JAPANESE MONOGRAPH NO. 85

Preparations for Operations in Defense of The Homeland, Jul. 1944 - Jul 1945

PREFACE

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, charged 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.)

PREPARATIONS FOR THE COUNTERATTACK AGAINST THE ENEMY INVASION OF THE HOMELAND

PREPARATIONS FOR THE COUNTERATTACK AGAINST ENEMY LANDINGS ON THE HOMELAND

Chap. I. Changes In the War Situation and the Decisive Battle for the HOMELAND.

A. The Initial Preparations for the Decisive Battle for the HOMELAND.

After the war progressed into the 3rd phase of operations in the spring of 1943, every attempt to counterattack the enemy has been forestalled. With the exhaustion of national resources and the dwindling of our fighting strength, the situation has gradually mads a change for the worse.

With the fall of the MARIANAS on 8 July, 1944, following the enemy capitulation on SAIPAN, GUAM and TINIAN, the seas around the MARIANAS were ruled by the ALLIED Powers.

Their fleet was in such a position as to be capable of attacking our HOMELAND directly if the situation demanded.

This being the case, we decided to conduct a decisive operation with our last defenses extending along a line running from the HOMELAND to the PHILIPPINES.

In July of that year Operational Plan "SHO" was issued and its preparations were expedited.

On 21 July, the immediate task of the Combined Fleet (Imp. GHQ Navy Section Order No. 431) was issued as a part of the "SHO" Operational Plan. As a result, various problems concerning the all-out battle on the HOMELAND inevitably came to the surface. With the MARIANAS SEA in the enemy hands, the Naval and Guard Dist. Units, which had been regarded as "inner line" units, now found themselves in the same position as the "outer line" units.

In the light of the general situation, it was considered quite probable that the next offensive of the ALLIED Powers would be directed against the PHILIPPINES or the OKINAWA ISLANDS. Due to a lack of transportation facilities for war materials for the preparations of Operation "SHO", preference was laid on strengthening the defenses in the OKINAWA and PHILIPPINE ISLANDS where enemy attacks were considered most probable. Consequently, preparations in the HOMELAND Area were not completely carried out and were effective only in the case of the possibility of imminent danger from a major invasion.

The preparation for Operation "SHO" permitted an opportunity to slightly strengthen our defenses in the HOMELAND, where as previously all of our efforts had been concentrated upon air defense. At any rate, the distinction between the "inner line" Naval Dist. and Naval Guard Dist. Units and the "outer line"

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fleets was gradually eliminated.

3. The Naval and Guard Dist. Units were Placed Under the Tactical Command of the Cmdr. in Chief of the Combined Fleet.

With the elimination of the distinction between the "inner line" and "outer line" units, the old chain of command in which the commanders of the Naval and Guard Dist. Units were not under the Cmdr. in Chief of the Combined fleet, made operations by the Combined Fleet which constituted the main body for our AMERICAN and BRITISH Operations very complicated.

In January 1945, the CHINA Area Fleet, units under the command of the Surface Escort Units Hq. and the Naval and Guard Dist. Units, insofar as Operation "SHO" was concerned were placed under the tactical command of the Cmdr. in Chief of the Combined Fleet. The entire Navy, thus, by consolidating its sea and air operations under the unified command of the Cmdr. in Chief of the Combined Fleet, was in a position to participate in the impending Operation "SHO".

Later in April the Naval Guard Hq. was established and under its commander all of the Naval Units except for the SOUTHEAST and SOUTHWEST Area Fleets, which had practically been isolated, were completely consolidated. C. Map Strategy in Imp. GHQ.

At the beginning of March 1945, a study of map strategy concerning a supposed enemy landing in the KANTO Dist. was carried out by the personnel of the Navy and Army Supreme Commands.

This study made our dismal future evident, as previous operations had not been favorable. Although this strategy was carried out to a certain extent in order to orient the Naval and Army personnel with the fact that the Army would take the leading part, it had an adverse effect in that concern was aroused as to the defenses for the decisive battle on the HOMELAND.

As a result, frequent negotiations were held between the Army and Navy concerning the assignment of operational missions as well as the operational principles and preparations.

The Imperial GHQ Navy Section Order No. 37 issued in January 1945, defining the operational principles for the Cmdr. in Chief of the Combined Fleet, constituted the basic for executing the Naval Operations when the decisive battle on the HOMELAND took place.

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In view of the unfavorable results of the map strategy, the necessary agreements were gradually concluded between the Navy and Army regarding the HOMELAND Operation, thereby forming a definite policy for Operation "KETSU".

The difficulty of carrying out a decisive battle on the HOMELAND was recognised as the important factor characterizing Operation "KETSU". All national resources, manpower and material were vital in carrying out this operation.

Due to this necessity, some staff members began to believe that it would be best to reserve all national resources for operation "KETSU". This opinion predominant in the Army, tended to diminish the importance of the OKINAWA Operation. To combat this, the Navy revealed its resolution to concentrate its entire strength in the SEINAN ISLANDS (OKINAWA ISLANDS) Area Operation prior to the enemy invasion on that area. Furthermore, the Navy stressed the necessity of accelerating the operational preparations in the KANTO and KYUSHU Districts.

D. OKINAWA Operation and Preparations for Operation "KETSU".

At the end of March, when the ALLIED Forces invaded the OKINAWA Area, the Navy enforced the OKINAWA Operation by throwing in all available strength. The Army also poured a fairly powerful air force into the operation beside its garrison forces in that area.

As the battle in that area progressed against us, the immediate completion of the preparations for Operation "KETSU" became more urgent. Since the Army still retained large number of ground forces in the HOMELAND, it was its duty to strive to complete this preparation. This attitude, however, was apt to be regarded as an indication of a letdown of determination to fight the OKINAWA Operation to its conclusion, which operation was in full swing at the time. Consequently, this brought about various contradictory issues between the groups in favor of continuing Operation "TEN" (Navy) and those desiring to prepare for Operation "KETSU" (Army).

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Chap. II. Estimate of the Situation of the Possibility of Invasion by the ALLIED Forces.

Although in Hay 1945, the OKINAWA Operation was still in full swing, the final outcome was already evident. The probable subsequent attempts of the ALLIED Forces were carefully re-examined, resulting in the following conclusions.

