JAPANESE MONOGRAPH No. 92

Southwest Area Naval Operations

Apr. 1942 - Apr. 1944

(Supplementary maps appended to the end of this digital version.)

Through Instruction No. 126 to Japanese Government, 12 Oct 45, entitled "Institution for War Records Investigation", steps were initiated to exploit military historical records and official reports of the Japanese War Ministry and the Japanese General staff.* Upon the dissolution of the War Ministry and the General staff, and the transfer of their former functions to the Demobilization Bureau, the general research job continued and resulted in the development of a series of historical monographs. Detailed instructions covering the preparation of these monographs were included in Memoranda 15 December 1945 and 21 November 1946, subject "Japanese Operational histories",

The basic material contained in this operational record was developed by former officers, on duty in command and staff units within major units during the period of operations. It should be noted at once, that the enormous destruction by aerial bombardment and fire has practically wiped out the Tokyo records; much of this material was reconstructed from memory.

The paucity of original orders, plans and unit journals, which are normally essential in the preparation of this type of record, most of which were lost or destroyed during field operations or bombing raids rendered the task of compilation most difficult; particularly distressing has been the complete lack of official strength reports, normal in AG or G-3 records. However, while many of the important orders, plans and estimates have been reconstructed from memory and therefore are not textually identical with the originals, they are believed to be generally accurate and reliable. Further data as a result of continuing research and the occasional recovery of hitherto unavailable original documents will be covered in the subsequent publication of "supplements" by the Demobilization Bureau.

*The action under this memorandum and incidental detailed instructions, which followed, were initiated by the Assistant Chief of Staff, G-2, GHQ, charges with responsibility for execution of the program under G.O. No. 9, SCAP, 2 October 1945.

In order to protect the interest of the United States, in the exploitation of Japanese Military Information, sub-paragraph 4 of G.O. No. 9 further provided for the screening of enemy documents and established inventories in Japanese Governmental Archives. Careful examination of the first records submitted by the Japanese Government in the summer of 1946 detected a misconception on the part of the Japanese as to what should be included in comparative histories; in a memorandum issued by Assistant Chief of Staff, G-2, on 21 November 1946, the Imperial Japanese Government was directed to record the operations of the Japanese forces more extensively. The G-2 Section thereafter assumed coordination of the entire program, including the establishment of a small historical research section within the ATIS (Allied Translator and Interpreter Section.)

GENERAL HEADQUARTERS

SUPREME COMMANDER FOR THE ALLIED POWERS

MILITARY INTELLIGENCE SECTION, GENERAL STAFF ALLIED TRANSLATOR AND INTERPRETER SECTION

Translation Requested by Historical Section

Received ATIS: 10 Sep 47

Description of Contents: Full translation of booklet entitled

Operations in the Southwest Area

(TN * indicates an exact ROMAJI transliteration of the original KANA.)

Operations In the Southwest Area

(From April 1942 to April 1944)

(Note) This chapter covers the second stage of the operation, from about April 1942 to the beginning of February 1943. However, in the southwest area, even after the above period, that is during the third stage of operations, the same situation prevailed as in the second stage of the operation. Since it seems best to summarise the operations in the Southwest area to cover the above periods instead of dividing them chronologically, this chapter will cover the operation as a whole, that is, from April 1942 to April 1944.

Generally speaking, the operations in the Southwest area during this period consisted of the converting of natural resources in the southern area for war use and operational preparations for the defense of strategic points in the Southwest area. It is necessary to discuss the former in order to judge the general course of the war. However, this requires a clarification of the conversion of resources in the southern area and their shipment to JAPAN. The Japanese Navy kept insufficient statistical data, so, unfortunately, it is impossible to arrange such details at the present time.

The Japanese Army was in primary control during the period of preparations for defensive operations, while the Navy merely took charge of escorting and transportation. Data is lacking regarding this also. Consequently, the following is merely one conception of the activities of the Navy within the foregoing period.

In compiling this account, fragments of operation records and war service records now extant were used as references and the opinions of survivors concerned were sought, as much as possible. Therefore, we do not consider

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ourselves responsible for many insufficient or unsatisfactory details in the account.

I. Summary from the Occupation of JAVA to the Issuance of the Order for the Second Stage of the Operation

In early March 1942, the Japanese forces completed the occupation of the main Island of JAVA, Immediately, Japanese forces continued to advance and to carry out their campaign of conquest northward, to SUMATRA, the ANDAMANS, BURMA, and western NEW GUINEA, as mentioned previously. To freshen the memory and to clarify the transition to the second stage of the operation, a general summary of the situation follows, regardless of possible repetition.

About the middle of March 1942 in the Burma area, the 15th Army, which had advanced by land from the Thailand Area, penetrated RANGOON, and the main island of JAVA also capitulated. Further, on 12 March the units under the 25 Army, which was engaged in the invasion of MALAYA, landed on KOETA RADJA in Northern SUMATRA, escorted by the Navy. At dawn on 23 March, our Army and Navy units landed on ANDAMAN and immediately occupied this area. Just about this time, the first Army transport-convoy for the invasion of BURMA arrived in RANGOON from SINGAPORE, at dawn on 24 March. After that, transports arrived in RANGOON continually and carried out the attacks immediately. These military units occupied LASHIO, located near the border of BURMA and CHINA, on 29 April, MANDALAY, the important point, on 1 May, and BAHMO, YUNNAN, LUNLIAO and AKYAB in succession.

