Japanese Monograph No. 169

OUTLINE OF NAVAL ARMAMENT AND PREPARATIONS FOR WAR

Part IV

PREPARED BY

MILITARY HISTORY SECTION

HEADQUARTERS, ARMY FORCES FAR EAST

DISTRIBUTED BY

OFFICE OF THE CHIEF OF MILITARY HISTORY

DEPARTMENT OF THE ARMY

FOREWORD

This is the fourth of a series of six monographs in regard to Japan's naval armament in preparation for and during the Pacific War.

Additional monographs covering Japan's naval armament plans

are:

Mono No

Outline of Naval Armament and Preparations for War, Part I

145

Outline of Naval Armament and Preparations for War, Part II

149

Outline of Naval Armament and Preparations for War, Part III

160

Outline of Naval Armament and Preparations for War, Part V

172

Outline of Naval Armament and Preparations for War, Part VI

174

26 July 1952

--iii--

PREFACE

Through Instructions No. 126 to the Japanese Government, 12 October 1945, subject: Institution for War Records Investigation, steps were initiated to exploit military historical records and official reports of the Japanese War Ministry and Japanese General Staff. Upon dissolution of the War Ministry and the Japanese General Staff, and the transfer of their former functions to the Demobilization Bureau, research and compilation continued and developed into a series of historical monographs.

The paucity of original orders, plans and unit Journals, which are normally essential in the preparations 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 G3 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.

Under the supervision of the Demobilization Bureau, the basic material contained in this monograph was compiled and written in Japanese by former officers, on duty in command and staff units within major units during the period of operations. Translation was effected through the facilities of Allied Translators

--v--

and Interpreters Service, G2, General Headquarters, Far East Command.

This Japanese Operational Monograph was rewritten in English by the Japanese Research Division, Military History Section, General Headquarters, Far East Command and is based on the translation of the Japanese original. Editorial corrections were limited to those necessary for coherence and accuracy.

--vi--

TABLE OF CONTENTS

Page

Chapter I

Situation from Outbreak of War to Revised Fifth Naval Armament Replenishment Plan

1

General Situation

1

Air Armament

1

Combat Air Groups

2

Training Air Groups

3

Transport Planes

4

Shipborne Planes

5

Air Personnel

5

Emergency War Production Expediting Department

5

Battleship Construction Stipulated in Fourth Plan

7

Increase of Aircraft Carriers

13

Chapter II

Revision of Fifth Naval Armament Replenishment Plan (Revised Fifth Plan)

19

Progress of Revised Fifth Plan

20

Ship Strength

20

Air Strength

30

Supplementary Adjustments to Revised Fifth Plan

41

Supplementary Ship Construction Plan to Revised Fifth Plan

42

Appendix I

Naval General Staff Secret No 191

49

Appendix II

Official Reply from the Ministry of Navy: Secretariat Secret Document No 9599-2

51

--vii--

Charts

Page

Chart No 1

Rearrangement of Titles of Plans

9

Chart No 2

Status of Plans

10

Chart No 3

Program for Expediting War Preparations

11

Chart No 4

Flan for Increasing Aircraft Carriers

15

Chart No 5

Shipbuilding Plan

21

Chart No 6

Approved Extraordinary Military Appropriations for Fiscal Year 1943

25

Chart No 7

Status of Naval Vessels in the Scheduled Shipbuilding Plan End of June 1942

29

Chart No 8

Detailed Status of Shipbuilding Plan End of June 1942

31

Chart No 9

Results' of Ship Construction Under the Revised Fifth Plan

35

Chart No 10

The Air Strength Increase Plan for Fiscal Year 1942 (Combat air group) (Shipborne air strength) (Training air group)

37

Chart No 11

Ships to be Completed End of Fiscal Year 1944

45

Chart No 12

Ships to be Completed End of Fiscal Year 1945

46

Chart No 13

Approved Budget and Actual Results Achieved 1944

47

--viii--

CHAPTER I

Situation from Outbreak of War to Revised Fifth Naval Armament Replenishment Plan

General Situation

The smooth progress of operations in the initial phase of the Pacific War led those in charge of the departments for war production to believe that the policy pertaining to such production was adequate. Later this was proven wrong and it became necessary to revise and strengthen methods of maintaining and stockpiling munition supplies. During this period, despite the fact that the Air Force played a vital part in the naval action off the Malayan coast, little attention was given to implementation of air armament or to the building up of the air force. The optimistic attitude of the time also led to delay in general national mobilisation, especially student mobilization for flight personnel.

As the lack of merchant shipping during the past few years had been held due to the expansion of naval armament, it was felt that in order to achieve the most effective results, the control of all shipbuilding should be under one head — the Navy Ministry. This was done soon after the outbreak of war.

Air Armament

In early February 1942, as it appeared that the Fourth Naval

--1--

Armament Replenishment Plan would be completed on time and the Fifth Naval Armament Replenishment Plan was moving forward smoothly, it was decided to regard the two plans as one from the beginning of the 1942 fiscal year.

The combat air groups, totalling 132 groups, were to be completed in five years according to previous plans and reorganization of air units was to be effected. Wartime strength was to be twice the planned peacetime strength.

A plan for training 156 air groups was to be completed in five years and the reorganization of the air units accomplished. Also, a total of 457 transport planes were to be prepared and maintained.

Combat Air Groups

The strength of combat air groups was to be more than double that of the Fourth Naval Armament Replenishment Plan and the plane complement aimed at approximately triple that of the Fourth Plan. An over-all change of air unit organization was to be made.

The reorganization of the Fourth Plan called for 65 groups with 1,032 aircraft as a normal complement and a reserve of 344, totalling 1,376 planes.

Reinforcements were to be 67 groups with 990 aircraft as a normal complement and a reserve of 330, totalling 1,320 planes.

The strength at the completion of the Fifth Plan would, therefore, be 132 groups with 2,022 aircraft as a normal complement and 674 as a reserve, totalling 2,696 aircraft. These air-

--2--

craft were to comprise:

Type of Aircraft

Number of Group

Number of Aircraft

Fighter

22

528

Fighter and bomber

13

312

Land reconnaissance plane

2

48

Medium land attack plane

15

360

Large land attack plane

10

240

Seaplane fighter

12

288

Seaplane bomber

9

144

Medium flying boat

12

144

Large flying boat

12

144

Patrol plane

8

128

Carrier fighter

3.5

84

Carrier attack plane

5.5

132

Reconnaissance seaplane

6

96

Large transport plane

2

48

Total

132

2,696

Training Air Groups

It was decided that the strength of the training air groups would be approximately two and a half times that stipulated in the Fourth Plan.

Up to the Fourth Plan 63 groups were completed with 894 aircraft as a normal complement and 639 as a reserve, totalling 1,533.

Reinforcements were to be 93 groups, comprising 1,270 aircraft as a normal complement and 848 as a reserve, totalling 2,118.

--3--

The total number of training air groups was to be 156, with 2,184 as a normal complement and 1,487 as a reserve, totalling 3,671 aircraft. This was to include 37 combat aircraft units to be reorganized.