A. Estimate of the ALLIED Force. (As of May 1945).

1. Estimate of the Operational Plan of the ALLIED Powers.

a. The evaluation in the UNITED STATES resulted in the opinion that although that country had suffered heavy losses both in material and morale it would be able to carry the war to JAPAN without assistance from its ALLIES by utilising its abundant natural resources, and redeploying troops which were previously to be used against GERMANY. BRITAIN would probably welcome an early termination of the war following the defeat of GERMANY. However, she would have little to say as to the general situation view of the strong position of the U.S.A. in the war against JAPAN. Because of the necessity for cooperation with AMERICA, and in order to strengthen her position at the peace table, BRITAIN was estimated to be reinforcing her forces in the FAR EAST as well as increasing her efforts to finish the war with JAPAN.

CHINA, having been kept in check by the civil war with the REDS in YUNAN and by the ambiguous attitude of the U.S.S.R., still attached importance to cooperation with the U.S.A. With a view to completing the war with JAPAN and improving her international position, she would probably open an active counterattack campaign.

As estimated above, these three powers were not necessarily in accord in their war purposes. Moreover, there were differences in their fighting spirit varying with the conditions in their countries. For the present however, since the circumstances demanded mutual cooperation it was thought highly improbable that they would divide against each other.

If, however, JAPAN succeeded in carrying out a long and protracted war, inflicting severe losses on the ALLIED Force, and thereby shaking their will to continue the war, there would probably be an opportunity for an advantageous peace talk.

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b. The U.S.S.R. had been readjusting her diplomatic altitude so as to wage war against JAPAN whan the prospect of the future of the EUROPEAN War was evident, together with the strengthening of her armament in the FAR EAST to increase political pressure upon JAPAN. For this reason it was highly possible that the U.S.S.R, would try to achieve her long cherished ambition by talcing arms against us when it was decided that conditions were in her favor. Judging from the redeployment of her forces, the time was estimated to be after August.

2. Estimate of the Strength of the Allied Powers to be Used in Their Offensives Against JAPAN.

a. Sea Strength. (1945).

Type of ship.

Aircraft carriers

a A (T.N. ?)

Battleships

Cruisers

Destroyers

End of July

25/28

70/85

23/23

35/64

244/324

End of

26/28

74/89

24/24

36/64

254/331

REMARKS:

1. These figures were obtained in consideration of the results of the OKINAWA Operation and from the numbers released by U.S. at the end of April, (the above figures denotes ships capable of being put into action against JAPAN.

Botton figures denote total ships).

2. About half of the ships damaged in Operation "TEN" were believed to have been repaired and put back into action by the end of Feb. or Mar. and half of the remaining ships by the end of Mar. or April.

3. The new aircraft carriers, ANTIETAM, TARAWA, and BOXER were estimated to be capable of being put into action by the end of June, July, and August respectively. The SARATOGA and RANGER, as trainers, were not included in this table.

NOTE:

1. In addition to the ships in the table, the BRITISH Fleet, consisting of approx. six battleships, four aircraft carriers and eight aircraft carriers as its main force should be taken into consideration as a potential participants in the attack.

2. It should also be taken into account that the sea power could be concentrated in any attack if necessary.

b. Air Strength (1945)

AREAS

End of July

End of August

End of September

NORTH

ALASKA

400

400

400

ALEUTIAN

300

300

300

CENTRAL PACIFIC

ELIS, GILBERT, SAMOA Dists.

150

150

150

MARSHALL

200

20

200

MARIANA

1,000

1,000

1,000

PELELIU, WULCY

250

250

250

IWO JIMA

500

500

500

HAWAII

900

1,900

1,900

TRANSPORTS

200

900

200

PHILIPPINES

3100

4100

5100

SOUTH WESTERN ISLAND

600

650

870

NEW GUINEA and AUSTRALIA Area

EAST NEW GUINEA

300

300

300

WEST NEW GUINEA

600

600

600

AUSTRALIA

250

250

250

SOUTH PACIFIC

SOLOMONS

200

200

NEW CALEDONIA, ESPIRITU SANTO

300

300

300

FIJI

100

100

100

NEW ZEALAND

100

100

100

INDIA-BURMA Area

1500

2000

2000

CHINA

U.S. Air Force

700

800

800

U.S., CHINESE Air Force

150

150

150

Transports between INDIA and CHINA Air Fleet

400

400

400

Air Fleet

3,700

3800

3800

TOTAL

16000

17850

19370

NOTE:

(1) About the end of July, a part of the EUROPEAN Forces is expected.

(2) The expected ALLIED Air strength for the HOMELAND Operation is classified in the attached list.

c. The Ground Strength (1945)

DIVISIONS

July

August

ARMY

Inf. Div.

53/90

70/90

Armored Div.

7/22

10/22

Airborne Dir.

3/10

4/10

Cavalry Div.

1/2

1/2

TOTAL

64/134

85/134

Marine Div.

7/10

8/10

TOTAL

73/144

95/144

EXPLANATION: 1. The estimation of this list is calculated with the following supposition.

(a). After May, two divisions will be dispatched for the JAPANESE Operation every month.

(b). About one half of the force of approx. 60 divisions on the WESTERN FRONT of EUROPE will be diverted for the JAPANESE War as follow:

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Strength (No. of Div.)

Departure from Europe

Arrival in PHILIPPINES

Completion of Operational Preparation

Order of Movement

1st Movement

About 10

Middle or latter part of May.

By the end of July.

End of August.

2nd Movement

About 20

June

By the end of August_

End of September

(Note) The necessary materials and munition for the operation will be transported directly to the PHILIPPINES from the U.S.

2. The lower figures in the above list show the strength of such month and the above figures show approx. the strength to be used for the JAPANESE Operation.

(Remarks)

a. The expected strength to be used in the following Invasion points (July).

KOREA: - 6 - 10 Div.

SOUTHERN KYUSHU: - 16 - 20 Div.

SOUTHERN SEA Coast of SHIKOKU: - Less than 10 Div.

B. The expected strength to be used in the following invasion points after September.

SOUTHERN KYUSHU: - 15 - 20 Div.

KANTO (TOKYO Dist.): - 30 - 40 Div.