In conjunction with the landing operation in the Andaman and Burma areas, operations in the Indian Ocean area were carried out with the greater part of the task forces

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and the Southern Expeditionary Fleets participating. (The details of this operation were fully described in the "Task force" section.) This operation advanced from KENDARI through the lines of the Sunda Islands, in order to co-operate with the aerial attacks on the Ceylon area by the task force, which was mobilized in the Indian Ocean. Thus, the operation of the Bay of BENGAL was carried out by the Southern Expeditionary Fleet. The results were successful, as expected. With the completion of this campaign, the operations in the southern areas, carried out by the main squadron, came to an end for the time being. Although the punitive campaign for the PHILIPPINES and Western NEW GUINEA (these were described in the sixth paragraph of the foregoing chapter, "Invasion of Northern SUMATRA and Punitive Campaigns of Various Areas in the Southwestern Area") had not been completed, on 10 Apr 42 the order was issued for the distribution of the strength of the combined Fleet for the second stage of the operation. Through this order, the Commander-in-chief of the Second Fleet, who had been in charge of directing southern operations in general, was released, and, at the same time, the main points of Japanese naval strength, which had been placed in the southern area, were now transferred to the Eastern front.

II. Issue of Order for the Disposition of Strength of the Combined Fleet for the Second Stage of the Operation

As mentioned above, orders for the disposition of strength for the second stage of the operation were issued on 10 Apr 42. The details of the disposition were as follows:

(Table)

Disposition of Strength for the Second Stage of the Operation

(After the Conclusion of the Operation in the Southern Areas)

Force

Commander

Strength

Main Duties

Main Force

The
Commander-
in-
chief of
the
Combined Fleet

1st Battleship Division let Fleet (less 3rd and 6th Squadrons)

To support the whole campaign

Advanced Force

Commander of the 2nd Fleet

2nd Fleet 5rd Battalion 4th Carrier Division

To support the operation of the Northern, South Sea, and Southern Forces

Carrier Base Air Force

Commander of the 1st Air Fleet

1st Air Fleet (less 4th Carrier Division)

To destroy enemy task forces

Reconnaissance Unit

Commander of the 6th Fleet

6th Fleet

Continuance of First Operation

Base Air Force

Commander of the 11th Air Fleet

11th Air Fleet (less pert of the force) 26th Special Naval Landing Force

Patrol of the necessary zones and fighting em the base

Southern Force

Southwest Area Fleet Commander

1st, 2nd, 3rd Southern Expeditionary Fleet 4th, 6th Submarine Squadron 3 Patrol boats AKASHI ASAHI MARU and MUROTO

56th Special Naval Landing Force

ASAHI, one section of the 11th Air Fleet

(1) Mopping up operation in the occupied area;

Check enemy invasions;

Stabilize Defense of strategic points

(2) Destroy enemy sea routes along the Northwest coast of AUSTRALIA and Indian Ocean Area

(3) Attack enemy air base in northern AUSTRALIA if situation requires

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Force

Commander

Strength

Main Duties

Southern Force

Chief of the 4th Fleet

4th Fleet

6th Cruiser Division

11th Carrier Division

One section of the 1st Combined Communication Force

(1) Strengthen patrol and defense of the South Seas; Secure and defend strategic points of occupied area

(2) Capture strategic points of BISMARCK and British NEW GUINEA

Northern Forces

Chief of the 5th Fleet

5th Fleet

CHICHIJIMA Communication

(KISARAZU Air Squadron depot)

(1) Strengthen patrol and defense of the northern waters

(2) Look-out and attack strategic points in the ALEUTIANS

(S) Guard against RUSSIA

Commerce Raider Unit

Commander of the 24th Squadron

24th Squadron

Same as the First Operation

Communication Force

Commander of the 1st Combined Communication Force

1st Communication Force (less one part)

Attached Force

CHIYODA

SETTSU

YAKAZE

(Remarks: The disposition of vessels for replacements is stated in a separate paragraph.)

Prior to this, with the conclusion of the operations in the PHILIPPINES, the 3rd Southern Expeditionary Fleet mas newly organised, on 3 Jan 42, to take charge of defense duties for this area. At the same time, the former Southern Expeditionary Fleet became the 1st Southern Expeditionary Fleet. Furthermore, on 10 March, the 3rd Fleet was reorganised as the

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2nd Southern Expeditionary Fleet. These reorganizations were made to meet the necessity of the approaching period of defense. On 10 April, the wartime organization of the Imperial Navy was revised and the former 1st, 2nd, and 3rd Southern Expeditionary Fleets were put under the unified command of the Southwest Area Fleet, which was newly organized in the Southwest area. However, the Commander-in-chief of the 2nd Southern Expeditionary Fleet held an additional post as Commander-in-chief of the Southwest area Fleet. The Emperor appointed Vice Admiral TAKAHASHI, Koremochi as Commander-in-chief of the. Southwest area Fleet, The following is the main strength under the command of the Southwest area Fleet at that time:

1st Southern Expeditionary Fleet

9th Special Base Force (PENANG)

10th " (SINGAPORE)

11th " (SAIGON)

12th " (RANGOON)

2nd Southern Expeditionary Fleet

ASHIGARA

16th Squadron (NATORI, KINU, ISUZU) 21st Special Base Force (SURABAYA) 22nd " (BALIK PAPAN)

23rd "(MACASSAR)

24th " (AMBOINA)

3rd Southern Expeditionary Fleet

31st Special Base Force (MANILA)

32nd " (DAVAO)

1st Sea Escort Squadron

In addition to the revision of the wartime organization of the Japanese Navy, dated 10 April, the new Southwest area

Fleet commander was to take charge of operations in the southern area, aided by the 21st and 23rd Air Squadron, by the order for the disposition of the strength of Combined Fleet for the second operation, issued on the above-mentioned date. His main duties were as stated in the disposition of strength of the combined Fleet for the second operation.

