintained day and night.
In other than normal situations a "condition of readiness" is placed in effect. On the morning of 7 December considerably  more than half of the Naval personnel were on board their ships in Pearl Harbor, more than ample to meet an emergency in port. Their
efficiency and their heroic behavior on that day are proof of their fitness for duty.
The Navy's practice in numbering its three prescribed "conditions of readiness" is opposite to the method adopted by the Hawaiian Department of the Army in numbering its "alerts". With the Army, the No. 3 alert represents the maximum state of readiness, while the Navy refers to that state as No. 1. In the interest of clarification, definition of the respective states of readiness is here set forth:
Army Alerts / Navy Conditions of Readiness
No. 1. Defense against sabotage and uprisings. No threat from without. / No. 1. Entire crew, officers and men at battle stations. Action imminent.
No. 2. Security against attacks from hostile sub-surface, and aircraft, in addition to No. 1. / No. 2. Provides the means of opening fire immediately with one-half the armament. Enemy believed to be in vicinity.
No. 3. Requires occupation of all field positions./ No. 3. Provides a means of opening fire with a portion of the secondary and antiaircraft batteries in case of surprise encounter.
The alert in effect in the Hawaiian Department of the Army at the time of the attack was their No. 1. The condition of readiness of the vessels in Pearl Harbor at that time was an augmented Navy No. 3. This condition had been in effect for many months preceding that date. To assume  a high condition of readiness in port and to man guns and stations which cannot be utilized in any circumstance, is to impose on the entire personnel an unjustified state of tension and to defeat the purpose for which the vessels have entered the base; i. e., to make repairs, to replenish supplies, to give the personnel rest and relaxation, and thus to prepare for operations at sea.
The same holds true with regard to the patrol planes of the Fleet. And to a small number of fighters that had been left behind by the absent carriers. They were part of the Fleet, engaged in daily operations and, when not operating, were undergoing overhaul or the crews were being rested in anticipation of further operations. At the time of and immediately prior to the attack on the morning of 7 December 1941, some were in the air covering the movement of a task force, others were on 30 minutes notice, some others were on 4 hours notice, and the remainder were under overhaul.
These planes were not part of the permanent defense of Pearl Harbor. To have kept the crews awake and ready with engines warmed up, in the absence of any indication of an impending attack, would have been to undermine their further usefulness.
The Navy controlled none of the guns mounted on shore. The only means available to the vessels of the Fleet for contributing to their own defense against aircraft while in Pearl Harbor was their anti-aircraft batteries. The anti-aircraft batteries installed on the ships in Pearl Harbor were incapable of a volume of fire at all comparable to that of the batteries of the same ships today.
 On all ships inside Pearl Harbor a considerable proportion of the anti-aircraft guns was kept manned day and night and with ammunition immediately at hand. Also, by prearrangement with the Army, there was in effect a system, correct as to its details, for the coordinating of the anti-aircraft fire of vessels of the Fleet in part with that of the Army on shore.
Existing Fleet orders provided for the establishment of air defense sectors within the Pearl Harbor area, and for the berthing of ships within the Harbor in such positions as to develop the maximum anti- aircraft gun fire in each sector, commensurate with the total number of ships of all types in port.
These orders were carried out to the letter. On the morning of the attack the vessels of the Fleet brought hostile planes, as they came within one or more of these air defense sectors, under heavy fire intensified within a very few moments by the full fire of the entire anti-aircraft batteries of all ships.
It is a fact that the Navy's condition of readiness in effect on the morning of 7 December, 1941, was that best suited to the circumstances then attending the vessels and patrol planes of the Pacific Fleet. A higher condition of readiness could have added little, if anything to their defense.
An attack by carrier aircraft can be prevented only by intercepting and destroying the carrier prior to the launch-  ing of planes. Once launched, the attacking planes can be prevented from inflicting damage only by other planes or anti-aircraft gunfire or both. Even when a determined air attack is intercepted, engaged by aircraft, and opposed by gunfire, some of the attacking planes rarely fail to get through and inflict damage.
To destroy an aircraft carrier before she can launch her planes requires that her location be known and that sufficient force, in the form of surface or underwater craft, or aircraft, or all three, be at hand. To have the necessary force at or near the point of intended launching in time to insure the destruction of the carrier, it is necessary that the carrier's presence in a general area, and within narrow limits of time, be known or predicted with reasonable accuracy. Even in time of war the fulfillment of this condition is difficult where vast sea areas are involved, and where both the point from which the carrier departs, as well as the fact of her departure, are unknown.
This was the case during the days immediately prior to 7 December 1941. Japanese carriers sailed at an unknown time from an unknown port. Their departure and whereabouts were a closely guarded Japanese secret and were likewise unknown, all rumors to the contrary notwithstanding.
Although the U.S. Ambassador to Japan reported, as of 27 January, 1941, that there was a rumor to the effect that a surprise attack on Pearl Harbor was planned, its authenticity was discounted in the Embassy for the reason that such an attack, if actually contemplated, would scarcely be likely to be a topic of conversation in Japan.