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Date\Area

MARIANAS

IWO JIMA

SOUTH WESTERN ISLAND

PHILIPPINES

B29 x 50

B29 x 50

About 500

P47

x 300

Fighter x 1500

(fc)

B29 x 3001 included B17, B24 added 70

B17, B24

2550

End of July

Others

B24 x 150

P51

P51 x 250

P61

Bombers x 1000

P61 x 30

Carrier borne plane x 100

600

Others x 10

Others x 50

B24 x 150

PV x 30

Flying boat x 40

End of August

Same as

above

Same as above B24 may be used instead of B29

P47

300

650

Fighter x 2000 (fc)

B29 x 400 included others* same as above

4100

P51

P61

Bombers x 2000,

(Fb)

Carrier borne plane x 100

B24 x 200

Others x 100

PV x 30

Plying boat x 40

End of Sept.

Same as

above

Same as above

P47

x 400 1

870

fc x 2,500

B29 x 500 included. others same

as above

5100

P51

P61

Carrier borne plane x 100

fb 2000

B24 x 300

PV x 30

Others x 100

Flying boat x 40

3. Anticipated Advance Points and Landing Points and Time for Invasion by the ALLIED Forces.

a. Anticipated Landing Points and Time of the Enemy Invasion.

In view of the fact that the enemy had landed on the OKINAWA ISLANDS with the intention of achieving an early termination of the war by advancing step by step to our vital area around TOKYO. It was estimated as being quite probable that they would attempt primarily to invade the SOUTHERN KYUSHU and SHIKOKU Area, and establishing air and naval Bases there, would watch for an opportunity to capture the KANTO Dist.

Particulars of this estimate were as follows:

1). There was great probability that the enemy would expand its operations to TOKUNOSHIMA, KIKAIGASHIMA, ATSUMI (TN AMAMI?) OSHIMA etc. upon completion of their operation in the OKINAWA Area, probably in June 1946.

2). By strengthening the air forces in the OKINAWA, IWO JIMA and MARIANAS Areas, they would probably redouble their already devastating air raids upon the HOMELAND from about June 1946 in order to break down our national power, our will to continue the war and to destroy our air strength. It was almost certain

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that, 1a unison with these actions, the enemy submarine-warfare would be intensified to paralyse our sea transportation.

3). Their invasion of KOREA would not be possible unless changes took place in the relationship between the U.S.S.R, and U.S.A. However,

it was possible that they would invade the SAISHOTO Area to cut off the JAPAN-KOREA transportation and also to advance their base for attacking the HOMELAND. The time should be approx. July or August of 1945, and if no landing took place during that period, there would be no such attempts.

4) . Probably no major invasion would be carried out on the KYUSHU and SHIKOKU Areas before July or August, due to the preparations for this air operation and the readjustment of their task force. Landing on the KANTO Dist. would be effected after Sept. in view of the state of rearrangement of their ground forces.

b. Anticipated Landing Points and Advance Routes.

1).  Concentration Bases of Invasion Forces.

Navy: WULCY or LEYTE BAY by the main force.

MANILA and OKINAWA by an element.

Army: The PHILIPPINES by the main force and OKINAWA ISLANDS, an element.

(In the case of an invasion of the KANTO Dist., the MARIANAS might be used by an element).

2). Anticipated Advance Routes.

a). Intercepting the transportation between JAPAN PROPER and CHINA Continent, they would probably attempt to advance to the HOMELAND. In this case, the landing points should be first of all in KYUSHU, and then in the KANTO Dist.

b). While preparing for the invasion of the HOMELAND, they would probably first aim at SAISHOTO and other strategic points surrounding the EAST CHINA SEA. Furthermore, if the situation demanded, they might occupy some key points in CENTRAL and NORTH CHINA. Thus, cutting off the liaison between JAPAN, CHINA and MANCHURIA and by pushing forth their air bases for attacking the HOMELAND, they would probably attempt to neutralise the JAPANESE War effort and when this proved insufficient, would launch a major landing operation on the KANTO Dist.

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3). Landing Points.

a). KYUSHU Dist.

SOUTHERN part of the WEST Coast of KYUSHU to the NORTH of KAMESHIMA and NOMA POINT. (An element). ARIAKE BAY and the SOUTHERN Part of the EAST Coast of KYUSHU to the SOUTH of MIYAZAKI. (Main fores).

b). SOUTHERN Coast of SHIKOKU.

Sea shores near SUZAKI.

c). KANTO Dist.

OSHIMA TATEYAMA BEACH, KUJUKURI BEACH and KASHIMANADA, especially the vicinity of CHOSHU. (An element). Coastal areas of SAGAMI BAY.

Note: It was also expected that they would probably land reinforcements on some strategic points in the TOKYO BAY Area when the invasion had progressed to a certain degree.

e. Estimate of the Operational Plans for Invasion by the ALLIED Powers.

1). Operational Plan for the Landing on KYUSHU.

a) . By swiftly establishing air bases in the OKINAWA Area and distributing powerful land based air units there, they would probably launch mass raids, mainly an areas west of CENTRAL JAPAN to smash our air strength and to disintegrate our sea and land transportation. In collaboration with these attacks, large type bombers from the bases on IWO JIMA and the MARIANAS would probably carry out thorough air raids on the entire HOMELAND to weaken our national power as well as our fighting spirit and to keep in check the transfer of our air forces to the KYUSHU Area.

b). Prior to the commencement of the landing operation, their task force would probably launch mass air raids to neutralize our main air base groups and bases for special attack planes. (It would be possible to conclude their potential landing location by studying this attack by the task force).

c) . There was a great probability of their landing possibly with one division, prior to their main operation on KAMESHIMA to establish a boat staging base. The enemy task force was expected to support this operation with its main force from the sea east of the HOMELAND, and with an element from the SOUTH.