The strength at the time of the completion of the Fifth Plan was to be:

Type of Aircraft

Number of Group

Number of Aircraft

Land training planes

30

720

Training seaplanes

16.5

396

Utility trainers

26.5

636

Small land combat planes

45.5

1,229

Medium land combat planes

10.5

252

Small combat seaplanes

19

342

Medium combat seaplanes

8

96

Grand total

156

3,671

Transport Planes

In consideration of the lessons learned from the China Incident and with the increase in land-based air strength, the necessity for a tremendous increase in the number of transport planes was recognized. A plan was formulated to prepare and maintain 457 aircraft by the end of 1946, comprising the following:

Large land aircraft

176

Large seaplanes

114

Small aircraft

167

Total

457

--4--

Shipborne Planes

A gradual increase in shipborne planes to 1,584, in accordance with the completion of vessels, was planned. Air Personnel

The plan called for 31,578 pilots — 10% officers, 40% special and warrant officers and 50% non-commissioned officers. Ordnance maintenance personnel was to total 10,013, including 250 officers, and aircraft maintenance personnel 35,078, including 1,335 officers,

Emergency War Production Expediting Department

Hitherto, the supervision of war production had been actually the responsibility of the section chiefs and their subordinate officers, but with the imminence of war it was felt that the chiefs of the bureaus and departments should, themselves, assume responsibility for the stepping up of production of vital war materials. The War Preparations Examination Department had been established for this purpose but it was a committee-type organization which drew up plans rather than executed them. Consequently, the Emergency War Production Expediting Department was established in November 1941 to supervise the execution of these plans. Headed by the Vice Minister of the Navy, its members comprised the chief of each bureau of the Navy Ministry, and of such departments as the Technical, Aeronautical and Civil Engineering, as well as the First (Operation) and Second (War Preparation) Bureau of the Naval General Staff. The Chief of the First Section of the Naval Affairs

--5--

Bureau was appointed secretary of the department.

Meetings were held weekly and extraordinary meetings were called whenever the occasion demanded. Reports were submitted on the actual progress of war production and explanations given of future plans.

The Emergency War Production Expediting Department functioned efficiently for the entire duration of the war as a center of war production activities.

The Emergency War Production Expediting Department first drew up a plan for expediting war production. This covered a period to March 1944, and every means available was used to complete the required armament and other war materiel requirements by that time.

During the second period - from April 1944 onward - special study was made on the execution of plans for the anticipated Revised Fifth Plan and various supplementary amendments were completed and successively decided and enforced.

With the decision to execute plans for expediting war preparations during the first and second period, the relationship with the various past armament and war production plans became extremely complicated and it was feared that confusion would be created in the various enforcing headquarters concerning the titles of these plans. In order, therefore, to rearrange and standardize these titles, the Chief of the Naval Affairs Bureau issued the following notification soon after the outbreak of the war:

--6--

Naval Affairs 1, Top Secret Document No 79

2 February 1942

From: Chief of the Naval Affairs Bureau, Navy Ministry

To: Chiefs of All Bureaus Concerned in Navy Ministry

Chief of Naval Technical Department

Chief of Naval Aeronautical Department

Chief of Naval Civil Engineering Department

Chief of the 1st and 2d Bureau of the Naval General Staff

Chiefs of Staff of All Naval Districts

Chiefs of Staff of All Guard Districts

Notification Regarding Rearrangement of the Title of the Execution Plans for Expediting War Preparations.

An order has been issued to start the first period execution plan for expediting war preparations. As to the second period execution plan, it has also been decided that all quarters concerned should pursue its study. In recognition of the fact that the relationship of these plans with the existing plans for war preparations have become fairly complicated, we beg to inform you that it has been decided the titles of all plans are to be rearranged and standardised henceforth as shown in the attached table (See Charts 1, 2 and 3).

Battleship Construction Stipulated in Fourth Plan

The following program for the construction of two battleships specified in the Fourth Plan was approved by the Navy Minister on 1 April 1939.

Temporary Name

Place of Construction

To be Started

To be Completed

No. 110 Warship Yamato-type

Yokosuka Navy Yard

Early April of 1940

Late March of 1945

No. 111 Warship Yamato-type

Kure Navy Yard

Early May 1941

Late October of 1945

--7--

The construction of No. 110 warship was initiated on 4 April 1940 as scheduled, and No. 111 warship on 7 November 1940, six months earlier than scheduled. The construction work on No. 110 was started with great enthusiasm as the project was the first of its kind in Yokosuka Navy Yard since the completion of the battleship Mutsu in 1921. In late 1940, soon after the keel had been laid, the work was delayed for approximately three months because of the design which called for reinforcement of the double bottoms under the engine compartments. Early in 1941 the progress of construction of these battleships was slowed down and finally ceased. The main reasons for this were the necessity to prepare existing large ships for battle, insufficient production of armor plates, and arguments on the advisability of continuing construction on battleships whose vulnerability was revealed by the battle lessons in the initial phase of the war. However, since considerable progress had already been made on the framework of No. 110 at Yokosuka Navy Yard, and its dismantlement would have been very difficult, it was decided to continue construction on this ship. Both navy yards, however, were confronted with the difficult task of meeting urgent war requirements and were unable to continue construction work on the battleships. After the Battle of Midway it was decided to convert No. 110 warship into an aircraft carrier.

As construction of No. 111 warship at the Kure Navy Yard had been started six months later than No. 110 warship, work had not progressed so far and it was considered possible to dismantle it.

--8--

Chart No 1

Rearrangement of Titles of Plans

Plan

Existing Abbreviations

Readjusted

Abbreviation

Classification of War Expediting Execution

Plan for fiscal year 1939

Fourth

Fourth

Plan for the first period

execution of expediting war preparations. Abbreviated as "War Expediting, First".

Supplementary temporary military appropriations for fiscal year 1941

Extraordinary

Wartime, First

Maritime shipbuilding program for fiscal year 1941

Urgent

Supplementary appropriations advanced from fifth Plan

Supplement

(March 1944)

Plans for fiscal year

Fifth

Wartime, Second

Plan for the second period execution of expediting war preparations. Abbreviated as "War Expediting Second".

+ A

Supplement

to Fifth

- B

Deletion from Fifth

A and B will be decided by the request of the Naval General Staff

Remarks

War Expediting, First = Wartime, First + Bulk of remainder of Fourth 4 + Advanced preparation of Fifth

(Note) Wartime, First = Extraordinary + Urgent + Supplement

War Expediting, Second = Wartime, Second + Discontinued or suspended part of Fourth + Remainder of Wartime, First

(Note) Wartime, Second = Fifth + A - B

(B contains the advanced preparation of Fifth to War Expediting, First)

--9--

Chart No 2

Status of Plans

--10--

Chart No 3

Program for Expediting War Preparations

--11--

This was done after the Battle of Midway.

Increase of Aircraft Carriers

The Fifth Plan had a relatively smooth start, but, as a result of the Battle of Midway, an immediate and basic change in the plan became necessary. Four aircraft carriers (the main strength of the naval air forces) had been lost. To cope with this situation, the Naval General Staff immediately initiated a study to change the basic policy of armament and war production having the increase of air strength and the construction of aircraft carriers as its main objectives. The Naval Technical Department drafted a plan for the immediate construction of aircraft carriers which it submitted to the Bureau of Naval Affairs and the Naval General Staff. It was later approved by the Ministry of the Navy. This plan, which was confirmed on 30 June 1942, was known as the Navy Secretariat Secret Document No. 8107.

The plan called for the conversion into aircraft carriers, as soon as possible of the Izumo Maru, Nitta Maru and Taigei Maru which were scheduled for completion during 1942. During 1943, the Argentina Maru, Scharnhorst, 2 seaplane tenders and the Brazil Maru were to be converted into aircraft carriers. A study was ordered on the replacement and use of destroyer engines for the Brazil Maru, however, the ship was sunk in August 1942, before work could be begun on it.