III. Division of Guard Duties and Execution of Military Administration

Since the method of allotting defense duties for the Southern occupation area between the Army and Navy is directly connected with the execution of military administration in that area and, furthermore, is connected with the future development of natural resources there, various negotiations were carried out by Army and Navy officials. As a result, an agreement was reached at the beginning of 1942 and the Imperial Headquarters Navy Staff Section issued instructions. After that, the basic policy of allotting the defense areas generally remained the same. However, minor details changed, according to the tactical situation. Following is a general outline of the change.

The agreement of the Army and Navy central authorities regarding the defense of the PHILIPPINES, British MALAYA, and the DUTCH EAST INDIES was indicated in the instructions of the Grand Imperial Headquarters Navy Staff Section No. 38 and No. 43, issued, respectively, on 3 and 20 Jan 42.

Instruction No. 38 of the Grand Imperial Headquarters Navy Staff Section

Agreement of the central authorities of the Army and Navy regarding defense of the PHILIPPINES

1. In the defense of the PHILIPPINES, the Navy will be in charge of sea defense, naval installation areas, and air bases already in its care. All others will be controlled

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by the Army.

2. The defense of naval installation areas will be based upon the agreement of the central authorities of the Army and Navy concerning the execution of military administration of occupation zones. The agreement of the central authorities on naval bases, military sea transport bases, and ship and harbor service is described in a separate document.

3. Air bases under Navy control are designated in the first supplementary paragraph of the central authorities' Army and Navy aerial agreement for the southern operation.

Instruction No. 43 of the Same.

Agreement of the Army and Navy Central Authorities on the defense of British MALAYA and the Dutch EAST INDIES.

1. The Navy will take charge of sea defense, naval installation areas and air bases already in its care in British MALAYA, BORNEO, JAVA, and SUMATRA. All others will be controlled by the Army.

2. Regarding the defense of the DUTCH INDIES (except JAVA and SUMATRA), the Army will take charge of areas where Army units are stationed, and other areas will be controlled by the Navy. The boundary lines of areas where Army units are to be stationed will be designated through agreements by local Army and Navy commanders.

3. The defense of naval installation are as will be based upon the agreement by central authorities of the Army and Navy on the execution of military administration in occupation zones, which is included in separate paragraphs.

The agreement of central authorities on naval bases, military sea transportation bases, and ships and harbor services will be executed as determined in separate documents No. 2 and No. 3.

4 The air bases in charge of the Navy will be executed

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as determined in additional paragraph No. 1 of the aerial agreement by the Army and Navy central authorities for the Southern Operation.

Instruction No. 109 of Grand Imperial Headquarters Navy Staff Section, "Agreement of the Central Army and Navy Authorities Concerning the Defense of Strategic Points in the Southern Area" was issued on 27 Jun 42. The contents of these instructions cannot be clarified at present, because of the lack of data. It seems, however, that it is similar to the revised central agreement of January 1943, which will be discussed below. The central agreements were prepared for changes in the administration of TIMOR (Instruction of the Grand Imperial Headquarters Navy Staff Section No. 122) on 21 Aug 42, and also for strengthening the defense of the Lesser Sunda Islands, the Aru Islands and the Tenimber Islands on 15 Oct 42.

Instruction No. 122 of Grand Imperial Headquarters Navy Staff Section.

Revised Portion of the Army and Navy Central Agreements on the Defense of Strategic Points in the Southern Area.

1. "Lesser Sunda Islands" in the first paragraph of the defense disposition discussed in Part 6 will be changed to "Lesser Sunda Islands." (excluding Timor Island)

2. The sixth paragraph of the same will, be changed as follows: "Direct defense of TIMOR will be primarily in charge of the Army. However, the Army will concentrate its strength as much as possible, besides taking direct charge of the defense of strategic points. The Navy will take charge of air defense, and, at the same time, it will support the defense of the Army. Details will be settled through agreements by local Army and Navy commanders."

Grand Imperial Headquarters Navy Staff Section Instruction No. 146.

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Agreement of Amy and Navy Central Authorities

1. Regarding the Strengthening of Defenses of the Lesser Sunda Islands, TANIMBAR, and the Aru Islands.

1. Object of Operation

It is the object of this operation to strengthen the defenses of Sunda Islands, TANIMBAR, and the Aru Islands, through the reinforcement of defensive strength.

2. Troops to be Employed: A part of the Southern Army

3. Summary of Operation: The Army will land on the above-mentioned islands escorted by the Navy, and will strengthen the defense.

