(SC)A7 - 2(2)/FF1
Serial 067712
Secret-Memorandum                                         June 11, 1941.

From: The Director, War Plans Division.
To: The Director, Naval Districts Division
Subject: Air Defense of Pearl Harbor
Enclosure: (A) Com14 secret letter (0410) S-A16-3/A7-3(3) ND14 of May 1,
            1941, with enclosures.

1. Enclosure (A) should have been routed direct to the Director, Naval Districts Division for action.

2. It is recommended that copies of enclosure (A) be forwarded to all Commandants of Naval Districts, to the Commander in Chief, U. S. Atlantic Fleet, and the Commander in Chief, U. S. Asiatic Fleet, for use in the preparation of similar plans, and in the holding of joint exercises. It will be noted that copies have been furnished the Commander in Chief, U. S. Pacific Fleet.

                                                            R. K. TURNER.

                       OFFICE OF THE COMMANDANT

                       FOURTEENTH NAVAL DISTRICT
            AND NAvY YARD, PEARL HARBOR, HAWAII, u. s. A.

                                                             1 MAY 1941.
From: Commandant Fourteenth Naval District
To: Chief of Naval Operations.
Subject: Air Defense of Pearl Harbor
Reference: (a) Correspondence between the Secretaries of War and Navy on
           this subject dated 24 January 1941 and 7 February 1941.
   (A) Copies of two joint letters HHD-14ND dated 14 February 1941
   (B) Annex No. VII to the Joint Coastal Frontier Defense Plan (JCD-42)
   (C) Joint Estimate by Commander Hawaiian Air Force and Commander Naval
       Base Defense Air Force.

1. In connection with reference (a) there are enclosed herewith for your information copies of the principal directives issued in cooperation with the local

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Army authorities in accordance with which operation plans have been prepared, put into effect, and are in process of test and improvement, to provide for the joint defense of the Pearl Harbor Naval Base and ships of the Pacific Fleet in Hawaiian waters against surprise raids or air attacks.

2. Inclosure (A), two joint letters HHD-14ND dated 14 February 1941, initiated study by joint committees of Army and Navy officers of the joint problems of the defense which were mentioned in reference (a), and also included study of additional problems which were raised by the Commander-in-Chief, U. S. Pacific Fleet

3. Inclosure (B), Annex No. VII of the Joint Coastal Frontier Defense Plan, is a new joint agreement with the local Army authorities which pertains to joint security measures. Section II in particular relates to joint air operations.

4. Inclosure (C), Joint Estimate by Commander Hawaiian Air Force and Commander Naval Base Defense Air Force, serves as the basis of joint air operation orders which have been issued, placed in effect, and are in process of test, with a view to improvement in their effectiveness.

5. It is hereby certified that the originator considers it to be impracticable to phrase this document in such a manner as will permit a classification other than secret.

6. The urgency of delivery of this document is such that it will not reach the addressee in time by the next available officer courier. The originator therefore authorizes the transmission of this document by registered mail within the continental limits of the United States.

                                                             C. C. Bloch.
                                                             C. C. BLOCH.

Copy to:
   CinCPac (less inclosures)

C-A16-1/A6/A&N(3) (0137)
Headquarters Hawaiian Department,
Fort Shafter, T. H.

                                                     14th NAVAL DISTRICT,
                                                     PEARL HARBOR, T. H.,
                                                     14 FEBRUARY 1941.

Subject: Measures for Communication, coordination, and liaison between
         the Inshore Patrol and the Harbor Defenses.
To: Officers named in par. 2 herein.

1. Reference is directed to the following:

A. CGHD letter AG 354.2/24JAX of 11 January 1941.
B. General Gardiner's report on Joint Exercises of 7 November, 1940.
C. Chief of Naval Operations Serial 041230 of 5 November 1940.
D. Joint Coastal Frontier Defense Plan (Navy Short Title 14ND JCD-13-Army Short Title HC F-39), dated 14 April 1939.

2. In order to study and make recommendations to the Planning Representatives (Paragraph 4, Reference D) on measures for Communication, Coordination and Liaison between the Inshore Patrol and the Harbor Defenses, and to implement Reference C, the following joint Committee (Paragraph 6, Reference D) is appointed:

               Army Members:                Navy Members:
Fort DeRussy: Major I. N. Ritchie.  14ND Operations Officer: Comdr. H. B.
Fort Kamehameha: Major R. E. Binge-   Knowles.
   man.                             14ND C. O. Inshore Patrol: Comdr.
                                      G. B. Woolley

Enc. (A) Com14 serial (0410) 1 May 1941.