--13--

The actual dates of completion were:

Name of Ship

Scheduled Date of Completion

Actual Date of Completion

HIYO (IZUMO Maru)

31 Jul 42

31 Jul 42

CHUYO (NITTA Maru)

End of Nov 42

25 Nov 42

RYUHO (Submarine Tender TAIGEI)

End of Oct 42

30 Nov 42

KAIYO (ARGENTINA Maru)

End of Jul 43

23 Nov 43

SHINYO (SCHARNHORST)

End of Jul 43

15 Dec 43

CHITOSE (Seaplane Tender)

End of Aug 43

1 Jan 44

CHIYODA (Seaplane Tender)

End of Dec 43

31 Oct 43

BRAZIL Maru

(Plan was dropped)

No. 110 warship was to be converted into an aircraft carrier and work to be accelerated so that it would be completed by December 1944.

The construction of fourteen (14) Hiryu-type ships, including the No. 302 warship, and six (6) No. 130 warship-type ships, including the No. 130 warship, was to be accelerated to the utmost degree. (See Chart 4.)

In regard to equipping aircraft carriers, a study was ordered to be made to simplify equipment as much as possible, and any improvements learned from battle lessons were to be applied, as long as they did not delay the period of completion.

--14--

Chart No 4

Plan for Increasing Aircraft Carriers

Type of ship

Fiscal year

1942

1943

1944

1945

1946

1947

1948

HIRYU type

3

5

4

2

No. 130 warship type

1

1

2

2

Converted ships

3

1 (No. 110 warship)

Total

3

5

5

5

5

4

2

Remarks

A. Those under consideration are not included.

B. This plan may be changed in the future.

--15--

In accordance with the above-mentioned plan ships to be newly built are shown according to their types in the following table:

Classification

Type or Name of Ships

Number of Ships

Number of ships According to Fifth Plan

Remarks

Under the new shipbuilding plan

No. 302 type (HIRYU Type)

4

1

Six ships ware included under the initial plan, but ad a result of the decision to convert No. 101 warship late an aircraft carrier, two ships allocated to the Yokosuka Navy Yard were cancelled, reducing the total to four ships.

Improved Type (improved type of HIRYU)

9

0

Improved Type 130 (improved type of TAIHO)

5

2

Total

18

3

Under the existing shipbuilding plan

No. 110 warship (SHINANO)

1

Conversion of a battleship from Fourth Plan

No. 130 warship (TAIHO)

1

Fourth Plan

No. 302 warship (UNRYU)

1

Urgent Plan

Total

Grand Total

21

Chart No 4 (cont'd)

Classification

Name of Ship

Scheduled Date of Completion

Date of Completion

Remarks

New Warships

SHINANO (No. 110 Warship)

End of Dec 44

19 Nov 44

TAIHO (No. 130 Warship)

End of Jun 44

7 Mar44

UNRYU (No. 302 Warship)

End of Sep 44

6 Aug 44

AMAGI (No. 302 Type)

End of Dec 44

10 Aug 44

KUTSURAGI (No. 302 Type)

End of Mar 45

15 Oct 44

KASAGI (No. 302 Type)

End of Jun 45

(Unfinished

34%)

Launched on 19 October 1944.

Work suspension order issued on 1 Apr 1945.

ASO (No. 302 Type)

End of Sep 43

(Unfinished

60%)

Launched on 1 November 1944.

Work suspension order issued on 9 November 1944.

IKOMA (Improved Type)

End of Oct 45

(Unfinished

60%)

Work suspension order issued on 9 November 1944.

1944

Disposed of 17 November 1944.

Improved Type, 8 ships

(Building suspended)

Improved No. 130 Type, 5 ships

(ditto)

Chart No 4 (cont'd)

--17--

A special study was also ordered to be made of the problem of converting commercial ships into aircraft carriers for transporting aircraft. At the same time three ships of the Asama Maru class were to be converted into aircraft carriers, employing destroyer engines.

It was decided that shipbuilding and conversion work, in accordance with this plan, would be undertaken by the Yokosuka and Kure Navy Yards, as well as by the Kawasaki and Mitsubishi-Nagasaki Shipyards and that the manufacture of the required armor plates, elevators, windscreens, cranes etc. would be effected as emergency measures.

Emergency aircraft construction work progressed smoothly until the middle of 1943. After that, however, the sudden increase in urgent repair work on damaged ships, and the scarcity of materials and labor hindered this shipbuilding plan.

--18--

CHAPTER II

Revision of Fifth Naval Armament Replenishment Plan

(Revised Fifth Plan)

After the Battle of Midway, the Naval General Staff immediately revised the previously decided armament plan and the Fifth Plan. The main points of the new plan were:

Air strength was to be increased rapidly. The 132 units scheduled in the Fifth Plan were to be increased to 347, an increase of 215, and 100 units above the maximum wartime strength of 232 units authorised by the Fifth Plan.

The number of aircraft carriers was to bo increased immediately with the strength based on the Navy Secretariat Secret Document No. 8107.

More than 100 submarines were to be built and such forces as escorts, subchasers and other small anti-submarine ships were to be immediately increased.

The building of battleships and cruisers according to the Fourth Plan and Urgent Plan was to be suspended with the exception of the No. 110 warship which was to be converted into the aircraft carrier Shinano.

Front-line air bases were to be expanded and organized as quickly as possible against probable U. S. attacks.

Details of the plan were set forth in a formal request forwarded by the Chief of the Naval General Staff to the Minister of

--19--

the Navy. This request was known as Naval General Staff Secret Document No. 191 dated 30 June 1942. (See Appendix I.)

The official reply from the Ministry of the Navy on 3 August 1942, known as Secretariat Secret Document No. 9599-2 approving the plan and giving details of priorities to be followed is shown in Appendix II.

Progress of Revised Fifth Plan

Ship Strength

The Revised Fifth Plan, incorporating an enormous expansion in aircraft carriers, was an unprecedentedly large scale plan involving 361 ships with total tonnage of 1,156,061 tons. The shipbuilding plan and approved Extraordinary Military Appropriations for the fiscal year 1943 are shown on Charts 5 and 6. Furthermore, the prearranged work on naval vessels which the Naval Technical Department had on hand at the start of this plan (the end of June 1942), namely, the number of vessels called for in the earlier plan, which had not yet been completed, amounted to 410, as shown on Chart 7. Although the building of one battleship and two cruisers was cancelled with the implementation of the Revised Fifth Plan, it was decided to complete the work on the building of a total of approximately 780 craft, including eight converted aircraft carriers. Under the circumstances, it war most difficult to formulate the work allocation plan.

The spectacular military achievements during the initial stages

--20--

Chart No. 5

Shipbuilding Plan

Category

Individual Tonnage (standard displacement)

Number of Vessels

Total Tonnage

Type of Vessel

Maximum Speed and Cruising Range

Main Armament

Remarks

Aircraft Carrier

17,460

2

34,920

Hiryu Type

34.0

12.7cm Twin Mount Guns

6

18 - 8,000

25mm Triple Mount Machine Guns

13

Aircrafts

57

"

17,260

2

34,520

"

32.0

18 - 8,000

"

17,500

9

107,500

Improved Hiryu Type

34.0

12.7cm Twin Mount Guns

6

18 - 8,000

25mm Triple Mount Machine Guns

13

Aircrafts

53

"

30,360

5

151,800

Taiho Type

33.3

10cm Twin Mount Guns

8

18 40,000

25mm Triple Mount Machine Guns

22

Aircrafts

54

Flying Boat Tender

4,650

3

13,950

Akisushima Type

37.5

12.7cm Twin Mount Guns

2

14 - 7,500

25mm Triple Mount Machine Guns

2

Aircraft

1

Cruiser Otsu

8,520

2

17,040

New Type

37.5

15cm Twin Mount Guns

4

18 - 6,000

8cm Triple Mount Guns

4

25mm Triple Mount Machine Guns

3

Quadruple Torpedo Tubes

2

Aircraft

2

Submarine Tender

12,479

3

37,437

"

21.0

12.7cm Twin Mount Guns

2

16 -10,000

25mm Triple Mount Machine Guns

4

Aircraft

1

Emergency Net Layer

1,608

1

1,608

Improved Wakataka Type

20.0

8mm Triple Mount Guns

2

14 - 3,000

13cm Twin Mount Guns

2

Destroyer Ko

2,077

8

16,616

Yugumo Type

35.0

12.7cm Twin Mount Guns

3

18 - 5,000

25mm Triple Mount Machine Guns

2

Quadruple Torpedo Tubes

2

Destroyer Otsu

2,701

23

62,123

Akizuki Type

33.0

10cm Twin Mount Guns

3

18 - 8,000

25mm Triple Mount Machine Guns

2

Quadruple Torpedo Tubes

2

Submarine Ko

2,390

3

7,170

I-13 Type

17.7

14cm Gun

1

Speed and Cruising Range show those on surface.