4. Defense and Control:

a. In accordance with the Agreement of Army and Navy Central Authorities No. 6 on the allotment of defense among strategic Southern points, the Army will chiefly take charge of the direct defense of the Lesser Sunda Islands, the Tanimbar Islands, and the Aru Islands. The Navy will chiefly take charge of air defenses. However, until the "RE" operation is generally concluded, air defense will be under the co-operative command of both the Army and the Navy.

b. Regarding land defense, the supreme commander of naval land combat units in the above-mentioned islands will be under the command of the army supreme commanders. However, if the rank of the naval commander is higher, the army commander will be under the command of the naval commander in regard to the land defense.

5. Other matters: The Navy will support the Army as much as possible in regard to supply and sanitation.

6. The Commander-in-chief of the Southern Army and the commander-in-chief of the Southwest Area Fleet will make agreements regarding minor details.

On 13 Jan 43, the agreement of Army and Navy central

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authorities regarding the defense of the Southern Strategic Area (revised) was drawn up. After that, no revisions were made in this agreement until the termination of the war.

Grand Imperial Headquarters Navy Staff Section Instruction No. 189.

Agreement of the Army and Navy Central Authorities Regarding the Defense of the Southern Strategic Area. (revised) (Notes)

1. The Southern Strategic Area mentioned in this Agreement includes the occupied southern region, which lies to the west of Dutch NEW GUINEA, including Dutch NEW GUINEA, THAILAND, and INDO-CHINA.

2. This Agreement is a revision of "The agreement of the Army and Navy Central Authorities regarding the defense of strategic points in the southern area", issued on 29 Jun 42, to cope with the situation at that time.

General Provisions

1. This agreement prescribes the regulations to be enforced, besides the following Agreements of the Army and Navy Central Authorities on the defense of strategic points in the Southern Area, and local agreements based upon this central agreement:

The Agreement of the Army and Navy central authorities regarding the execution of military administration for occupied areas.

The Agreement of the Army and Navy central authorities regarding the defense of the PHILIPPINES.

(Supplementary to the preceding agreement)

The Agreement of the Army and Navy central authorities regarding the defense of British MALAYA and the Dutch East Indies area.

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The Central Agreement regarding the Army sea transport bases, Naval bases, and shipping and harbor service.

Defense Policy

2. The Army and Navy will co-operate in offensive operations which will be carried out with ships, small craft and air forces to destroy the enemy plans for counterattack.

3. The defense of strategic points will be strengthened promptly. In case of an enemy attack the Army and Navy will closely co-operate and will take the initiative in destroying the enemy.

4. Surface transportation between JAPAN and strategic points in the southern area will be safeguarded.

Outline of Defense

5. Defense Allotment: The surface defense of occupied areas will be carried out by the Navy. As a basic rule, the direct defense of the Andaman Islands, Nicobar Islands, Christmas Island, Southern BORNEO, and the CELEBES will be primarily carried out by the Navy. The land defenses of other islands will be carried out by the Army. However, the Army and Navy will co-operate in carrying out the defense if the operation requires it.

Offensive Operations

6. a. The Navy will neutralize the surface frontiers of occupied areas and will take charge of search and precautions against the enemy. Concurrently, the Navy will carry out timely attacks with aircraft and submarines against AUSTRALIA and Indian Ocean areas. Also, to meet the enemy situation, ships and small craft will advance to destroy enemy ships.

b. The Army will mainly destroy the enemy air forces in Southwest CHINA and Northeast INDIA, as well as other strategic points. If necessary, the Army will support

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the attack against enemy ships in the vicinity.

Direct Defense

7. a. The emphasis of direct defense will be placed on the main air bases, harbors, and oil refineries, which are threatened by enemy attack, and on possible enemy landing points.

b. The Army will always co-operate with the Navy

in the direct defense of the Andaman Islands. If necessary, the Army will dispatch troops to other islands which are placed under Navy authority for defense purposes. However, the Navy will also co-operate with the Army in the defense of strategic points affiliated with the Navy which are included in the areas assigned to the Army, or will take complete charge of defense.

c. In order to check the invasion of enemy submarines, the Navy will block or dominate the straits, as necessary from the viewpoint of defense. However, if a blockade of the above-mentioned straits Is to be carried out in a section assigned to the Army, It will be necessary to consult With the Army commander in the area concerned.

d. The Navy will take charge of main surface defense activities in the southern strategic area.

e. If it is necessary for the execution of the two preceding articles, the Navy will consult with the local Army commander regarding the disposition of defense equipment at necessary points which are in areas assigned to the Army, and the necessary personnel will be stationed as necessary.

Protection of Surface Traffic

8. a. The Navy will check the invasion of enemy submarines in the South Sea region and, at the same time, will strengthen the mopping-up operations against these submarines.

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b. The Navy will be in charge of protecting surface traffic in the South Seas and between JAPAN and the southern strategic area. The Army will co-operate with the Navy. Details concerning Army transport escort are contained in the agreement between the Army and Navy commanders concerned.

Aerial Navigation

9. In regard to aerial navigation, refer to the separate document, "The Agreement of Army and Navy Central Authorities Regarding Aerial Navigations."

Chain of Command

10. In case Army and Navy forces are stationed in the same area, the supreme commander of the Naval landing force will be under the command of the supreme commander of the Army as far as land defense is concerned. If, however, the Navy commander is of higher rank, the Army commander will be under the command of the Navy commander with regard to land defense.

Agreement of Army and Navy Commanders

11. The following commanders will promptly conclude an agreement regarding land defense, based on this agreement: The commander in chief of the Southern Army and the commander of the Combined Fleet and the commander of the Southwestern Area Fleet; the 14th Army commander, the commander of the 3rd Southern Expeditionary Fleet and the commander of the Southwestern Area Fleet.