3. The studies and recommendations of the Committee will be based upon existing conditions and steps which may be taken in the near future to improve these conditions. Senior Officer of this Committee will act as its chairman. Direct consultation by committee members with any units under the control of the Department Commander or of the District Commandant is authorized and encouraged. The report containing the recommendations of the Committee will be submitted to the Planning Representatives (Paragraph 4, reference D) not later than 1 March 1941, with a view to the immediate establishment of a

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Harbor Control Post for Joint Defense of Pearl and Honolulu Harbors, as outlined in Chief of Naval Operations serial 041230 of 5 November 1940.

                                               WALTER C. SHORT
                                         Lieutenant General, U. S. Army
                                        Commanding, Hawaiian Department.
                                                C. C. BLOCH,
                                           Rear Admiral, U. S. N.

Copies to:
   Comdg. Gen. Haw. Dept.
   Comdg. Gen., ESCAB

   HEADQUARTERS                                          HEADQUARTERS
14th Naval DISTRICT                                   HAWAIIAN DEPARTMENT
PEARL HARBOR, T. H.                                   FORT SHAFTER, T. H.

                        NAVAL DISTRICT, 1939

                                                           28 MARCH 1941.



1. General

1. In order to coordinate Joint defensive measures for the security of the fleet and for the Pearl Harbor Naval Base for defense against hostile raids or air attacks delivered prior to a declaration of war and before a general mobilization for war, the following agreements, supplementary to the provisions of the HCF-39, (14 ND-JCD-13), are adopted. These agreements are to take effect at once and will remain effective until notice in writing by either party of their renouncement in whole or in part. Frequent revision of these agreements to incorporate lessons determined from joint exercises will probably be both desirable and necessary.

II. Joint Air Operations

2. When the Commanding General of the Hawaiian Department and the Naval Base Defense Officer, (the Commandant of the 14th Naval District), agree that the threat of a hostile raid or attack is sufficiently imminent to warrant such action, each commander will take such preliminary steps as are necessary to make available without delay to the other commander such proportion of the air forces at his disposal as the circumstances warrant in order that joint operations may be conducted in accordance with the following plans:

a. Joint air attacks upon hostile surface vessels will be executed under the tactical command of the Navy. The Department Commander will determine the Army bombardment strength to participate in each mission. With due consideration to the tactical situation existing, the number of bombardment airplanes released to Navy control will be the maximum practicable. This force will remain available to the Navy, for repeated attacks, if required, until completion of the mission, when it will revert to Army control.

b, Defensive air operations over and in the immediate vicinity of Oahu will be executed under the tactical command of the Army. The Naval Base Defense Officer will determine the Navy fighter strength to participate in these missions. With due consideration to the tactical situation existing, the number of fighter aircraft released to Army control will be the maximum practicable. This force will remain available to the Army for repeated patrols or combat or for maintenance of the required alert status until, due to a change in the tactical situation, it is withdrawn by the Naval Base Defense Officer (Commandant, 14th Naval District), and reverts to Navy control.

c. When naval forces are insufficient for long distance patrol and search operations, and Army aircraft are made available, these aircraft will be under the tactical control of the naval commander directing the search operations.

d. In the special instance in which Army pursuit protection is requested for the protection of friendly surface ships, the force assigned for this mission will pass to the tactical control of the Navy until completion of the mission.

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III. Joint Communications

* * * * * * *

5. Pending the establishment of the Aircraft Warning Service, The Army will operate an Antiaircraft Intelligence Service which, using wire and radio broadcasts, will disseminate information pertaining to the movements of friendly and hostile aircraft. It should be understood that the limitations of the AAAIS are such that the interval between receipt of a warning and the air attack will in most cases be very short. Radio broadcasts from the AAAIS will be transmitted on 900 kilocycles. All information of the presence or movements of hostile aircraft off-shore from Oahu which is secured through Navy channels will be transmitted promptly to the Command Post of the Provisional Antiaircraft Brigade.