The same applies to other submarines.

16 - 22,000

25mm Triple Mount Machine Guns

4

Torpedo Tubes

6

Aircrafts

1

"

2,486

3

7,458

New Type

22.4

14cm Gun

1

16 -16,000

25mm Triple Mount Machine Guns

4

Torpedo Tubes

6

Aircraft

1

Submarine Otsu

2,140

14

29,960

I-54 Type

17.7

14cm Gun

1

16 - 21,000

25mm Triple Mount Machine Guns

2

Torpedo Tubes

6

Aircraft

1

"

2,330

18

41,940

New Type

22.4

14cm Gun

1

16 -14,000

25mm Machine Guns

2

Torpedo Tubes

8

Aircraft

1

Submarine Hei

2,095

15

31,425

I-52 Type

17.7

14cm Guns

2

16 - 21,000

25mm Machine Guns

2

Torpedo Tubes

6

"

2,285

25

57,125

New Type

22.4

14cm Guns

1

16 -14,000

25mm Machine Guns

2

Torpedo Tubes

8

Submarine Medium

965

43

41,495

Ro-35 Type

19.7

8cm Gun

1

16 - 5,000

25mm Machine Guns

2

Torpedo Tubes

4

--21--

[--22-- blank]

Shipbuilding Plan (Cont'd)

Category

Individual Tonnage (standard displacement)

Number of Vessels

Total Tonnage

Type of Vessel

Maximum Speed and Cruising Range

Main Armament

Remarks

Submarine Special

3,530

18

63,540

New Type

19.7

14cm Guns

2

14 - 30,000

25mm Machine Guns

6

Torpedo Tubes

8

Aircraft

3

Escort

940

34

31,960

Ukuru Type

19.7

12cm Twin Mount Gun

1

16 - 5,000

12cm Gun

1

25mm Twin Mount Machine Gun

2

Depth Charges

120

Mine Sweeper

646

36

23,256

No 19 Type

20.0

12cm Guns

3

14 - 2,000

25mm Twin Mount Machine Gun

1

Depth Charges

36

Submarine Chaser

440

30

13,200

No 13 Type

16.0

8cm Guns

3

14 - 2,000

13mm Twin Mount Machine Gun

1

Depth Charges

36

Oil

Tanker

18,300

7

128,100

Hayasui

Type

16.5

12.7mm Twin Mount Machine Guns

2

9,000 tons of heavy oil and others for supply.

16 - 9,000

25 mm Triple Mount Machine Gun

2

Aircraft

6

"

15,600

124,800

New Type

20.0

12.7mm Twin Mount Machine Guns

2

6,800 tons of heavy oil and others for supply.

18 -10,000

25 mm Triple Mount Machine Gun

2

Aircraft

14

Storeship

910

7

6,370

Kinesaki Type

14.0

8cm Gun

1

Provisions

846 tons

12 - 3,500

13 mm Twin Mount Machine Gun

1

Fresh water

58 tons

Depth Charges

8

"

9,719

1

9,719

Irako Type

17.5

14 - 6,600

"

5,300

2

10,600

New Type

18.0

2cm Guns

2

Fresh provision.

450 tons

16 - 8,000

25 mm Twin Mount Machine Gun

2

Production material.

100 tons

Fresh water

500 tons

Target

Ship

2,540

5

12,800

"

33.0

13 mm Twin Mount Machine Gun

2

18 - 4,000

Depth Charges

18

Repair

Ship

9,600

2

19,200

Akashi Type

19.2

12.7cm Twin Mount Guns

2

14 - 8,000

25 mm Twin Mount Machine Gun

2

Survey

Ship

1,399

1

1,399

Tsukushi Type

19.7

14 - 8,000

Ice

breaker

7,040

1

7,040

New Type

17.0

12.7cm Twin Mount Guns

2

Icebreaking capacity: Approximately one meter thick.

14 - 5,500

25 mm Twin Mount Machine Gun

4

Aircraft

1

Light Mine Layer

720

12

8,640

Ajiro Type

20.0

12cm Guns

1

14 - 2,000

25 mm Twin Mount Machine Gun

1

Depth Charges

34

Motor

Torpedo Boat

75

18

1,350

Improved No 10 Type

30.0

25 mm Twin Mount Machine Gun

1

28 - 410

Torpedoes

4

Depth Charges

18

Total

361

1,156,061

--23--

[--24-- blank]

Chart No 6

Approved Extraordinary Military Appropriations for Fiscal Year 1943

Category

Individual Tonnage

Number of Vessel

Unit Price per Ton (in Yen)

Unit Price per Individual Vessel (In 1,000 yen)

Total Sum for the Category

(in 1,000 yen)

Remarks

Cruiser (Otsu)

3,520

2

5,678

4[],380

96,760

Flying Boat Tender

4,650

3

5,221

24,273

72,834

Emergency Net Layer

1,610

1

4,890

7,873

7,873

Aircraft Carrier (No 302 Type)

17,250

13

5,417

93,442

1,214,746

Aircraft Carrier (Improved No 130 Type)

30,400

5

4,294

130,550

652,750

Destroyer (Ko)

2,600

8

7,048

18,325

146,600

Destroyer (Otsu)

2,930

23

6,441

19,194

441,462

Submarine (Ko)

2,490

6

8,676

21,604

129,624

Submarine (Otsu)

2,282

32

9,187

20,965

670,880

Submarine (Hei)

2,240

40

9,428

21,119

844,760

Submarine (Medium)

1,000

43

8,686

2,686

373,498

•

Submarine (Special)

3,500

18

3,246

28,861

519,498

Submarine Tender

12,580

3

2,672

33,612

100,336

Escort

1,200

34

5,167

6,200

210,800

Submarine Chaser

420

30

6,948

2,918

87,540

Line Sweeper

700

36

5,621

3,935

141,660

Light Mine Layer

720

12

6,232

4,427

53,844

Oil Tanker (No 304 Type)

13,400

7

827

15,216

106,512

--25--

[--26-- blank]

Approved Extraordinary Military Appropriations for Fiscal Year 1943 (Cont'd)

Category

Individual Tonnage

Number of

Vessels

Unit Price per Ton (in Yen)

Unit Price per Individual Vessel (in 1,000 yen)

Total for the Category (in 1,000 yen)

Remarks

Oil Tanker (New Type)

15,900

8

1,062

16,883

135,064

Icebreaker

6,800

1

2,432

16,538

16,538

Storeship (No 74 Type)

9,600

1

1,310

17,378

17,378

Storeship (New Type)

5,500

2

2,389

15,391

31,782

Storeship (No 261 Type)

1,000

4

2,923

2,928

11,712

Seven in the Plan

Survey Ship

1,600

1

4,710

7,536

7,536

Repair hip

9,420

2

2,444

23,027

46,054

Bomb Target Ship

3,000

5

3,355

10,064

50,320

Motor Torpedo Boat

100

18

23,850

2,385

42,930

Total

358

6,231,791

Note: The following was added in the fiscal year 1944 to equip oil tankers to carry aircraft.