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d) . Their invasion would probably begin on the SOUTHERN part of the WEST Coast of KYUSHU several days after the establishment of a amphibious base on KAMESHIMA. In order to accelerate its progress, this landing would probably be carried out directly from transports and also from landing barges in which the troops were to embark behind KAMESHIMA. The enemy strength for

this action was estimated at three divisions for the first and second landings respectively and to be completed in general within a week. During this operation, besides many escort carriers, their task forces were expected to directly support the landing troops.

e) . After having established a bridgehead at the SOUTHERN part of the VEST Coast of KYUSHU, the enemy would probably effect another invasion on the SOUTHERN part of the EAST Coast. The strength was expected to be over six divisions with their rear units landing in ARIAKE BAY.

f) . The invasion troops on both the EAST and WEST Coasts would probably advance swiftly in an effort to establish contact, and their occupation of our air base group in the SOUTHERN part of KYUSHU and sea transport bases in KAGOSHIMA and ARIAKE BAYS during the afternoon of their landings was probable.

g). Due to the varying oceanic conditions according to the time of the enemy operation, it was necessary to expect considerable variations in the operational plan for their landing.

2). Operational Plan for Landing on the KANTO Dist.

a). In the event that they should begin an invasion in the KANTO Dist. without pushing their sea and air bases to KYUSHU, it seemed quite probable that they would occupy the OGASAWARA ISLANDS beforehand, probably HAHAJIMA, to gain sea and air bases there.

b). With the same intentions as estimated above regarding the probable invasion of KYUSHU, they would most likely carry out greater devastating air raids coupled with active sea operations than those in the case of the KYUSHU landing in an effort to achieve their air annihilation operation.

c). There was great probability that they would invade OSHIMA prior to the KANTO Dist.

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d). following the occupation of OSHIMA, they would probably affect a mass landing on KUJUKURI SHORE and KASHIMANADA directly from transports and landing barges. By maximum landing efficiency, a minimum of eight divisions were expected to complete their landing within a week. Simultaneously with this invasion, a diversionary operation was also probable in the TATEYAMA Dist. This landing on the EAST Coast of the BOSO PENINSULA would be backed up by the entire strength of the enemy task force off shore and by escort carriers adjacent to the coast.

a). On establishing a bridgehead on the BAST Coast of the BOSO PENINSULA, the ALLIED Forces would probably open a major landing operation by their main force on SAGAMI BAY. This was expected by a powerful force of no less than 12 divisions within seven to ten days after their landing on the EAST Coast of the BOSO PENINSULA.

f) . Vith the progress of the invasions, it was also necessary to expect the enemy fleet's to force its way into TOKYO BAY to land another invasion force.

g). Because of the topographical feature in that area, the BOSO Invasion fores was estimated to be mainly for the securing of air bases and for the diversion of our ground forces, while those on SAGAMI, to advance directly to the KANTO PLAIN.

(APPENDED SHEET).

Chap. III. Estimation of the National Power and Fighting Strength of JAPAN. (May 1945)

1. Summary.

Vith the dwindling of our fighting strength and of sea and land transportation, the production of essentials had been on the decline coupled with deepening scarcity of food stuffs. This added to the difficulty of executing modern warfare of mobilizing national resource.

At this juncture, careful attention had to be paid to the trend of popular feeling, which demanded immediate countermeasures.

2. Trend of Popular Feeling.

There was no doubt that the people would loyally resist any enemy invasion. On the other hand, a general desire that the situation improve was evident. Criticism against the military and the government grow prevalent gradually, bringing about an atmosphere in which the confidence in the leading circle was liable to be shaken. To make matters worse, there was a sign of degenerating national

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morale strong sense for self-defense and weakening of the will to serve the country. Scepticism and self-abandonment grew among the masses, even effecting the farmers. An undercurrent of fretfulness from the desire for peace was undermining the intellectuals. Taking advantage of these circumstances, some ambitions elements appeared to have been attempting a revolutionary intrigue. This being the case, should the OKINAWA Operation be lost, our most careful attention and proper guidance ought to be attached to the trend of popular feeling. Moreover, the enemy psychological warfare seemed to be growing more intense.

3. Man Power.

a. The ran power had not yet suffered greatly by the war, leaving some margin as compared with material resources. However, its usage had been inadequate.

Mobilisation and redistribution did not meet the changing state of production, resulting in maldistribution of required personnel. It was considered that if a thorough redistribution of man power was enforced, there would be no great hindrance in the execution of war insofar as man power was concerned. Moreover, if utilised adequately, there would be a margin, although insufficient for a large scale conscription of men.

b. The evil effect of the war caused a decrease in births while the lower physical standard of the people deserved special attention.

4. Transportation Facilities and Signal Communication.

a. Bus to the heavy losses by the war, our total steamer tonnage fell to one million. Because of the scarcity of fuel coupled with dwindling loading facilities and increasingly intensified enemy attacks, our sea transportation had nearly been paralyzed. If the recent rate of losses of tonnage in ships continued, our number of transports would practically dwindle to nothing by the end of this year.

Our transportation to the Continent was dependent to a great extent upon the outcome of the OKINAWA Battle, and if worst come to worst, we had to face the termination of our systematic transportation to the Continent after June.

Transportation by steam and sail driven boats was being rapidly reduced by the lack of fuel and enemy actions.

c. Due to the severe loss of cars in enemy air raids coupled with the exhaustive use of all equipment, the railroad transportation had recently dwindled. Intensified air raids on the railroad network would probably be inevitable in the near future. Tor these reason, the railroad transportation was

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expected to be reduced to half is compared with the previous year notwithstanding our all-out efforts. It was feared that this integrated schedule of railroad would be impossible in the latter part of this year.

c. Due to inadequate management system and peculiarity of labor conditions coupled with the scarcity of material and fuel, the local transportation and harbor loading constituted a serious bottleneck in the smooth execution of sea and railroad transportation. Furthermore, in view of the intensification of air raids, a stoppage of harbor functions seemed eminent.

d. Because of damages incurred by air raids and the special conditions of its material and personnel, signal communications had lost their efficiency. Moreover, the situation was expected to become grave in the latter half of this year.