6. Upon establishment of the Aircraft Warning Service, provision will be made for transmission of information on the location of distant hostile and friendly aircraft. Special wire or radio circuits will be made available for the use of Navy liaison officers, so that they may make their own evaluation of available information and transmit them to their respective organizations. Information relating to the presence or movements of hostile aircraft offshore from Oahu which is secured through Navy channels will be transmitted without delay to the Aircraft Warning Service Information Center.

7. The several joint communications systems listed in paragraphs 3 and 4 above, the Antiaircraft intelligence Service, and the Aircraft Warning Service (after establishment) will be manned and operated during combat, alert periods Joint exercises which involve these communications systems and at such other periods as may be agreed upon by the Commanding General Hawaiian Department and the Naval Base Defense Officer. The temporary loan of surplus communication equipment by one service to the other service to fill shortages in joint communication nets is encouraged where practicable. Prompt steps will be taken by the service receiving the borrowed equipment to obtain replacements for the borrowed articles through their own supply channels.

IV. Joint Antiaircraft Measures

8. Arrival and Departure Procedure, Aircraft.

During Joint exercises, alert periods and combat, and at such other times as the Commanding General Hawaiian Department and the Naval Base Defense Officer (Commandant Fourteenth Naval District) may agree upon, all Army and Navy aircraft approaching Oahu or leaving airfields or air bases thereon will conform to the Arrival and Departure Procedure prescribed in Inclosure A. This procedure will not be modified except when a departure therefrom is essential due to combat (real or simulated during exercises) or due to an emergency.

9. Balloon barrages.

Reports from abroad indicate the successful development and use of balloon barrages by European belligerents both British and German. Although detailed information is not available, the possibilities of balloon barrages in the Oahu area are recognized. Further investigation and study is necessary both locally and by the War and Navy Departments in order to determine the practicability of this phase of local defense.

10. Marine Corps Antiaircraft Artillery.

When made available by the Naval Base Defense Officer, (Commandant, 14th Naval District), Marine Corps units manning antiaircraft artillery present on Oahu will be placed under the tactical control of the Commanding General, Hawaiian Separate Coast Artillery Brigade.

11. Aircraft Warning Service.

The Army will expedite the installation and placing in operation of an Aircraft Warning Service. During the period prior to the completion of the AWS installations, the Navy, through use of RADAR and other appropriate means, will endeavor to give such warning of hostile attacks as may be practicable.

* * * * * * *

                                         (Signed) Walter C. Short,
                                                  WALTER C. SHORT,
                                          Lieutenant General U. S. Army,
                                         Commanding, Hawaiian Department.

Approved: 2 April 1941.
   (Signed) C. C. Bloch
            C. C. BLOCH,
   Rear Admiral, U. S. Navy,
Commandant Fourteenth Naval District.

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                                                          MARCH 31, 1941.

Comdr. Naval Base Defense Air Force,     Commanding General
Commander Patrol Wing TWO,               Hawaiian Air Force,
Naval Air Station,                       Fort Shafter, T. H.
Pearl Harbor, T. H.

Joint estimate covering Joint Army and Navy air action in the event of sudden hostile action against Oahu or Fleet Units in the Hawaiian area.

I. Summary of the Situation.

(a) Relations between the United States and Orange are strained, uncertain and varying.

(b) In the past Orange has never preceded hostile actions by a declaration of war.

(c) A successful, sudden raid, against our ships and Naval installations on Oahu might prevent effective offensive action by our forces in the Western Pacific for a long period.

(d) A strong part of our fleet is now constantly at sea in the operating areas organized to take prompt offensive action against any surface or submarine force which initiates hostile action.

(e) It appears possible that Orange submarines and/or an Orange fast raiding force might arrive in Hawaiian waters with no prior warning from our intelligence service.

II. Survey of opposing Strengths.

(a) Orange might send into this area one or more submarines and/or one or more fast raiding forces composed of carriers supported by fast cruisers. For such action she is known to have eight carriers, seven of which are reported to be capable of 25 knots or over and four of which are rated at 30 knots or better. Two of the carriers are converted capital ships, armoured and armed with 10-8" guns each and reported to have heavy AA batteries. Two others are small (7000 treaty tons) and limited to 25 knots. Exact information on numbers and characteristics of the aircraft carried by these ships is not available. However the best estimate at present available is that the small carriers can accommodate from 20 to 30 planes and the large ones about 60. Probably the best assumption is that carrier complements are normally about equally divided between fighter and bomber types. Lacking any information as to range and armament of planes we must assume that they are at least the equal of our similar types. There probably exist at least 12 eight inch gun and at least 12 six inch gun fast modern cruisers which would be suitable supports. Jane's Fighting Ships (1939) shows over forty submarines which are easily capable of projection into this area. An Orange surface raiding force would be far removed from their base and would almost surely be inferior in gun power to our surface forces operating at sea in the Hawaiian area.