No 304 Type

29,064,000 yen for seven ships; (¥ 4,152,000 per individual ship)

New Type

75,216.000 yen for eight ships; (¥ 9,402,000 per individual ship)

Total

104,280,000 yen

--27--

[--28-- blank]

Chart No 7

Status of naval vessels in the scheduled shipbuilding plan as at the end of June 1942.

Category

Not yet laid down

Already laid down

Already launched

Total

Remarks

Battleship

0

2

1

3

Third Plan:

MUSASHI

Fourth Plan

No 110 warship converted into aircraft carrier (SHINANO)

No 11 warship

suspended and dismantled.

Aircraft carrier

2

0

0

2

Flying boat tender

1

0

0

1

Cruiser

2

3

3

8

2 craft suspended (one each from Fourth & Urgent). Work on one craft temporarily suspended after launching (Urgent Plan: IBUKI)

Destroyer

25

8

6

39

Submarine

53

26

19

Escort

24

6

0

30

Minesweeper

24

6

1

31

Subchaser

15

9

4

28

Light minelayer

16

2

1

19

Auxiliary vessels

8

4

3

15

Light auxiliary vessels

96

39

1

136

Total

266

105

39

410

Of the total, three craft suspended or

cancelled.

Details are as shown in Charts 8 and 9

--29--

of the war added great impetus to the volume of work put out by all navy yards and private dockyards to which work was assigned.

However, with the increasing number of damaged ships entering the port, shortage of materials, and the gradual diminishing number of workers coupled with successive demands for newly planned smaller naval vessels arising from the new war situation, the substance of the Revised Fifth Plan changed daily. The results finally achieved are shown in Charts 8 and 9. Air Strength

Combat Air Groups: The operational forces, together with the carrier and tender reserve forces at home and abroad, totalling 347 units (an increase of 219 units over the Fifth Plan and 83 units over the Fifth Wartime Plan) or 105 air groups (52 combat air groups assigned at home and 53 combat air groups assigned abroad) totalling 7,832 planes, combining the normal complement and immediate reserve, were to be maintained. (See Chart 10.)

Training Air Groups: 183 training air units (under 45 training air groups) were to be maintained. This was an increase of 27 units over the Fifth Plan. The normal complement of planes plus the immediate reserve was to be 4,939. (See Chart 10.)

Shipborne Air Strength: 129 units were to be maintained. The normal complement plus immediate reserve planes were to total 2,467. (See Chart 10.)

936 transport planes were to be maintained. (See Chart 10.)

--30--

Details - 2 -

Name of Plan

Category

Number of ships planned

Number of Unfinished Ships

Remarks

Not yet laid down

Already

laid

down

Already

launched

Total

"Urgent"

Cruiser

2

0

2

0

2

Ibuki and others

Aircraft Carrier

1

1

0

0

1

Unryu

Flying Boat Tender

1

1

0

0

1

Destroyer (Ko)

16

14

2

0

16

Hayanami and others

Destroyer (Otsu)

10

10

0

0

10

Shimozuki and others

Submarine (Otsu)

6

1

5

0

6

Submarine (Hei)

6

6

0

0

6

Submarine (Medium)

12

10

2

0

12

Submarine (Small)

9

7

2

0

9

Escort

30

24

6

0

30

Minesweeper

28

24

4

0

28

Subchaser

20

15

5

0

20

Light Minelayer

14

14

0

0

14

Auxiliary Subchaser

100

67

33

0

100

Auxiliary Minesweeper

16

11

5

0

16

Tanker

4

3

1

0

4

Kazahaya type

Motor Torpedo Boat

18

18

0

0

18

Total

293

226

67

0

293

"Supplement"

Submarine (Ko)

2

2

0

0

2

Submarine (Otsu)

12

9

3

0

12

Submarine (Medium)

15

15

0

0

15

Submarine (Refueling)

3

3

0

0

3

Target Ship

1

1

0

0

1

Total

33

30

3

0

33

--33--

[--34-- blank]

Chart No 9

Results of Ship Construction Under the Revised Fifth Plan

Category

Number of Ships

Planned

Completed

Under

construction

Not yet started or cancelled

Aircraft

18

2

3

13

Flying boat tender

3

0

0

3

Submarine tender

3

0

0

3

Cruiser

2

0

0

2

Emergency net layer

1

0

0

1

Destroyer

31

0

0

31

Submarine (Ko)

6

1

2

3

Submarine (Otsu)

32

0

0

32

Submarine (Hei)

40

0

0

40

Submarine (Medium)

43

0

0

43

Submarine (Special)

18

3

1

14

Escort

34

12

4

18

Minesweeper

36

0

0

36

Subchaser

30

3

0

27

Oil tanker

15

0

0

15

Storeship

10

0

0

10

Target ship

5

1

1

3

Repair ship

2

0

0

2

Survey ship

1

0

0

1

Ice breaker

1

0

0

1

Light minelayer

12

0

0

12

Motor Torpedo boat

18

0

0

18

Total

361

22

11

328

--35--

Flight personnel were estimated at 40,500. The number of teams of flight personnel for large planes was to be twice the number for the wartime plane complement and for other types of planes the number was to be one and a half times the normal complement. The required number of personnel for training groups was to be maintained constantly.

Flight engineers were estimated at 2,470 and the assigned personnel ratio was to be the same as for flight personnel. Aircraft engineers were to total 57, 800 and ordnance engineers 19,400.

In order to execute this plan, it was necessary to emphasize aircraft production as a national policy and to take measures to give top priority to the Navy with regard to the allotment of mate-rials.

It was evident from the Navy Minister's reply to the Chief of the Naval General Staff that it was considered that there were many problems to overcome. Principal among these was the fact that if the rate of consumption of materials in the future was to be assumed to be the same as that during the four months from the outbreak of war to the end of March 1942, a delay of a year could be anticipated in the completion of planes. The anticipated date of completion would then be the end of the fiscal year 1947. Also, if the complement of flight personnel were increased by the approximate rate of 1.2 times the plane complement, their training would be generally completed in parallel with the rate of manufacture of the planes.

36

Chart No 10

The Air Strength Increase Plan for Fiscal Year 1942 (The Revised Fifth Plan)

The combat air group

Air Strength

Category

Number of Planes

per Air Unit

Required Number of

Air Unit in Revised Fifth Plan

Required Number of Air Units in Fifth Plan (Wartime Strength)

Increase or decrease of Air Units In Revised Fifth Plan

Land-based

air strength

Land fighter Plane

18/6

100

44

(+) 56

Fighter-bomber

60

26

(+) 34

Land reconnaissance Plane

9

4

(+) 5

Land attack

Large

10

20

(-) 10

Plane

Medium

60

30

(+) 30

Seaplane fighter

12

22

(-) 10

Seaplane bomber

12/4

18

18

0

Patrol Plane

26

16

(+) 10

Transport Plane

18/6

4

4

0

Flying Boat

Large

9/3

0

24

(-) 21

Medium

12

24

(-) 12

Air strength prepared

for converted

vessels

Carrier fighter

18/6

13

7

(+) 6

Carrier bomber

20

11

(+) 9

Carrier attack Plane

Carrier reconnaissance Plane

3

0

(+) 3

Seaplane fighter

0

2

(-) 2

Reconnaissance Seaplane

12/4

0

12

(-) 12

Total

347

264

(+) 33

Note: The strength of Large land attack planes in wartime is the same as that in peacetime.