5. Material.

a. Since the reduction of mining and difficulties in transporting ore and industrial coal caused the production of steel and iron to fall to about one-fourth of that of the corresponding period of the previous year, prospects of building steel ships seemed hopeless for the remaining part of this year. There were many difficulties to overcome even in the maximum utilisation for national defence of materials in the stock.

b. Vith the dwindling of production and transportation, the supply of coal to the KANTO and KANSAI Districts had dropped considerably. As a result coupled with the increasing damages by air raids, production in the industrial centers had been on the decline. The outcome of coal transportation in the latter half of this year held the key to the question as to whether the industrial centers would be paralyzed.

c. With the decrease of industrial salt from the Continent, production of the chemical industry using soda had been increasingly on the decline. It was feared that we would inevitably face a crisis in procuring industrial salt in the latter half of this year. Should this happen, not only the production of light metal and synthetic oil, but even the securing of gun powder and explosives would become nearly impossible.

d. The supply of liquid fuel was, thereafter, solely dependent upon the resources under our control within the territories of JAPAN, MANCHURIA,

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and CHINA. With the dwindling of stock, together with the delay in the progress of the plan for increasing its output, the lack of high octane gas was anticipated to seriously affect the execution of the war after the middle part of this year.

e. The production of modern weapons centered on aircraft was expected to come to a stalemate before long due to the disintegration of production and transportation by the intensified air raids and the scarcity of fuel and materials.

6. National Livelihood.

a. Vith the scarcity of food stuffs growing more serious the traditionary period of the year was the worst crisis since the outbreak of the war. Even if the scheduled imports of cereals and salt were secured, the people would be confronted with food crisis in which the minimum quantity of food stuff and salt necessary to fulfil physical requirements would be barely available. Vith the possibility of the sea and land transportations being disintegrated and of a bad harvest due to the adverse weather and enemy air raids, it was feared that starvation would take place in some localities, bringing about serious disturbances in the public peace. Furthermore, a more difficult food condition was overshadowing the already gloomy situation.

b. The recent sharp rise in commodity prices brought about rampant black marketeering. In view of the deteriorating economic structure, there was

a probability that the systematic running of war-time economy would be driven into a perilous state by the vicious inflation.

B. Fighting Strength of the Navy.

In the light of the national production capacity sinking with the fall of the PHILIPPINES and OKINAWA, our efforts were concentrated on the mass production of "underwater special attack weapons" which required only a comparatively simple process to manufacture as well as in the mobilization of planes already made. Furthermore, the mass production of special planes such as "KIKKA" and type "KI" - 115 was taken up to increase our fighting strength notwithstanding the sceptical opinions in some quarters.

Outline of the Naval strength toward August 1945 was as follows:

--15--

1. Air Strength.

Fighters

1,1701

2,826

Night Fighters

125

Light Bombers

636

Fighter Bombers

60

Carrier borne planes

310

Attack planes

266

Medium Bombers

352

Land bases attack planes

197

Land based bombers

155

5,044

Seaplanes

398

Reconnaissance

348

Flying boats

10

Sea bombers

40

SAIUN

70

Other Combat Aircraft

75

Trainers

2,218

Medium trainers

1900

SHIRAGIKU

318

2. Special Attack Weapons.

"KORYU" 100; "KAIRYU" 300; "KAITEN" 120; "SHINYO" 2,000 Note: The effectiveness of "SHINTO was restricted only to a short

perimeter due to their poor cruising range, and those capable of action in the KANTO and KYUSHU Districts were about 1,000.

3. Ships.

In view of the critical situation in the fuel at this time, surface craft were considered unimportant and in general were assigned to the air defense of Naval bases. The total remaining ships numbered four battleships (all damaged); five aircraft carriers (all partially damaged); two cruisers; 23 destroyer and 46 submarines of large, medium and small types.

Chap. IV. JAPANESE Operational Plan and Tactics.

A. JAPANESE Operational Plan.

1. General Principles.

a. By strengthening our national defense structure at any cost and also by distributing the ground and anti-air forces to key points, our efforts will be concentrated primarily on the maintenance and functioning of our production and transportation. According to circumstances, the main force of the national defense will be transferred and concentrated in appropriate localities.

b. The equipment of air and special attack bases will be swiftly improved. In doing so, particular precaution should he attached to anti-air screening so as to preserve our fighting elements for the pending decisive battle.

c. Surprise attacks on the enemy bases in the MARIANAS and OKINAWA as well as on their task force while in anchorage will be stressed in order to decrease their fighting power in the coming HOMELAND Operation.

d. Special heed will be given to the movements of the enemy task force and transports as well as to the state of their accumulation of munitions in order to discover their invasion attempt as early as possible. Thereby, we would be able to make the necessary preparations in collaboration with the Army before the landing took place. All-out efforts should be made to shatter enemy invasion force while they are enroute. In so doing, our attacks will be concentrated on the enemy transports and landing barges, although circumstances might warrant diverting our attacks to the task force and escort ships.

Preparations should be carried out so as to mobilize the entire Naval strength available to counter-attack the enemy at the very outset of invasion, and at the latest, within two weeks to advantageously influence the subsequent ground battle.

e. In this stage of the battle, special caution should be paid to avoid unnecessary aggravation of the U.S.S.R. so that we may concentrate upon the battle with the U.S.

2. The JAPANESE Operational intention was to annihilate the majority of the ALLIED Invasion Troops an the sea and in the vicinity of their landing

--17--

point so as to frustrate their invasion attempt in its initial stages. The Army had laid down an operational plan with the principle of annihilating the enemy landing troops in coastal strategical points before establishing a bridgehead. (In reference to the air operation, they had a similar principle with the Navy).

The Navy intended to smash the invasion force while still in anchorage prior to its landing by concentrating its attacks mainly on transports. For this purpose, it was planned that the majority of its available force, air, surface and underwater would attack the first convoy of enemy invasion troops upon its arrival at anchorage and within the following ten days by concentrating its attacks on transports.

3. Operational Plan of the Navy was as Follows:

a. An element each of the small and medium type submarines will patrol 200 to 300 miles from the coasts where an enemy invasion is most probable. In unison with this action, airplanes will carry out patrols in an effort to discover enemy attempts to invade. Thereby, an enemy convoy could be contacted by at least the day previous to its arrival at its destination.

b. Small and medium type submarines will be disposed in the seas around the anticipated anchorages of enemy convoys, and when an attempt to invade becomes certain, available special attack strength, surface and underwater, will be concentrated in possible enemy anchorages.