Mutual Communication and Others

12. The Army and Navy will maintain close liaison in matters concerning disposition of essential units for defense and other necessary matters.

13. Any important information, especially that which is valuable for judging enemy plans of counterattacks or harassing actions, will be reported immediately by the Army

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or Navy commanders concerned.

14. Hereafter, the former Dutch NEW GUINEA will be called the WEST NEW GUINEA, and the former British NEW GUINEA will be called EAST NEW GUINEA.

At the outbreak of war the following agreement was concluded between the Army and Navy staff sections of Grand Imperial Headquarters concerning assignment of areas for the execution of military administration in occupied areas:

Areas chiefly assigned to the Army (assisted by the Navy): HONGKONG, PHILIPPINES, British MALAYA, SUMATRA, JAVA, British BORNEO and BURMA.

Areas assigned chiefly to the Navy (assisted by the Army): Dutch BORNEO, the CELEBES, the Moluccas Islands, Lesser Sunda Islands, NEW GUINEA, the Bismarck Islands and GUAM.

The following outline of the military administration was decided at a conference between Grand Imperial Headquarters and the Government:

a. The Object of Military Administration: Restoration of the public peace.

Prompt acquisition of important material for national defense.

Maintenance of self-sustenance of local operational troops.

b. Basic Point of Military Administration:

(1) In executing the military administration, existing governmental organizations will be used as much as possible and former traditions and racial customs must be respected.

(2) The occupation forces will provide means for promoting the acquisition and development of important materials for national defense, so far as it will not interrupt the operational plan.

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(3) As a principle, acquisition of important resources for national defense and sustenance of local occupation forces should not exert a bad influence upon the people. Harmony between the demands for the promotion of good will among people and the above principles must be taken into consideration.

(4) Treatment of American, British and Dutch nationals will be carried out so as to co-operate with the military administration, but measures will be taken to deal with those who do not co-operate.

(5) The rights and property of Axis nationals will be respected, but further extension of rights and property will be limited as much as possible.

(6) Chinese nationals will be guided so as to separate them from the Chiang Kai-shek government and to have them co-operate with our policy.

(7) The natives will be guided so as to promote their trust in the Japanese Army.

(8) The Japanese who want to enter this area for the first time after the opening of the operation will be chosen with care. The re-entrance of those who lived in this area previously will receive priority.

The execution of military administration was as follows: With the end of the Southern operation, the civil administration department was gradually established in its important points, in order to take direct charge of civil administration by conforming with the operation regarding prompt restoration of the public peace, which was destroyed after the war, and with the aim of co-operating with the operation. The Civil Administration Departments were first established in BALIKPAPAN, MACASSAR, and AMBOINA. These departments received orders from commanders of local special base units and executed civil administration accordingly.

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In May 1942, the Civil Government and Civil Administration Department of the Southwestern Area Fleet was organized. The general director of Civil Administration of the Southwestern Area Fleet was ordered by the Fleet Commander to execute civil administration in the area under the control of the Fleet. These key personnel for the administration arrived in the early part of July 1942, and established a Civil Administration Government and a Celebes Civil Administration Department in MACASSAR, a Borneo Civil Administration Department in BANJERMASIN, and a Ceram Civil Administration Department in AMBOINA. Branches were established in various important districts for the execution of civil administration.

The Operation from April 1942 to the beginning of Autumn of the same year.

Among the main operations carried out during this period, occupational operations in BURMA and WESTERN NEW GUINEA, the Indian Ocean operation, and the Christmas Island occupational operation have been described previously. In addition to these, there were the air operation against the northwest coast of AUSTRALIA and the operation for the destruction of enemy communications in the Indian Ocean area, involving the submarine squadron and the 24th squadron (the HOKOKU-MARU and AIKOKU-MARU). Since the latter battle will be described in the paragraph dealing with the submarine operation It will not be mentioned here. The air operation against the northwestern coast of AUSTRALIA will be discussed here.

After the occupation of JAVA and the Andaman Islands, the Japanese Naval air force, which completely dominated the western sector, directed its power to the northwestern coast of AUSTRALIA and the Indian Ocean. Ninety-six land attack planes and about 24 seaplanes of the 21st Air Regiment

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attacked the western area from the ANDAMANs. There were about 96 fighters and 48 land attack planes attached to the 23rd Air Regiment in northern AUSTRALIA. After the revision of the Japanese Navy's wartime organization, the above-named forces continued their duties with their allotted strength.

On 22 March, and on 5, 6, 25 and 27 April, the air forces, under the 23rd Air Regiment, attacked primarily the Port Darwin area with fighters and bombers. At the end of April, a concentration of enemy planes in the Port Darwin area was spotted. After 22 May, enemy planes attacked the Amboina and Kupan* areas. On 14 and 15 June, the 23rd Air Regiment carried out a great daylight attack on PORT DARWIN and 51 enemy planes were shot down (the fate of 14 of these planes is unknown). However, reinforced Allied air power in the Port Darwin area was quite active. At the end of June, the Amboina, Timor, and Kendari* areas were attacked by enemy planes.