(b) The most difficult situation for us to meet would be when several of the above elements were present and closely coordinated their actions. The shore-based air force available to us in a constantly varying quantity which is being periodically augmented by reinforcements from the mainland and which also varies as fleet units are shifted. Under existing conditions about one-half of the planes present can be maintained in a condition of material readiness for flight. The aircraft at present available in Hawaii are inadequate to maintain, for any extended period, from bases on Oahu, a patrol extensive enough to insure that an air attack from an Orange carrier cannot arrive over Oahu as a complete surprise. The projected outlying bases are not yet in condition to support sustained operations. Patrol planes are of particular value for long range scouting at sea and are the type now available in this area best suited for this work. If present planes are used to bomb well defended ship objectives the number available for future use will probably be seriously depleted. In view of the continuing need for long range overseas scouting in this area the missions of those planes for operations as contemplated in this estimate should be scouting. Certain aircraft of the Utility Wing although not designed for combatant work, can be used to advantage in augmenting the scouting of patrol planes. Other types of aircraft in general, can perform functions that accord with their type.

III. Possible enemy action.

(a) A declaration of war might be preceded by:

    1. A surprise submarine attack on-ships in the operating area.
    2. A surprise attack on OAHU including ships and installations in
       Pearl Harbor.
    3. A combination of these two.

(b) It appears that the most likely and dangerous form of attack on OAHU would be an air attack. It is believed that at present such an attack would

Page 536

most likely be launched from one or more carriers which would probably approach inside of three hundred miles.

(c) A single attack might or might not indicate the presence of more submarines or more planes awaiting to attack after defending aircraft have been drawn away by the original thrust.

(d) Any single submarine attack might indicate the presence of a considerable undiscovered surface force probably composed of fast ships accompanied by a carrier.

(e) In a dawn air attack there is a high probability that it could be delivered as a complete surprise in spite of any patrols we might be using and that it might find us in a condition of readiness under which pursuit would be slow to start, also it might be successful as a diversion to draw attention away from a second attacking force. The major disadvantage would be that we could have all day to find and attack the carrier. A dusk attack would have the advantage that the carrier could use the night for escape and might not be located the next day near enough for us to make a successful air attack. The disadvantage would be that it would spend the day of the attack approaching the islands and might be observed. Under the existing conditions this might not be a serious disadvantage for until an overt act has been committed we probably will take no offensive action and the only thing that would be lost would be complete surprise. Midday attacks have all the disadvantages and none of the advantages of the above. After hostilities have commenced, a night attack would offer certain advantages but as an initial crippling blow a dawn or dusk attack would probably be no more hazardous and would have a better chance for accomplishing a large success. Submarine attacks could be coordinated with any air attack.

IV. Action open to us:

(a) Run daily patrols as far as possible to seaward through 360 degrees to reduce the probabilities of surface or air surprise. This would be desirable but can only be effectively maintained with present personnel and material for a very short period and as a practicable measure cannot, therefore, be undertaken unless other intelligence indicates that a surface raid is probable within rather narrow time limits.

(b) In the event of any form of surprise attack either on ships in the operating areas or on the islands:

1. Immediate search of all sea areas within reach to determine the location of hostile surface craft and whether or not more than one group is present.

2. Immediate arming and preparation of the maximum possible bombing force and its dispatch for attack when information is available.

(c) In the event of an air attack on OAHU, in addition to (b) above:

1. The immediate dispatch of all aircraft suitable for aerial combat to intercept the attackers.

2. The prompt identification of the attackers as either carrier or long range shore based aircraft.

3. The prompt dispatch of fast aircraft to follow carrier type raiders back to their carriers.

(d) In the event of a submarine attack on ships in the operating area in addition to (b) above:

1. Hold pursuit and fighter aircraft in condition of immediate readiness to counter a possible air raid until search proves that none is imminent.