Large type submarines engaged in the interruption of the enemy lines of communication will concentrate their attacks to the rear of the invasion troops.

c. A picked element of the air force will attack the enemy task force in an effort to neutralize them even for a short period. Another element capable of night attack will also attack the U.S. Fleet which would bombard the landing point.

d. The entire strength of the remaining air force will launch a series of attacks on enemy convoys immediately after locating them. After their arrival at the anchorage, an element of the air force stated in the preceding clause will join the offensive, if the situation demands. Small and medium type submarines as well as surface and underwater special attack forces will likewise strive to destroy the enemy convoy.

e. The majority of the air and special attack forces will be used in recurrent attacks on the convoy preferably within ten days after its arrival.

--18--

Measures should be taken to concentrate as much strength as possible in the initial phase of the attack.

f. In case an enemy convoy approaches the coast of KYUSHU north of ARIAKE BAY or the south and west coasts of SHIKOKU, the full strength of the surface units which is concealed in the western part of the SETO INLAND SEA will set forth to attack the convoy by night.

g. Whan an enemy landing attempt becomes certain, an element of the air borne raiding units will immediately attack the U.S. air bases which are most likely in a position capable of supporting the landing. Those bases could be temporarily neutralised, enabling our air force to execute its operation without serious opposition.

B. Details of Using Various Units of the Navy.

1. Usage of Air Units.

a. Principle.

The principle to be followed in using our air force in Operation "KETSU" was to destroy enemy convoys at sea by combining the entire Army and Nary Air Forces in the initial stage of their invasion.

b. Smashing of the U.S. Invasion Convoy.

1) . Airplanes and submarines will carry out reconnaissances from the HOMELAND, the islands south of JAPAN, FORMOSA, and the NETHERLAND INDIES on the U.S. advanced bases and on the open seas. Likewise, a total of approx. 140 planes including "SAIUNS", land based planes; and flying boats will carry out day and night patrols over the seas within a 600 nautical miles perimeter from the HOMELAND for the early discovery of enemy convoys, at the latest by the day prior to their arrival at the destination.

2) . Series of attacks will be enforced day and night by mobilizing the full strength available on enemy convoys in the initial phase of their invasion, within ten days following the arrival of their first convoy at anchorage. Their the convoys could be destroyed prior to or immediately after their arrival at anchorage.

3). These offensives will be carried out mainly by employing suicidal special attack planes according to the following schedule)

--19--

OBJECT

FORCE TO BE USED

Enemy convoys in the open sea prior to their arrival at destination

Naval combat aircraft for special attack:

825

Convoys just prior to and after their arrival at anchorage.

1. Army planes (Inclusive of special attack planes):

Approx. 2,500

2. Naval trainers for special attack:

2,900.

4). In case of an invasion, one half of the invading troops was expected to be coped with at sea by the above scheduled attacks. (The remaining half could be annihilated by the Army).

5). Approx. 2,000 Army and Navy fighters will strive to gain command of the air to facilitate the attacks of our special attack forces.

Furthermore, if the situation demands, the fighters will straff and bomb enemy landing barges and transports.

c. Attacks on the U.S. Task Force.

1). Emphasis will be placed on the attacks against enemy transports, assigning a minimum strength to those on the U.S. Task force. For the preservation of air strength, our air force will not attack if the enemy invasion is uncertain, or even if an enemy task force should attack the HOMELAND unless positive of achieving their mission without serious losses.

2). When the enemy invasion becomes certain, a highly trained element of the Air force (approx. 330 Naval combat craft for the special attack) will launch offensives on the U.S. Task Force to temporarily prevent it from supporting their convoy.

d. Attacks on the Main Air Bases of the U.S. Force.

1). When an attempt of the U.S. Force to invade the HOMELAND becomes obvious, our air borne raiding force will attack U.S. Air Bases to temporarily neutralize those which are considered in the most favorable position to support their invasion force.

2). To achieve this end, an air-borne raiding unit will be organized with approx. 100 transport planes and 1,200 personnel to prepare for forced landings at several enemy air bases in the OKINAWA Area. (The first Invasion Point of the U.S. Force was anticipated to be on KYUSHU or SHIKOKU).

--20--

e. Attacks on the Enemy Ships Assigned to Bombardment of Landing Location.

1). Prior to the enemy landing night attacks will be carried out by our well-trained force consisting of approx. 50 land attack planes, 50 seaplane bombers, and 50 carrier attack planes upon escort ships to decrease their fire power.

With the development of ground operations, our targets will be shifted from enemy transports to escort ships to facilitate the Army operation.

f. Direct Cooperation with the Ground Battle.

Cooperation in the ground battle by the Army and Navy air forces will as a rule not be considered except for attacks upon enemy escort.

g. Distribution of Forces.

1). Based on the estimate of the first invasion of JAPAN PROPER by the U.S. Fores to be at KYUSHU or SHIKOKU and to take place after September, in the WESTERN Part of the HOMELAND, completing its deployment by the middle of August.

2). Taking into consideration the possibility of an invasion in the KANTO Dist., the main point of concentration will be gradually shifted to the WESTERN Part of the HOMELAND any time after September 1945.

3). Schedule of the Disposition and Use of the Army Air Force:

Attached Sketch No. 1.

h. Collaboration of Command.

1). Cooperation between the Navy and Army was the main principle. During operation, the High Commands of the Army and Navy air forces were to be located at the same place or at adjacent places in order to consolidate the commands.

2). Chains of Command of the Army and Navy were as follows:

The Army

Cmdr. of General A.A.F.

Cmdr. of 1st A.A.F./1st A.A.F.

Cmdr. of 5th A.A.F./5th A.A.F.

Cmdr. of 6th A.A.F./6th A.A.F.

 

--21--

The Navy

Cmdr. of Navy GHQ

Cmdr. of 5th Air Fleet/5th Air Fleet.

Cmdr. of 3rd Air Fleet/3rd Air Fleet

Cmdr. of 10th Air Fleet/10th Air Fleet

Navy Forces during operation were as follows:

ARMY

NAVY

REMARKS

G.A.A.F., TAICHO

Naval GHQ. YAMATO

20 minutes by auto.

6th A.A.F., OITA

5th Air Fleet, OITA

Same place

1st A.A.F., TOKYO (TAKASAKI)

10th Air Fleet. YOKOSUKA

By phone.