The combat air group figures shown are wartime; the strength in peacetime was one half the wartime strength.

--37--

[--38-- blank]

Chart No 10 (cont'd)

Shipborne air strength

Carrier planes: 106 units (Number of aircraft of one unit: 18 normal complement and 6 immediate reserves)

Seaplanes: 23 units (Number of aircraft of one unit: seaplane fighters, 18 end 6; reconnaissance seaplanes, 12 and 4) Transport planes

To be assigned in accordance with the following:

Units to which planes will be assigned

Standard of assignment

Remarks

Land attack plane unit

Three large planes for one air unit

Flying boat unit

Two large planes for one air unit

Land base small plane unit

One large plane and one small plane for one air unit

Carrier plane unit

One-half of the number prescribed by the standard of assignment at the time of actual loading shall be maintained.

Shipborne seaplane unit

Training unit

One large plane and one small plane for one air group

Navy Ministry and Navy Guard Districts

One large plane and one small plane for each naval district and guard district; two large planes and two small planes for the central office.

Total..........926 planes

39

Chart No 10 (Cont'd)

The training air group

Category

Number of planes per unit

Required number of Air Units in revised Fifth Plan

Required number of Air Units in Fifth Plan

Training aircraft

12/12

93.0

183.0

73.0

156.0

Combat aircraft

Same as number of aircraft of combat air unit, but the number of combat aircraft of the pilot-observer training unit shall be the same as that of its reserve aircraft.

90.0

83.0

--40--

If the complement were increased by 1.5 times, the completion of the training would be delayed another year, or until the end of the fiscal year 1948.

Although the naval authorities started the plan with high hopes of its successful completion, many difficulties confronted them, both because of the unprecedentedly large size of the plan and also because the operational situation had begun to deteriorate. The production increase of aircraft failed to show the expected progress and losses increased tremendously. During the fall of 1942, in the Southeast Area, the annual loss of planes rose to 95 percent. Thus, the plan which was intended to be the main prop of strength maintenance until the termination of the war, had to be adjusted gradually with various emergency supplementary plans as operations developed, in order to meet new situations as they arose.

Supplementary Adjustments to Revised Fifth Plan

The whole substance of the Revised Fifth Plan, through successive heated deliberations since the outbreak of the war and through a drastic revision as the result of the Battle of Midway, was finally decided in early August, 1942 and put into motion. The Chief of the Naval Affairs Bureau of the Navy Ministry submitted the following notification to the authorities concerned on 30 September, 1942 in order to notify them that the name of the revised plan had been abbreviated to "Revised Fifth Plan" and to obtain a

--41--

unanimous understanding as to the relation between the Revised Fifth Plan and the War Preparation Acceleration and Execution Plan.

Naval Affairs Bureau First Secret Document No. 738

30 September 1942

From: Chief of Naval Affairs Bureau, Navy Ministry

To: Chiefs of Bureaus concerned, Navy Ministry

Chief, Naval Technical Department

Chief, Naval Aeronautical Department

Chief, Naval Civil Engineering Department

Chief, First Bureau, Naval General Staff

Chief, Second Bureau, Naval General Staff

Notification Concerning the Abbreviation of the Name of the New Armament Plan.

It shall be understood that those plans of the requested naval strength mentioned in the Naval General Staff Document No. 191 (Wartime Plan for the Fiscal Year 1942), with the exception of the plan for the fiscal year 1939 (Fourth) and the Wartime Plan for the Fiscal Year 1941" (Urgent) will be known by the abbreviated title of "Revised Fifth Plan".

It shall be known that in reference to the relation between the abovementioned plan and the War Preparation Acceleration and Execution Plan, the latter's strength will correspond to that which is represented by the formula "Fifth + A - B".

Supplementary Ship Construction Plan to Revised Fifth Plan

Soon after the Revised Fifth Plan was begun the war developed into a large scale war of attrition, struggling for the control of the Southeast Area. Therefore, the Naval General Staff demanded the construction of an additional 18 submarines (Type TEI) in October 1942, and 42 destroyers (Type TEI) in early 1943.

The following Naval General Staff Secret Documents No. 309 and No. 37 refer to this construction.

--42--

Naval General Staff Secret Document No. 309

21 October 1942

From: Chief of Naval General Staff

To: Navy Minister

Request concerning Additional Ship Construction to the Wartime Air Strength Expansion and Ship Construction and Replenishment Plan for Fiscal Year 1942.

In view of the development of the situation in the Greater East Asia War, I hope the abovementioned request will be accepted and initiated in accordance with the program mentioned in the annexed document.

(Annex Document)

Supplementary Wartime Ship Construction and Replenishment Plan for Fiscal Year 1942

The plan shall be commenced in fiscal year 1942 and completed by the end of 1944.

The ships to be constructed and their main essentials are shown on Chart No. 11.

Naval General Staff Secret Document No. 37

2 February 1943

From: Chief of Naval General Staff

To: Navy Minister

Request Concerning Additional Ship Construction for the Wartime Air Strength Acceleration and Ship Construction Replenishment Plan for Fiscal Year 1942.

In view of the development of the war situation since the start of the Greater East Asia War and taking into consideration its future development, we believe that it is of vital importance to increase the number of destroyers. Therefore, we hope that you will accept the request and initiate the execution of the project in accordance with the plan in the annexed document.

Annexed Document

The Second Supplementary Plan for Wartime Ship Construction and Replenishment Plan for Fiscal Year 1942

--43--

The plan shall be started in the fiscal year 1943 and completed by the end of the fiscal year 1945.

The ships to be constructed and their main essentials are shown on Chart No. 12.

The Navy Ministry fully acknowledged the operational demands of this plan but felt that if it were put into force at this time great confusion would result. The Revised Fifth Plan, had just been started and the Execution Plans for Expediting War Production (First Period) were under way. It was decided, therefore, that the execution of the proposed plan should be studied first and then woven into the Execution Plans for Expediting War Production (Second Period) which were to be determined in the near future. Moreover, budgets and items were to be disposed as supplements to the Revised Fifth Plan.

The approved budget and details of the actual results achieved are shown on Chart No. 13.

--44--

Chart No 11

Ships to be Completed End of Fiscal Year 144

Category

Number of Ships

Standard Displacement

Speed

Cruising Range

Other Essentials

Subseries (TEI)

11

approx 1,500 tons

Surface over 12 knots

Submerged speed approx 6 knots

Surface cruising range approx 15,000 s. miles at 10 knots. Submerged cruising range approx 60 m. miles at 3 knots.

1. 40 caliber 14cm gun

1

2. Two 25mm single mount machine guns. Portable type which can be mounted at the leading deck of the special type cargo lighters.

3. Two 53cm bow torpedo tubes

Two torpedoes

4. Main Personnel and Arms Loaded

a. Land combat personnel

approx 110

b. Land combat equipment

approx 10 tons

c. Special landing barges

2

d. Special rubber boats

several

5. Others

a. Submersible limit

75 esters

b. Continuous cruising endurance

approx 2 months

e. Special consideration shall be given for

equipping so that loading and unloading will be done promptly and easily.