2. Dispatch armed shore based fleet aircraft to relieve planes in the air over the attack area.

3. Establish a station patrol by patrol planes two hundred twenty mile radius from scene of attack at one hour before daylight of next succeeding daylight period.

(e) None of the above actions can be initiated by our forces until an attack is known to be imminent or has occurred. On the other hand, when an attack develops time will probably be vital and our actions must start with a minimum of delay. It therefore appears that task forces should be organized now, missions assigned, conditions of readiness defined and detailed plans prepared so that coordinated immediate action can be taken promptly by all elements when one of the visualized emergencies arises. To provide most effectively for the necessary immediate action, the following joint task units will be required:

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1. Search Unit.

2. Attack Unit.

3. Air Combat Unit.

Carrier scouts, army reconnaissance and patrol planes can be employed with very widely varying effectiveness, either for search or attack. Under varying conditions some shifts of units between the search and attack groups may be desirable. Also, the accomplishment of these two tasks must be closely coordinated and therefore these two groups should be controlled by the same task group commander.

V. Decisions:

1. This force will locate and attack forces initiating hostile actions against OAHU or fleet units in order to prevent or minimize damage to our forces from a surprise attack and to obtain information upon which to base coordinated retaliatory measures

2. Subsidiary decisions. In order to be in all respects prepared to promptly execute the above decision:

(a) Establish a task organization as follows by the issue of a joint air operation plan:

1. Search and Attack Group (Commander Naval Base Defense Air Force (Commander Patrol Wing TWO)). The following units in accordance with current conditions of readiness:

 Patrol squadrons.
Shore-based VO-VS units.
Shore-based carrier VB and VT squadrons.
Shore-based carrier VS planes not assigned to the air combat group. Shore-based Marine VS and VB squadrons.
Army bombardment squadrons.
Army reconnaissance squadrons.
Navy Utility Squadrons.

2. Air Combat group (Commander Hawaiian Air Force) The following units in accordance with current conditions of readiness:

 Army pursuit squadrons.
Shore-based carrier VF squadrons.
Shore-based Marine VF squadrons.
One division of shore-based carrier VS planes. (Primarily for trailing aircraft).

(b) Assign missions to the above groups as follows:

1. Search and Attack Group. Locate, report and track all hostile surface units in position to take or threaten hostile action. Destroy hostile ships by air attack. Priority of targets: (1) carriers (2) large supporting ships. If choice of location is presented priority should be given to: (1) carrier involved in attack (2) vessels beyond reach of our surface vessel interception.

2. Air Combat Group. Intercept and destroy hostile aircraft. Identify and report type of attacking aircraft. Trail attacking carrier type planes to carrier and report location to commander search and attack group. As a secondary mission support search and attack group upon request.

(c) Provide a means for quickly starting all required action under this plan when:

    (a) An air attack occurs on OAHU.
    (b) Information is received from any source that indicates at attack
        is probable.
    (c) Information is received that an attack has been made on fleet

(d) Define conditions of readiness for use with this plan as follows:

Conditions of readiness shall be prescribed by a combination of a letter and number from the tables below. The letter indicating the part of a unit in a condition of material readiness for its assigned task and the number indicating the degree of readiness prescribed for that part.


A. All assigned operating aircraft available and ready for a task.

B. One-half of all aircraft of each functional type available and ready for a task.

C. Approximately one quarter of all aircraft of each functional type available and ready for a task.

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D. Approximately one-eighth of all aircraft of each functional type available and ready for a task.

E. All aircraft conducting routine operations, none ready for the purposes of this plan.


1. For pursuit and VF types-four minutes. Types other than fighters-fifteen minutes.

2 All types-30 minutes.

3 All types-one hour.

4. All types-two hours.

5. All types-four hours.

The armament and fuel load for each type under the above conditions of readiness are dependent upon the tasks assigned in contributory plans and orders and will be prescribed therein.

(e) Establish a procedure whereby the conditions of readiness to be maintained by each unit is at all times prescribed by the Senior officers present of the Army and Navy as a result of all information currently available to them. In using the above conditions it should be noted that: CONDITION A-1 requires a preparation period of reduced operations and can be maintained for only a short time as it is an all hands condition. CONDITIONS B-1 and B-2 require watch and watch for all personnel and personnel fitness for air action will decrease rapidly if they are maintained too long. Any condition 1, 2, or 3 will curtail essential expansion training work. CONDITIONS C, or D, 4 or 5 can be maintained without unduly curtailing normal training work.