5th A.A.F., SEOUL

3rd Air Fleet. YAMATO

2. Usage of Forces Afloat.

a. Surface Units.

1). Principle of Usage.

With the fall of OKINAWA, the enemy maintained superiority of the sea and air around JAPAN PROPER, causing great difficulty in the preservation and usage of our surface vessels.

As far as fuel was concerned, we were literally scraping the bottom of the barrel. Preservation of the surface strength until the decisive battle on the HOMELAND was inevitably decided upon as the principle.

2). Disposition of Units.

31st Destroyer Sqdn. Flag ship, the KAGETSU.
(Disposed in the WESTERN Part of SETO INLAND SEA).

17th Destroyer Gp. (three destroyers)

41st Destroyer Gp. (Four destroyers)

43rd Destroyer Gp. (six destroyers)

52nd Destroyer Gp. (Six destroyers)

3). Operational Principle.

a) . Ships will be screened from the air by utilising small islands and promontories to the north of the ITO SEA in the west INLAND SEA.

b) . With the intention of attacking enemy convoys in unison with the air force only when they are within range of a night attack, the operational area was scheduled within a 110 nautical mile perimeter from IWAI ISLAND in the WEST SETO INLAND SEA.

--22--

c). Tactics

Each destroyer will be equipped with one or two "KAITENS" (Human Torpedo) and eight "KITAGAMIS". After discharging "KAITENS" against enemy ships from as near as possible, the surface units will attack transports during the night.

d). Fuel.

Fuel will be stored in the KURE Area for the total strength to engage in 1.5 battles.

(1). The 11th Sqdn. had been organized with new surface vessels and was training in the MAIZURU Area. Due to the lack of fuel, however, it was difficult to insert them in the battle order.

(2). Escort ships were mainly distributed in the JAPAN SEA Area, for the mission of protecting sea transportation between MAIZURU, OMINATO, HOKKAIDO and NORTH KOREA. They were not capable of waging battle with any major force.

(3). In the YOKOSUKA and SASEBO Areas there were no ships capable of counterattacking enemy warships.

The NAGATO was stranded in YOKOSUKA due to the fact that the fuel supply was insufficient.

e). Submarines.

(1). Remaining Ships and Schedule for their Action.

Type and Number

Assigned Task

Special large type,

4

Surprise attacks on the anchorages of enemy fleets.

Large type,

13

Attacks on enemy supply routes and fleets with "KAITENS".

Medium type,

4

Attacks on enemy ships supporting invasion.

Small type,

9

"

Small type,

8

Patrols in the seas near the HOMELAND.

Large type,

1

Mainly for transporting of fuel for planes

Small type,

2

(2). Operational Principle.

The submarine warfare by the large type crafts will be directed mainly against enemy sea lanes between the MARSHALLS, MARIANAS, PHILIPPINES and OKINAWA. An accumulative result should be stressed by steady operations. In case an invasion should take place on the HOMELAND, its operational aims will be shifted to the invasion supply routes.

--23--

Of the medium and small types of submarines to be used in the HOMELAND Operation, the ones for patrol will undertake their task in the seas estimated to be the enemy advance route and within a 200 to 300 nautical miles radius of JAPAN PROPER: and those to attack directly will be ready for action in the INLAND SEA. If the situation demands, an element will be in the KANTO Area. Should an invasion be foreseen, they are to be immediately sent to strike the enemy before they land.

Thereafter, they will strive to persistently attack enemy transports carrying reinforcements and supplies. The submarine with planes aboard for transporting munitions and attacking hostile fleets will carry on their duties.

c). Naval Ground District Units.

(1). The entire ground units of the Navy will be placed under the tactical command of the Army during operation.

(2). Sectors garrisoned mainly by Naval forces and their strength were as follows:

SECTOR

STRENGTH

MIURA PENINSULA

12 Bns. (approx. 20,000 personnel)

KURE Naval Base Area

6 Bns. (approx. 10,000 personnel)

SASEBO Naval Base Area

10 Bns. (approx. 16,000 personnel)

MAIZURU Naval Base Area

6 Bns. (approx. 10,000 personnel)

SHIMOKITA PENINSULA

6 Bns. (approx. 9,000 personnel)

CHINKAI Naval Guard District

3 Bns. (approx. 3,000 personnel)

SOUTHWESTERN Dist. of SHIKOKU

6 Bns. (approx. 10,000 personnel)

d). Special Attack Units, other than the Air Force.

(1). Disposition of Strength. Refer to the attached sheet No. 3 and the attached sketch.

Main points for concentrating forces were in the SOUTHERN Part of KYUSHU, (The HYUGANADA -SEA- , ARIAKE BAY, and WESTERN Coast of KAGOSHIMA BAY and SATSUMA PENINSULA), in the SOUTHERN Districts of SHIKOKU, and in the KANTO Dist. (the SAGAMINADA -SEA- , mouth of TOKYO BAY, SURUGA BAY, and SOUTHEASTERN Coast of BOSO PENINSULA). The dispositions were scheduled to bo completed by the end of August 1945 in the KYUSHU and SHIKOKU Areas and by 10 Oct. in the KANTO Dist.

--24--

It was also planned that a surplus strength would be extracted from the main concentration points and redistributed to ISHIMAKI BAY, to the ENSHUNADAI (SEA) (Including ISE BAY), to the KII and BUNGO CHANNELS, and to the TSUSHIMA STRAITS.

Units and weapons to be readied for action after October were scheduled to be distributed according to the situations. With the KANTO Dist. as the most probable little field, preparations were carried out on this supposition.

There are no details available as to the outcome of the force distribution, however, the units shown in the attached sheet No. 3, which clarifies particulars of a deployment order issued on 27 July, 1945, are presumed to have finished their deployment toward 15 Aug.

According to investigations conducted at the beginning of September, the weapons of Special Attack Units had been spoiled to a fairly large extent due to improper disposal and custody at the termination of the war.

b). Usage of Strength.

The chain of command of their units is as shown in the Attached Sheet Ho. 4.

Due to the poor maneuverability of the Special Attack Unit, it was unable to move swiftly to distant localities according to the demand of circumstances, hence the determination of its assigning sectors was of great importance. Because of their relatively large mobility, however, the majority Of (pocket submarines) the "KORYUS", which had been concentrated mainly in the KYUSHU Area toward August 1945, were to be reassembled in the KANTO Dist. if the situation demanded.