--45--

Chart No 12

Ships to be Completed End of Fiscal Year 1945

Category

Number of

Ships

Standard Displacement

Speed

Cruising Range

Other Essentials

Destroyer (TEI)

42

1,250 tons

approx

2[] knots

Approx 3,500

n. miles at 18 knots

1. One 12.7cm twin mount dual purpose gun

One 12.7cm twin mount dual purpose gun

2. Four 25mm triple mount machine guns

3. One 53cm six mount torpedo tubes

Six torpedoes

4. Thirty-six depth charges

Two depth charge throwers

5. One echo ranging set

One hydrophone

6. One radar

7. Two 10 M Special cargo lighters

Two cutters

--46--

Chart No 13

Approved Budget and Actual Results Achieved 1944

Category

Tonnage

Number of Ships

Cost per Ton

in yen

Cost per Ship in Thousand Yen

Total

in Thousand Yen

Remarks

Destroyer (TEI)

1,260

32

7,041

9,326

29,432

Approved in the fiscal year 1944

"

"

10

7,430

9,614

96,140

Approved in the fiscal year 1945

Submarine (TEI)

1,500

11

6,289

9,426

103,686

Approved in the fiscal year 1944

Total

53

498,258

Total in Revised Fifth Plan

411

6,730,049

Actual Results

Category

Number of Ships

Planned

Completed

Under constuciton

Not yet started or cancelled

Destroyer (TEI)

42

26

5

11

Submarine (TEI)

11

11

0

0

Total

53

37

5

11

Total in Revised Fifth Plan

414

59

16

339

--47--

Chart No 13 (cont'd)

Category

Individual Tonnage (Standard Displacement)

Number of

Ships

Total Tonnage

Type

Top Speed and Cruising Range

Main Armament

Destroyer (TEI)

1,262

42

53,004

New Type

27.8 knots

3,500 n. miles at 16 knots

One 12.7cm twin mount gun

One 12.7cm single mount gun

Four 25mm triple mount machine gun

One 03 Type torpedo tube.

Submarine (TEI)

1,470

11

16,170

a

13.0 knots

15,000 n. miles at 10 knots

One 14cm gun

Two 25mm machine guns

Two torpedo tubes

Total

53

69,174

Total in Revised

Fifth Plan

414

1,225,235

--48--

Appendix I

Naval General Staff Secret No 191

30 June 1942

To: Minister of the Navy

From: Chief of the Naval General Staff

Request Concerning Increase of Wartime Air Strength and Building and Replenishment of Navy Vessels for Fiscal Year 1942.

In reference to the building and replenishment of Navy vessels and an increase in air strength, requests were previously forwarded for the plan for the fiscal year 1942, and later, with the opening of hostilities for the wartime plan for the fiscal year 1941. In view of subsequent developments and the enforcement of an enormous armament expansion program by the U.S. Navy, it has become urgently necessary to replenish and maintain wartime armament by revising a portion of the previously determined plans. Accordingly, I request you to take the necessary steps to execute this measure as set forth in the attached plan.

Attached Plan

Wartime Air Strength Expansion and Ship Replenishment Plan for Fiscal Year 1942.

In view of the battle lessons gained since the outbreak of war,

the development of the war situation and the enforcement by the U.S.

Navy of a gigantic armament expansion plan, strength most suitable

for bringing the war to a successful conclusion shall be selected

and be held in readiness.

--49--

In consideration of materials available and productive capacity, at this juncture, strength absolutely indispensable shall be held in readiness, according to the following order of urgency: Aircraft

Aircraft carriers

Submarine and anti-submarine forces

Other naval vessels

With regard to the expansion of air strength, the contents of the Fifth Plan shall be revised in accordance with the following policy and the completion of the pre-arranged plans shall be expedited to the utmost.

Aircraft

In view of our progress in experiments in the light of current battle lessons and our production capacity, in order to meet the changing situation, production emphasis shall be placed on aircraft of such types as are most needed for promoting the war. Air Bases

Emphasis shall be placed on front-line bases according to the changes in the situation. The maintenance of air bases in the homeland area shall, for the time being, be limited to minimum requirements.

Expansion of Air Strength

The First Phase Air Strength Plan, included in Ship Replenish-

--50--

Chart. No 1

Land-based Air Strength

Strength

Kind of aircraft

Normal plane complement for one air unit

Number of units required

Number of units called for Fifth Plan

Increase or decrease in number of units after revision

Land based air strength

Land fighter plane

Interceptor

18

40

44

(+) 56

Long range fighter

60

Fighter-bomber

60

26

(+) 3A

Land reconnaissance plane

9

4

(+) 5

Land attack

Large

10

20

(-) 10

Medium

60

30

(-) 30

Seaplane fighter

12

22

(-) 10

Seaplane bomber

12

18

18

0

Patrol plane

26

16

(+) 10

Transport plane

18

4

4

0

Flying boat

Large

9

0

24

(-) 24

Medium

12

24

(-) 12

Air strength replacement for carrier borne planes

Carrier fighter

15

13

0

(+) 13

Carrier attack plans

20

0

(+) 20

Carrier bomber

Carrier reconnaissance plans

3

0

(+) 3

Total

347

232

(+) 115

--51--

ment and Air Strength Expansion Plan for Fiscal Year 1942 contained in Naval General Staff Secret Document No. 471, shall be revised as follows:

Land-based air strength

The land-based air strength shown on Chart I indicates wartime strength. The immediate reserve of planes shall be one-third of the normal plane complement.

Although the number of large land attack plane units is 10 for the time being, speedy construction of a further 10 units during and after the fiscal year 1947 shall be considered.

Although peacetime strength is considered to be generally one-half of the wartime strength, conferences shall be held in accordance with the situation at the time of the conversion. Shipborne air strength

Kind of aircraft

Normal plane complement for one air unit

Number of units necessary for standing vessels

Number of units necessary for converted ships

Total number of air units

Carrier fighter

18

33

5

38

Carrier bomber

51

9

60

Carrier attack plane

Carrier reconnaissance plane

8

0

8

Seaplane fighter

2

0

2

Reconnaissance seaplane

12

13

8

21

Total

107

22

129

--52--

Land-based Air Strength

Strength

Kind of aircraft

Normal plane complement for one air unit

Number of units required

Number of units called for Fifth Plan

Increase or decrease in number of units after revision

Land based air strength

Land fighter plane

Interceptor

18

40

44

(+) 56

Long range fighter

60

Fighter-bomber

60

26

(+) 3A

Land reconnaissance plane

9

4

(+) 5

Land attack plane

Large

10

20

(-) 10

Medium

60

30

(+) 30

Seaplane fighter

12

22

(-) 10

Seaplane bomber

12

18

18

0

Patrol plane

26

16

(+) 10

Transport plane

18

4

4

0

Flying boat

Large

9

0

24

(-) 24

Medium

12

24

(-) 12

Air strength replacement for carrier borne planes

Carrier fighter

15

13

0

(+) 13

Carrier attack plane

20

0

(+) 20

Carrier bomber

Carrier reconnaissance plane

3

0

(+) 3

Total

347

232

(+) 115

The immediate reserve of planes shall generally be limited to approximately one-third of the normal plane complement, part of which shall be placed on board ships and the remainder held in readiness at the replacement bases for carrier-borne planes and inner combat bases.

Training air units

Kind of aircraft

Normal plane complement for one air unit

Number of units required

Total No. of air units

Training plane

12

93.0

183.0

Combat aircraft

Same as combat air unit

90.0

The immediate reserve of training planes shall consist of the normal plane complement.

The number of combat aircraft for pilot and reconnaissance training units shall be the same as the normal plane complement and for other training air units it shall be one-third of the normal plane complement, with the exception of flying boats, which shall be same as the normal complement.

Training planes

Transport planes shall be held in readiness in accordance with the following:

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Units

Standard of assignment

Remarks

Land attack plane

3 large planes for one air unit

Equivalent to one-half of shipborne shall be held in readiness.