V. Decisions:

(f) In order to perfect fundamental communications by use and to insure that prospective Task Group Commanders at all times know the forces immediately available to them for use, under the plan above, in case of a sudden emergency, provide, for daily dispatch readiness reports as of the end of normal daily flying from all units to their prospective task force commander. These reports to state:

(a) Number of planes in the unit by functional types such as bomber, fighter, etc.

(b) Number of each type in commission for flight and their degree of readiness as defined above.

(g) After the joint air operations plan under subsidiary decision (a) above has been issued, the task group commanders designated therein will prepare detailed contributory plans for their groups to cover the various probable situations requiring quick action in order that the desired immediate action in an emergency can be initiated with no further written orders. To assist in this work the following temporary details will be made:

(a) By Commander Naval Base Defense Air Force (Commander Patrol Wing TWO) an officer experienced in VF and VS operations and planning to assist the Commander of Air Combat Group.

(b) By the Commander Hawaiian Air Force: an officer experienced in Army bombardment and reconnaissance operations and planning to assist the Commander of the Search and Attack Group.

                                 (Signed) F. L. Martin,
                                          F. L. MARTIN
                                       Major General, U. S. Army,
                                    Commanding Hawaiian Air Force.

                                 (Signed) P. N. L. Bellinger,
                                          P. N. L. BELLINGER,
                                       Rear Admiral, U. S. Navy,
                                  Commander Naval Base Defense Air Force,
                                     (Commander Patrol Wing TWO).

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                        OFFICE OF THE COMMANDANT
                        FOURTEENTH NAVAL DISTRICT


Confidential                                               30 DEC. 1940.

From: Commandant, Fourteenth Naval District.
To: The Chief of Naval Operations
Via: Commander-in-Chief, United States Fleet.
Subject: Situation Concerning the Security of the Fleet and the Present
         Ability of the Local Defense Forces to Meet Surprise Attacks.
   (a) Opnav dispatch 092135 of October 1940.
   (b) Opnav dispatch 182128 of October 1940.
   (c) Chief of Naval Operations' personal letter addressed to CINCUS
       dated 22 November 1940 (copy sent to Com 14).
   (d) Com 14 dispatch 150055 of October 1940.
   (e) Com 14 dispatch 220230 of October 1940.

1. In view of the inquiries contained in references (a), (b) and (c), I consider it desirable to write this letter to set forth the present ability of the Fourteenth Naval District to meet surprise hostile attacks of an enemy with the equipment and forces at hand.


Aircraft attacking the base at Pearl Harbor will undoubtedly be brought by carriers. Therefore, there are two ways of repelling attack. First, by locating and destroying the carrier prior to launching planes. Second, by driving off attacking bombers with antiaircraft guns and fighters. The Navy component of the local defense forces has no planes for distant reconnaissance with which to locate enemy carriers and the only planes belonging to the local defense forces to attack carriers when located would be the Army bombers. The Army has in the Hawaiian area fifty-nine B-18 bombers. All of these are classified as being obsolete. The model is six years old and the planes themselves are five years old. Therefore, it is my opinion that neither numbers nor types are satisfactory for the purposes intended. New bombing planes are expected sometime in the future. However, not before July 1941. For distant reconnaissance, requisition would have to be made on the forces afloat for such as could be spared by the Fleet.

To drive off bombing planes after they have been launched will require both fighting planes and anti-aircraft guns. The Army has in the Hawaiian area thirty-six pursuit planes, all of which are classified as obsolete. Some of them are six years old and some of them are four years old. In numbers and models there is a serious deficiency existing. New fighters are expected when the P-40 is in production to the extent that the 185 projected for Hawaii can be delivered. This does not appear to be probable before the end of 1941; this number does not appear adequate.