Prior to this, on 1 May, the 21st Air Regiment, which was under the southwestern area fleet commander, was reorganized into the Southwestern Area Fleet through the revision of the Imperial Navy wartime organization. Furthermore, on 14 July, the 23rd Air Regiment, also, was absorbed into the same fleet. The Southwestern Area Fleet decided to attack outlying islands in the Arakura* area at the end of July 1946. As a part of this operation, the fleet ordered an attack on the Port Darwin area for a week, beginning 25 July. By this order, the 23rd Air Regiment carried out night attacks on 25 and 29 July.

On 30 July, 26 land attack planes and 26 fighters made daylight attacks. On the other hand, on 30 July, the forces of the 2nd Southern Expeditionary Fleet occupied the Dobo,* Joaru,* Rangoon, and Samuraki* areas.

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As soon as the Allied Forces took their first offensive action against the Japanese in the Solomons area in early August 1942, the war situation suddenly became concentrated in that area. In order to check the enemy operation in the Solomons area, our Navy air force, located in the northern Australia area, carried out a day attack on PORT DARWIN with a group of fighters and bombers on 23 August, and night attacks on 24 and 25 August.

At the end of August, the Grand Imperial Headquarters decided to transfer a part of the Naval Air Force, located in the Southwestern Area, to the Southeastern Area. This instruction No. 127 of the Navy Staff Section of the Grand Imperial Headquarters was issued on 31 August.

Instruction No. 127 of the Navy Staff Section of the Grand Imperial Headquarters

The Agreement of the Army and Navy Central Authorities Regarding Operations in Eastern NEW GUINEA and the Solomons Archipelago: Until the general conclusion of the present operation, the Army Air Force will guard and attack enemy ships in the Malay and Sumatra areas in connection with this operation. During this time, if the situation requires the Army Air Force will co-operate in the air defense of the Timor area.

In accordance with this order, 21 fighters, 12 land attack planes, and four land reconnaissance planes attached to the 23rd Air Fleet, left KUPAN* for the Southeastern Area on 6 September.

The Operation From Early Autumn 1942 to June 1943

During this period, operation of the Japanese Forces was concentrated in the Southeastern Area, especially upon the fierce battle on the Island of GUADALCANAL. Therefore,

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all available strength was used in the above operation and there were no new movements in the Southwestern Area; thus they merely carried on their formerly assigned mission with their existing strength.

The main operation which the Southwestern Area Force carried out during this time was the air attack on the northwestern coast of AUSTRALIA from the north of AUSTRALIA. In the beginning of Autumn, 1942, a part of the Navy Air Force strength in the Southwestern Area was transferred to the Southeastern Area, but day and night bombings on the northwestern coast of AUSTRALIA were still carried out more than once a month. However, the available air strength in the Southwestern Area gradually decreased with the progress of the situation of air combat in the Southeastern Area. On 15 Apr 43, the 21st Air Fleet, which was formerly stationed chiefly in the Andaman area, was removed from the Southwestern Area Fleet and was incorporated into the 11th Air Fleet (located in the Southeastern Area). Although the air strength in the Southwestern Area decreased to the same status as the 23rd Air Fleet (48 fighters, 36 land attack planes, and 16 sea planes), the air force carried out day attacks on the Port Darwin area twice in March and five times in May 1943.

In the meantime, enemy planes from the Port Darwin area gradually increased their attacks and raided the entire Arafura Sea area, early in 1943. However, during each raid, our Naval Air Force intercepted the enemy planes with fighters or sea-fighter planes with noteworthy results.

As mentioned above, the Agreement of the Army and the Navy Central Authorities regarding the defenses of the Lesser Sunda Islands, the Aru Islands, and Tanimbar Island was concluded in accordance with the instructions of the Navy Staff Section of the Grand Imperial Headquarters,

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issued on 15 Oct 42. By this Agreement, the Army sent the 48th and 5th Divisions to the Timor area and outlying islands in the Arafura Sea, strengthening these areas. The Navy escorted these troops. On 7 Jan 43, the Army established the 19th Army Headquarters to control these districts. On 15 Dec 42, the landing operations at MIMICA, on the southern coast of NEW GUINEA, were carried out with the ships HATSUKARI and TOMOZURU. About 270 officers and men succeeded in landing without encountering enemy counterattack.

On 18 December, the Commander-in-Chief of the Southwestern Area Fleet ordered an occupation of HOLLANDIA. On 25 December, the ships NATORI and ITSUKUSHIMA and two companies of the land combat unit advanced and occupied HOLLANDIA.

On 29 December, the Headquarters of 25th Naval Special Base Force was established to strengthen the defense of the western New Guinea area and to control this area.

On 15 Apr 43, a new Commander-in-Chief was appointed for the 2nd Southern Expeditionary Fleet which had formerly been a position occupied as an additional post of the Commander-in-Chief of the Southwestern Area Fleet.

On 25 Mar 43 the Grand Imperial Headquarters planned the third operation to meet the development of the war situation. This order was issued as Instruction No. 209 of the Navy Staff Section of the Grand Imperial Headquarters on the same date.

Instruction No. 209 of the Navy Staff Section of the Grand Imperial Headquarters (25 Mar 43).

The following are clauses concerning the Southwestern Area selected from the Imperial Navy plan for the 3rd operation:

1. The Navy will closely co-operate with the Army in

--22--

strengthening the defense of occupied areas in the South and to check enemy plans and attack from the air, or recapture these areas.

2. The Navy will carry out timely air combat against northwestern AUSTRALIA and will attempt to smash the enemy plans for counterattacks from these areas.