Flying boat

3 large planes for one air unit

Land based small aircraft

2 large planes for one air unit

Carrier plane

Shipborne seaplane

Training air group

1 large and 1 small planes for one air group

Navy District, Guard District and Navy Ministry

1 large plane and I small plane for Naval District, Guard District and Fleet Headquarters. 2 large planes and 2 small planes for the central authorities.

Flight personnel

In regard to the personnel of units committed in an operation, the number of teams shall be twice that required for large planes of wartime normal plane complement and one and a half times for other types of planes. The training shall train personnel so as to meet these requirements.

Ten thousand (10,000) pilots and observers shall be trained each year during the war after the fiscal year 1945, and, 10 percent of this number shall be earmarked as reserve personnel.

Up to 2,800 officers, shall be trained immediately and assigned

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to posts of the Division Officer or lower posts. Air Group and Air Base

Operational air bases and carrier-borne plane replenishment bases shall be organized by the end of the 1946 fiscal year in accordance with Chart 2 and the air groups and base units shall be organized according to the demand of the operations. The air group disposition program during the completion of this revised plan shall be as shown on Chart 3. However, it may be changed according to future operations and other conditions.

Construction and Replenishment of Ships

Ships Stipulated in the Construction Plan for Fiscal Year 1939 No. 110 Warship;

The warship shall be converted into an aircraft carrier by the end of 1944. Essential particulars shall be discussed later. No. 111 Warship;

Construction shall be discontinued and the ship shall be immediately dismantled.

No. 137 Warship;

Construction shall be discontinued.

Ships Stipulated in the Wartime Construction Plan for Fiscal Year 1941

No. 300 Warship;

This ship shall be launched quickly but further work shall then be suspended.

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No. 301 Warship:

The construction shall be discontinued.

The first period plan shown in the Naval General Staff Secret Document No. 471 shall be revised as shown in Chart 4 and completed by the end of 1947.

In regard to increasing the number of converted aircraft carriers, discussion shall be held later.

Ships to be constructed, both essential particulars of new and improved Fifth Plan type are as shown in Chart 5.

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Appendix II

Official Reply from the Ministry of Navy:

Secretariat Secret Document No 9599-2

3 August 1942

From: Minister of Navy

To: Chief of Naval General Staff

Reply to the Request Concerning the Wartime Reinforcement of Air Strength and Additional Construction of Vessels for Fiscal Year 1942.

Although it is anticipated that, in view of the current situation, many difficulties will be encountered in executing the above-mentioned matters requested in the Naval General Staff Secret Document No 191, every effort will be exerted to meet your wishes. As for the details of the plan, the Vice-Minister of Navy, will communicate with the Vice-Chief of Naval General Staff in regard to details of the plan,

(The End)

Reference Material Added to the Reply

30 July 1942

From: Bureau of Naval Affairs, Navy Ministry

Prospect of maintaining the Strength Requested in Naval General Staff Secret Document No 191.

Air Strength: The date scheduled for the completion of air—

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craft should be decided in accordance with production capacity and the rate of loss. Therefore, if we estimate the future rate of loss from the outbreak of war to the end of last March as a provisional basis, it is expected that the plan will be completed at the end of fiscal year 1947. The training of personnel will be approximately 20 percent more than the complement believed necessary generally for the completion of the plan. In case 50 percent more personnel than the complement is required, the completion of training will be delayed a further year.

As the maintenance of patrol planes and fighter-bombers cannot possibly meet the demand of the Naval General Staff, it is deemed necessary to substitute other types of planes for them and that further study and investigation be conducted as to the capabilities of maintaining air bases and disposing of strength.

Naval Vessels: The current situation is such that the completion of the construction of Navy vessels must inevitably be delayed approximately one year chiefly because of the shortage of materials and labor. Furthermore, there are many production installations of various types which, in executing this plan, require expansion or new construction. Although concrete measures are being studied, it is impossible, for the time being, to make ample preparations for expanding the dry docks, mooring docks and supply facilities required for the increase in strength of naval vessels. Furthermore, an increase in the number of damaged ships to be repaired will exert considerable influence upon the execution

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of the plan.

Construction of Merchant Ships: Shipping space is an absolutely necessary factor in the prosecution of a war. In view of the fact that the construction of merchant vessels since the outbreak of the war has failed to make as good progress as anticipated, various emergency measures are now being studied. One is to put the construction of merchant vessels under the single control and jurisdiction of the Navy by regarding it as part of the naval armament; another is aimed at the smooth supply of materials and labor. It is impossible to maintain naval vessels by restricting the construction of merchant ships as was done before the war. It is the duty of the Navy to take the responsibility for the maintenance and strengthening of shipping.

Arms: In view of the present situation under which the supply of various kinds of arms is very difficult, increased production required by the projected expansion of naval strength cannot be achieved unless every possible means is taken and utmost effort are exerted. It is especially true in the case of air arms The productive capacity for fuel is expected to be increased to approximately 70 percent of present requirements.

Facilities: In view of the recent shortage of labor and materials, it is evident that the nation's production capacity is reaching its maximum. Consequently, in order to meet production requirements, it is imperative to further study the priority system.

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Materials: For the execution of this program, a shortage of 300,000 to 400,000 tons in the annual quota of steel as well as a considerable shortage in aluminum is expected. The situation in regard to other special metals is also expected to worsen. Therefore, the Navy must plan an allotment increase in the material mobilization quota and the nation must expedite the development of resources for these materials and increase their production.

Transportation: As a result of the proposed expansion of armament and extension of operational lines, increase in transportation capacity would inevitably be required. However, present conditions make it impossible to meet these requirements. Unless these difficulties can be surmounted, the expansion of armament and preparations for war will be hindered to a considerable degree.

Military men: According to the program, the fixed number of commissioned personnel at the end of fiscal year 1947 is estimated at approximately 760,000 and that of the wartime personnel at approximately one million. The annual minimum number of the required conscripts is estimated at 150,000. However, according to the number of personnel to be allotted to the Navy, determined by the recent agreement between the Army and Navy, there will be an annual shortage of approximately 40,000. Consequently, it calls for further consideration by Army and Navy authorities.

Laborers: It is estimated that the total number of laborers required during the fiscal year 1947 will be more than 2,600,000 (at present it is estimated to be 1,600,000), inclusive of laborers

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required by plants outside the Navy's direct control. Moreover, when the estimated average loss of laborers which at 10 percent, is taken into consideration, a further 300,000 to 350,000 laborers will be repaired each year. However, the annual allotment of conscript laborers expected by the Navy ranges at the most between 200,000 to 250,000. Such being the case, the shortage of laborers must be compensated for by the utmost utilization of Koreans, Formosans, prisoners of war and inhabitants on the spot, as well as by the reduction of personnel in charge of administrative affairs and by improving efficiency.

Expenses: Roughly estimated expenses necessary for the execution of the established armament and war preparation plans, as well as the existing plans, are as follows: (in 100 million yen)

Fiscal Year

1943

1944

1945

1946

1947

Organizational expenses

102

95

91

88

74

Maintenance expenses

26

38

49

59

70

Total

128

133

140

147

144

As the Army expenses required approximately the same amount, it became necessary to float loans to raise the money.

Conclusion: In view of the urgency of the situation, important items in this plan will be initiated. However, in view of the fact that there are many difficulties to be surmounted in order to accomplish Naval General Staff's Plan, utmost efforts will have to be made to realize it by adopting the priority system and by adjusting the relations between various departments to the fullest extent.

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At the same time, in order to accomplish the proposed expansion of air strength (inclusive of aircraft carriers, communications and arms for aircraft, as well as many other items related to aircraft), it is necessary to prepare a plan to abandon, or postpone, the maintenance of other strength. Furthermore, it will be necessary to take various measures to give priority to the Navy with reference to the allocation of personnel and materials.

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