 The Navy Department informed the Commander-in-Chief, Pacific Fleet, of this rumor and stated that the Navy Department "places no credence in these rumors. Furthermore, based on known data regarding the present disposition and employment of Japanese naval and army forces, no move against Pearl Harbor appears imminent or planned for in the foreseeable future".
In time of war, an outlying naval base may be expected to become an enemy objective, sooner or later. It is an established fact, however, that no information of any sort was, at any time, either forwarded
or received from any source which would indicate that carriers or other ships were on their way to Hawaii during November or December, 1941.
The attack of 7 December, 1941, on Pearl Harbor, delivered under the circumstances then existing, was unpreventable. When it would take place was unpredictable.
Where a carrier's presence in a general area is not known in advance and is not predictable within narrow limits of time, there must be resort to procedure which will give warning of a hostile approach. The usual procedure employed by carriers bent on delivering a surprise attack, although by no means the only procedure possible, is to arrive about 700 miles from the objective at dark the night preceding the attack, steam at high speed during the night, and launch the planes at dawn, about 400 miles from the objective. It  is this general procedure which establishes early morning as the time when an air attack is most likely to be delivered. The events of 7 December, 1941, point to the likelihood of this procedure having been followed by the Japanese.
The greatest degree of warning of an impending early morning air attack is obtained if the hostile carrier be sighted prior to dark the night before. In such event, a maximum warning of about twelve hours may be obtained. In the case of an island base, such as Pearl Harbor, it is necessary to cover the circumference of a circle of 700 miles radius each day (the direction from which the attack is expected being unknown) in order to obtain either positive or negative information.
Assuming 25 miles visability (which in the Hawaiian area is not found everywhere nor always assured), an effective daily search requires the daily employment of patrol planes which, in turn, requires that double or triple that number (180-270) be available, it being impossible to employ the same planes and crews every day, or even every other day.
If only the dawn circle of 400 mile radius is to be searched daily, the total number of planes required to be available is 100-150. The maximum warning; is then reduced to about two hours.
Where planes are not available to cover all sectors, the selection of sectors to be omitted is left purely to chance and under such circumstances the advisability of the diversion of all planes from other duties is questionable unless there be information as to the fact of a hostile  approach and of the direction, within reasonable limits, from which the approach is expected.
Neither surface ships nor submarines properly may be employed to perform this duty, even if the necessary number is available. The resulting dispersion of strength not only renders the Fleet incapable of performing its proper function, but exposes the units to destruction in detail. A defensive deployment of surface ships and submarine over an extensive sea area as a means of continuously guarding against a possible attack from an unknown quarter and at an unknown time, is not sound military procedure either in peace or in war.
It was the duty of Rear Admiral Bloch, when and if ordered by the Commander-in-Chief, Pacific Fleet, to conduct long-range reconnaissance. The Commander-in-Chief, Pacific Fleet, for definite and sound reasons and after making provision for such reconnaissance in case of
emergency, specifically ordered that no routine long-range reconnaissance be undertaken and assumed full responsibility for this action. The omission of this reconnaissance was not due to oversight or neglect. It was the result of a military decision, reached after much deliberation and consultation with experienced officers, and after weighing the information at hand and all the factors involved.
In brief, the deciding factors were:
(a) The Naval Base Defense Officer, Rear Admiral Bloch, although charged with the conduct of the reconnaissance, had no patrol planes permanently assigned to his command.
 (b) The only Naval patrol planes in the Hawaiian area were the 69 planes of Patrol Wing Two and these were handicapped by shortages of relief pilots and crews. They were a part of the Fleet, and not a part of the permanent defense of Pearl Harbor. The only other planes suitable and available for daily long range reconnaissance were six Army bombers.
(c) The task assigned the Commander-in-Chief, Pacific Fleet, was to prepare his Fleet for war. War was known to be imminent (how imminent he did not know). The Fleet planes were being constantly employed in patrolling the operating areas in which the Fleet's preparations for war were being carried on. Diversion of these planes for reconnaissance or other purposes was not justified under existing circumstances and in the light of available information.
(d) If so diverted, the state of readiness of the Fleet for war would be reduced because of the enforced suspension of Fleet operations.
(e) The value of the Fleet patrol planes to the Fleet would be reduced seriously after a few days because of the inability of planes and crews to stand up under the demands of long-range reconnaissance.
It is a fact that the use of Fleet patrol planes for daily long-range, all-around reconnaissance was not justified  in the absence of information indicating that an attack was to be expected within narrow limits of time. It is a further fact that, even if justified, this was not possible with the inadequate number of Fleet planes available.
At the time of the attack, only a few vessels of the Pacific Fleet were fitted with radar. The radar of vessels berthed in a harbor such as Pearl Harbor, partially surrounded by high land, is of limited usefulness at best and does not provide the necessary warning of a hostile approach.
The shore-based radar on the Island of Oahu was an Army service and entirely under Army control. The original project called for 6 permanent (fixed) and 6 mobile installations. The fixed installations had not been completed by 7 December, 1941, and only 3 sets had been shipped to Oahu up to that time. On that day there were in operation 6 mobile sets located in selected positions, with equipment in efficient condition, but inadequately manned.
Training of personnel had started on 1 November, 1941. Lieut. General Short earlier had requested that the Navy assist in this training,