3. The Navy will secure sea and air supremacy in the eastern sector of the BAY of BENGAR to insure supply routes for BURMA and, at the same time, to repel enemy counterattacks in these areas.

4. The Navy will capture strategic points in southern NEW GUINEA at opportune times, as provided for in separate instructions.

5. The Navy will destroy enemy surface transport routes off the coast of INDIA and the western coast of AUSTRALIA by means of submarines and ships, if necessary.

6. At the opportune time, the Navy will co-operate with the Army in carrying out the occupation of Kokosu* Island and in launching surprise attacks on the enemy fleet and important points.

The most significant points in this plan for the 3rd operation are the counterattack on southern NEW GUINEA, mentioned in Clause 4 above, and the occupation of Kokosu* Island in Clause 6. Just when the war situation in the Southeastern Area, especially in the Solomons Archipelago, was growing tense, JAPAN'S only hope was to direct counterattacks, toward southern NEW GUINEA. This hope was expressed in this operational plan. However, actually, detached forces merely reconnoitered in the Mimica area, about the middle of 1943, with no results. The capture of Kokosu* Island was not realized.

About this time, reinforcements in the Andaman area were planned. In conjunction with the reinforcements by the Army, the Navy stationed the 8th Special Naval Landing

--23--

Force of KURE on Car Nicobar Island, one air defense unit and coast artillery unit on BLAIR, and one division of coast artillery on SABAN, at the end of July 1942.

VI. Operations From July 1943 to March 1944 The war situation in the Southeastern Area, which was briefly stalemated after the beginning of 1943, suddenly resumed an active phase with the invasion of NEW GEORGIA and eastern NEW GUINEA by the Allies at the end of June. The war situation was definitely unfavorable to the Japanese forces. In September, it became necessary to revise all the Army and Navy operations. This revision was stated in Instruction No. 280 of the Grand Imperial Headquarters Navy Staff Section issued on 30 September.

Instruction No. 2610 of Grand Imperial Headquarters Navy Section.

The following is an extract from the Agreement of the Army and Navy Central Authorities for Operations in the Central and Southern Pacific Areas:

The aim of the campaign provides that "The Imperial Army and Navy closely co-operate in destroying the invading enemy in strategic points in the Southeastern Area and must resist stubbornly. Meanwhile, they must complete measures for supporting a counter-offensive along strategic points from northern AUSTRALIA to the Central Pacific sector and must prepare fighting strength for a counterattack thereby carrying out a complete counterattack against the invading enemy and destroying it before it goes into action, so as to crush its fighting spirit."

In the outline of operational directions to be followed for this purpose were the following paragraphs concerning the Southwest Area:

--24--

1. The offensive position will be promptly strengthened by completing operational bases and strengthening the defense of strategic points in Northern AUSTRALIA, the CAROLINES,

and the MARIANAS, and by constructing operational bases and thus completing land, sea, and air strength in the Philippine area by the spring of 1944.

2. If the situation in AUSTRALIA permits, a positive campaign will be carried out after the middle of 1944. As to its method or direction of attack, this will be studied separately and necessary preparation will be made.

Regarding the maintenance of Army and Navy air bases in the northern Australian area, the following instructions were issued:

Appended Chart

Allotments concerning maintenance of air bases in the northern Australian area

(New Guinea area)

Bases

Present Situation

A. Main

B. Secondary

A. Secondary

B. Main

Usual Usage

Assigned for construction

HOLLANDIA

Ist

nearly completed

0

A B

"

IInd

newly completed

0

"

WAKDE

nearly completed

0

B

SARMI

Ist

IInd

newly completed

0

A

NUBOAI*

newly completed

0

A

SERUIBIAK*

Ist

IInd

newly completed

0

A

NABIRE

Ist

nearly completed

0

B

"

IInd

newly completed

0

B

--25--

Bases

Present

Situation

A. Main

B. Secondary

A. Secondary

B. Main

Usual Usage

Assigned for

construction

MUMI *

Ist - IInd

newly completed

0

A

LAKE AMAROE

Ist - Vth

newly completed

0

B

SORONG

Ist

IInd

newly completed

0

B

"

IIIrd - Vth

newly completed

0

A

MANOKWARI

Ist - Vth

newly completed

0

A

FAKFAK

Ist

IInd

newly completed

0

A

BABO

nearly completed

0

B

MATOWA *

Ist

nearly completed

0

B

"

IInd

newly completed

0

B

NAMIKA *

Ist

nearly completed

0

B

"

IInd

newly

completed

0

0

WAIBEM

Ist - IIIrd

newly completed

0

A

NUNHORU *

newly completed

0

A

SAGA *

under

construction

0

A

Ist - IIIrd

newly completed

0

B

(HALMAHERA, CERAM and other isolated islands)

Bases

Present Situation

A. Main

B. Secondary

A. Secondary

B. Main

Common use

Assigned for construction

ARU

No. 1

No. 2

newly completed

0

B

KEI

No. 1

No. 2

newly completed

0

B

TANIMBAR

No. 1

No. 2

newly completed

0

B

--26--

Bases

Present Situation

A. Main

B. Secondary

A. Secondary

B. Main

Common use

Assigned for

construction

AMBOINA

No. 1

nearly completed

0

B

"

No. 2

newly completed

0

B

BURA *

nearly completed

0

B

NAMLEA

No. 1

nearly completed

0

A B

"