The Army is charged with the protection of the Pearl Harbor base by antiaircraft guns. There are in Hawaii twenty-six fixed 3-inch guns and forty-four mobile 3-inch guns. There are projected twenty-four more, to be delivered in 1941. There are no 37-millimeter and only 109 .50 caliber out of the projected 120 37-millimeter and 308 .50 caliber machine guns. The Army plans to place the greater part of the 3-inch guns around Pearl Harbor and only a few near other military objectives. In my opinion, it will be necessary to increase the numbers of guns around Pearl Harbor greatly to have any semblance of antiaircraft defense. Furthermore, I express my doubt as to the efficacy of a 3-inch gun with a 21-second fuse for driving off high altitude bombers. The Army has made no plans for the anti-aircraft defense of Lualualei or Kaneohe, furthermore, it will be necessary to have a considerable concentration of anti-aircraft guns to defend the shipping terminals and harbor of Honolulu in order that lines of communication may be kept open. With a limited knowledge of the density of anti-aircraft barrages abroad, I am of the opinion that at least 500 guns of adequate size and range will be required for the efficient defense of the Hawaiian area. This number is in addition to 37-millimeter and .50 caliber machine guns.

In addition to the above, the Army has planned an aircraft warning service which will consist of eight Radar stations. Three of these stations are fixed and five are mobile. When completed at an indefinite time in the future, this warning net should be adequate.

Page 540


The ideal defense against submarines would be conducted by patrol vessels and aircraft working in conjunction. The district has no aircraft for this purpose. Recently, there have arrived here three vessels of Destroyer Division EIGhTy which is assigned to the local defense forces. These vessels have listening gear and, when repaired and ready for service, will be a valuable contribution for antisubmarine and escort work. A large number of patrol vessels will be required for anti-submarine work in the vicinity of Oahu and the other islands. At present, the district has none and request would have to be made on the Fleet for such vessels and planes as could be spared for this most important work. No anti-submarine nets are planned, nor are any considered desirable. Anti-torpedo nets are projected for the entrances of Honolulu and Pearl Harbor. They will probably be delivered about 1 March 1941. The net depot will be completed somewhat later.


The district has recently built and equipped one sweep barge and three tugs are being equipped for towing and energizing the coil. This barge can probably look out for Honolulu and Pearl Harbor until such time as it is seriously injured. The district has no vessels available for use as sweeps for anchored mines. A number of mine sweepers are being built or purchased, but their delivery dates here are uncertain. A large number of sweepers will be required in order to keep the harbors of Pearl Harbor, Honolulu and Kaneohe clear and, in addition, Hilo on Hawaii, Kahului and Lahaina on Maui, and Port Allen and Nawiliwili on Kauai. With the delivery of sweepers now being built or purchased, the general situation will be improved immeasurably.


The coast defenses of the Army are considered adequate except that Kaneohe receives very little protection from the batteries.


There are two tank farms, the upper and the lower. The lower is entirely contained in the government reservation and, by the use of roving patrols, is considered reasonably secure. The upper farm is adjacent to a public highway. The farm is surrounded by an unclimbable fence and each tank with an earth berm. Its chief exposure is along the highway. To counteract this, three elevated sentry stations have been erected, each equipped with searchlights. This enables sentries to keep a continuous lookout over the entire fence line day and night, the upper farm is considered fairly secure.


Recently, a guard house has been erected and an arrangement has been made, the Marines alternating with the Army, for constant guard on the water supply.

A constant guard is kept on the electric supply lines through which outside power is received.

8. An elaborate system of photographic passes, search and examination is in effect. There are over 5,000 Civil Service employees who come into the yard each day. In addition, there are about 5,000 employees of civilian contractors and several thousand enlisted men. In addition to the above, there is a constant stream of trucks and vehicles of all descriptions carrying supplies, stores, et cetera. It is impossible to maintain absolute security without disruption of the work of the yard. However, surprise searches and periodic stops, et cetera, are in effect in order that the alert may be emphasized. The main gate has been strengthened to prevent rushing; there have been two drills for the purpose of giving surprise training to the yard garrison in the event of a surprise riot in the yard. In addition to the above, a survey has been made not only of the yard but of all of the outlying stations, and every effort is being made to close holes and stop gaps. While the Commandant is not satiated, he feels that the precautions taken are reasonably effective but that they are susceptible to improvement, which will be made as occasion warrants.

9. It should be borne in mind that until comparatively recently none of us in this country had very much conception of what measures were necessary and what provisions were desirable in order to effect any measure of protection against aircraft, against submarines, against mines and against subversive elements. The officers and men of this command have been alert, zealous and vigilant in executing all measures under their control in order to properly prepare the district for any exigencies.