No. 2

newly completed

0

A

ABU (SHIYA) *

under construction

0

A

"

No. 1

No. 2

newly completed

0

A

KAI

under construction

0

A

RINKATTO *

under construction

0

A

LIANG

under construction

0

A

HARUKU *

under construction

0

A

AMAHAI

under construction

0

A

BURA *

newly completed

0

A

WAHAI

newly completed

0

A

KAOE

No. 1

No. 2

newly completed

0

B

GARERA

newly completed

0

A

WASHIRE *

newly completed

0

A

SHAIRORO *

newly completed

0

A

RABUHA *

newly completed

0

A

--27--

(Timor, Sunda and Celebes)

Bases

Present Situation

A. Main

B.  Secondary

A. Secondary

B. Main

Common use

Assigned for construction

KOEPANG

nearly completed

0

B

"

No. 2

No. 3

newly completed

0

B

ATAPOEPOE

nearly completed

0

B

DILI

nearly completed

0

B

ABISU *

nearly completed

0

A

RAUTEN

EAST

WEST

nearly completed

0

A

HARIRURI

newly completed

0

A

KOEPANG

WEST

newly completed

0

A

WAINGAPPU *

nearly completed

0

B

SUMBA

No. 1

No. 2

No. 3

No. 4

newly completed

0

B

BISU

No. 1

nearly completed

0

B

"

No. 2

newly completed

0

B

NAMBASSAR *

No. 1

nearly completed

0

B

"

No. 2

newly completed

0

B

RAMBAN *

nearly completed

0

B

MALUMERA

nearly completed

0

A

BABI *

nearly completed

0

A

KANDARI

nearly completed

0

B

KANDARI

No. 2

No. 3

No. 4

No. 5

newly completed

0

B

--28--

Bases

Present Situation

A. Main

B. Secondary

A. Secondary

B. Main

Common use

Assigned for Construction

ANPESSIA *

No. 1

No. 2

No. 3

newly completed

0

B

POMARA *

No. 1

No. 2

newly completed

0

B

MACASSAR

nearly completed

0

B

RAIKAN *

newly completed

0

B

MASAMBA

newly completed

0

B

MANADO

0

B

MACASSAR

No. 1

No. 2

No. 3

newly completed

0

A

PINLAN *

No. 1

No. 2

newly completed

0

A

MUNA *

No. 1

No. 2

No. 3

newly completed

0

A

GORONTARO

No. 1

No. 2

newly completed

0

A

MANADO

No. 1

No. 2

newly completed

0

A

BALU *

No. 1

No. 2

newly completed

0

A

Note: A = Army

B = Navy

This alteration of the whole operation plan of the Imperial forces brought about a great change in the Southwest Area. That Is, the area ranging from Western NEW GUINEA to Northern AUSTRALIA, which had been regarded merely as being of secondary importance, suddenly became the main line of defense. Moreover, these areas were generally uncivilized and remote. Consequently, it was difficult to make immediate military preparations in them. The Navy had a small amount of military strength stationed for the defense

--29--

of these areas. These forces merely performed guard duty and made topographical surveys of the vicinity.

The essence of the defense plan for these areas which had newly become the main line of national defense, was the establishment of strong aerial fortifications in the western NEW GUINEA area (the SOLOMONS, BABO, and SAGA), and the launching of powerful aerial counterattacks against the enemy. At the same time, it was also planned to equip Kaoe Bay in HALMAHERA as a rear base. For these projects, investigations were carried out immediately and construction units were dispatched rapidly to the localities concerned.

Towards the end of 1943, the work had been begun, for the most part, and a great deal had been accomplished. However, when the Allied forces invaded the Biak Island area in May 1944, its equipment could not be fully utilized because of the unexpected enemy attack and because the construction required more work than expected. In order to strengthen these defenses, the troops were continually reinforced and, with the new organization of the 26th Special Base Force at HALMAHERA on 1 Nov 43 as the beginning, the 9th Squadron was organized for control of NEW GUINEA on 15 November. Furthermore, on 30 November, the 24th, 25th, and 26th Special Base Forces were combined and newly organized into the 4th Southern Expeditionary Force to assume control of western NEW GUINEA and northern AUSTRALIA.

During this period, our aerial operations along the northwestern coast of AUSTRALIA rapidly weakened with the decline of fighting strength. During August, September and November of 1943, land attack planes carried out scattered night attacks southeast of PORT DARWIN. However, by the end of the same year, even this became difficult. In direct opposition to this situation, aerial operations

--30--

by the Allied Forces from their bases on the northwest coast of AUSTRALIA rapidly became active. After the summer of 1943, the air supremacy of isolated islands in the Arafura Sea and Timor areas was In the hands of the enemy, and KENDARI, MACASSAR and BALIKPAPAN became their targets for attack. The enemy increased their attack day by day.

--31--

NETHERLANDS EAST INDIES, 1941

JAPANESE CENTRIFUGAL OFFENSIVE

DECEMBER 1941 - APRIL 1942

SOUTHERN ASIA, 1941

JAPANESE OFFENSIVE (AND CONTINUED OPERATIONS), JANUARY - MAY 1942

MICRONESIA, MELANESIA AND NEW GUINEA

JAPANESE OFFENSIVE

Japanese Fourth Fleet and South Seas Detachment Operations, December 1941 - April 1942