10. It should be assumed that the War Department is fully aware of the situation here and that they are proceeding vigorously with a view to overcoming deficiencies. It may be that they have failed to recognize the necessity for large

Page 541

numbers of anti-aircraft guns and pursuit planes. I suggest that the Chief of Naval Operations make inquiry from the War Department as to what their plans are and on what dates they predict that they will be accomplished and then, if the numbers and dates are not satisfactory, these features may be discussed at length.

11. It is considered highly undesirable from my point of view that the War Department should in any way come to believe that there is lack of agreement between the Army authorities and Navy authorities here, or that the officials of the Fourteenth Naval District are pressing the Navy Department to do something in regard to Army matters.

                                                             C. C. Bloch.
                                                             C. C. BLocH.
CinC File No.

                                             UNITED STATES FLEET
                                         U. S. S. NEW MEXICO, Flagship,
                                       Pearl Harbor, T. H., Jan. 7, 1941.

First Endorsement to
Com 14 Conf. Ltr.
(629) of 30 Dec. 1940.

From: Commander-in-Chief, United States Fleet.
To: The Chief of Naval Operations.
Subject: Situation Concerning the Security of the Fleet and the Present
         Ability of the Local Defense Forces to Meet Surprise Attacks.

1. Forwarded. The Commander-in-Chief has conferred with the Commandant Fourteenth Naval District and the Commanding General of the Hawaiian Department. As a result of the conference with the Commanding General, Hawaiian Department, and an inspection in company with him, information was furnished the Commandant Fourteenth Naval District who prepared the basic letter. The Commander-in-Chief concurs with the Commandant Fourteenth Naval District who prepared the basic letter. The Commander-in-Chief concurs with the Commandant Fourteenth Naval District in the opinion that the present Army Pursuit Squadrons and antiaircraft batteries are inadequate to protect the Fleet and Pearl Harbor against air attack. When established the proposed pursuit strength will be adequate. The proposed total of 68 mobile three-inch guns for this area is not considered adequate. With the almost continuous high ceiling prevailing in this area a materially greater number of larger and longer range antiaircraft guns are necessary to counter high altitude bombing attacks on Pearl Harbor.

2. As neither the increased antiaircraft batteries nor the augmented pursuit squadrons will be available for an extended period the defense of Fleet units within Pearl Harbor will have to be augmented by that portion of the Fleet which may be in Pearl Harbor in event of attack by hostile aircraft. Plans for co-operation with the local defense forces are being made. At present the continuous readiness of carrier fighter squadrons or antiaircraft batteries is not contemplated. The improbability of such an attack under present conditions does not, in the opinion of the Commander-in-Chief, warrant interrupting entirely the training required by Fleet air units which would have to be largely curtailed if constant readiness of a fighter squadron were required.

3. There does not appear to be any practicable way of placing torpedo baffles or nets within the harbor to protect the ships moored therein against torpedo plane attack without greatly limiting the activities within the harbor, particularly the movements of large ships and the landing and take-off of patrol squadrons. Inasmuch as Pearl Harbor is the only operating base available to the Fleet in this area any passive defense measures that will further restrict the use of the base as such should be avoided. Considering this and the improbability of such an attack under present conditions and the unlikelihood of an enemy being able to advance carriers sufficiently near in wartime in the face of active Fleet operations, it is not considered necessary to lay such nets.

4. The defense against submarines and mines are considered adequate under present peace time conditions, but early installation of underwater sound submarine detection system should be made. Also the delivery of the required ships to the Fourteenth Naval District Defense Forces should be expedited, particularly ships for sweeping magnetic and anchored mines.

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5. In this connection, it is urgently recommended that Local Defense Forces, adequate for the protection of naval installations at Pearl Harbor and the Fleet units based thereon, be provided the Commandant Fourteenth Naval District. In order to provide freedom of action for the United States Fleet, and further, to avoid the necessity for detailing important Fleet units (because no other ships are available) to tasks requiring only part of their full capabilities, it is considered that the forces provided should be sufficient for full protection and should be independent of the presence or absence of ships of the U. S. Fleet. It is further considered that the provision of adequate Local Defense Forces for the Fourteenth Naval District should be given higher priority than continental Naval Districts, where both the possibilities of, and objectives for, attack are much less.

                                                        J. O. Richardson.
                                                        J. O. RICHARDson.

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