Although their tactical use differed with each individual characteristic the fundamental principle of their usage was to surprise attack in mass.

Enemy troop transports were to be their primary target except for KAITENS which, having an immense striking power, were to attack battleships and cruisers escorting enemy convoys.

Their attacks were to be launched prior to or immediately after the enemy arrival at their landing point, taking into account some deviations from the set program.

--25--

Cooperation with other forces, especially with the Air Special Attack Units was encouraged to add to the battle results.

Operational program for their use was as follows:

Air patrols in search of the enemy will he widely carried out. Reconnaissance seaplanes will be attached to surface and under-water special attack unit for the sake of illuminating and revealing the enemy location. At the same time, many look-out posts will be established at coastal key points where signal communication equipment will also be installed to secure constant contact with special attack units.

If the situation demands, special attack units will prepare for action, or rush an element to probable battle areas on the seas, and on finding enemy convoys will converge the maximum strength on that location.

In this case, "KORYUS", utilising their relatively large maneuverability, will contact and strike the enemy prior to their arrival at anchorage, and thereafter will carry on attacks in collaboration with "KAIRYUS".

"KAITENS" will be chiefly used against enemy escort ships which will bombard our strategic installations or their landing points, and will also be used in coordination with other units, against enemy convoys entering anchorage.

The main operational mission of "SHINYOS" will be to attack at night the hostile transports at anchorage. Past experiences in battle proved that the "KAITEN" would have little or no chance of succeeding. However, there remained hope for success if they were properly used in unison with Special Air Attack Units under cover of smoke screens, utilizing mass raids and Surprise Attack tactics.

The principle operational mission of these forces will be to shatter the enemy invaders at sea prior to landing. However, should the enemy secure a bridgehead, their efforts will be concentrated on the interruption of enemy reinforcement routes. In addition to the tactics stated above, there would be other characteristic uses of these forces according to the strength to be utilized; geographical features, weather, and the state of the sea. At the time of the termination of the war, these Special Attack Units were only capable of practicing rudimentary tactics due to in adequate maintenance of their bases and

--26--

improper use of the weapons. It was expected that by October they would overcome such difficulties and become capable of practicing advanced tactics with more effect.

c). Operational Plan and Tactics in the Case of a Successful Landing by the Enemy.

(1) . Should the ALLIED Forces succeed in establishing a bridgehead, the battle would inevitably enter the second phase in which

a decisive battle was to be fought around the landing points, necessitating the mobilisation of all the available ground forces, and cooperation from the people. If this should fail, a prolonged resistance was to be enforced by persistent guerilla tactics even when systematic control were lost.

Particulars of the land operational plans will be stated in the reports from the Army.

(2) . By gathering all available forces, the Navy planned to continue its efforts to shatter enemy transports expected to carry reinforcements. To achieve this purpose measures were prepared for prolonged security of main special attack bases.

(3). The usage of surface and under-water forces for this period war as stated above, while that of the air force was planned for attacks on the U.S. Air Bases to be constructed on the HOMELAND and also in the rear of enemy lines of communication by reassembling remnants of our air force in the interior. This plan, however had no concrete form, and the details were to be decided upon later according to. the future aspects of battle, especially in the light of available air strength.

(4). Expected Outcome of Enemy Landing Operations.

(a). Forecast of the Outcome in the Case of an Invasion About August or September.

Total of transports anticipated:

Transports expected possible to be destroyed at sea: Approx. 470 (24% of the total).

Bases of Calculation.

-1-. Of the air force combat craft which were scheduled mainly for attacks on enemy warships and 60% of the total combat

--27--

craft (2,200) were supposed to attack enemy transports. If the ratio of success were set at 1:6, the result would be about 210 transports.

-2-. Loss of surface and under-water special attack forces was expected to be ten percent and the probability of success was estimated at 2:3 for "KORYUS", 1:3 for "KAITENS" and "KAIRYUS" and 1:10 for "SHINYOS". The results would be about 60 ships by "KORYUS", 120 by "KAIRYUS" and "KAITENS", and 90 by "SHINYOS", or a total of approx. 260 transports.

(b). If the time of invasion was postponed, the results might, at first sight, seem to be increased due to the progress in the preparation of the under-water special attack force. However, when viewed in the light of their dwindling production of munitions and of the alarming scarcity of liquid oil caused by the increase in deadly air raids, the delay of the enemy invasion was not necessarily advantageous. The problem as to whether the level of producing airplane gasoline 30,000 tons per month could be maintained after September held the key to increasing our air strength.

--28--

Chap. V. Army-Navy Relations.

A. Chain of Command of the Army and the Navy was as Follows:

Imp. GHQ

Army Section

Cmdr. of 5th Area Army

Navy Section

1st Gen. Army

" " 2nd " "

" " 17th Area Army

" " Gen. A.A.F.

" " Naval GHQ

Cmdrs. of YOKOSUKA, KURE, SASEBO, and MAIZURU Naval Districts.

Cmdrs. of OMINATO, OSAKA, and CHINKAI Naval Guard Districts.

Cmdrs. in Chief of the Combined Fleet.

Cmdr. in Chief of the Combined Air Fleet.

B. Assignment of the National Defence, Duties Shared by the Army and Navy. By order of Imp. GHQ, the Cmdr. in Chief of the Naval GHQ who was under the direct command of the Emperor assumed the command of the surface, under-water, and air operations by the Naval Air Force in the entire operational areas around the HOMELAND. By order of Imp. GHQ, the Cmdrs. of the 1st and 2nd Gen. Armies and the 15th and 17th Area Armies, who were directly under the Emperor took up the command of various ground forces in their respective operational sectors, leaving entire air units under the Cmdrs. of the Gen. A.A.F. and the 5th Area Army, respectively.

The defense of the KOREA STRAITS was mainly responsible for the Navy, placing the TSUSHIMA FORT under the tactical command of a Naval Cmdr.

C. Principles of Cooperation Between the Army and Navy.

1. It was determined that the land operations would be under the command of the Army and the surface and under-water operations under the Navy as a rule, while carrying out air operations in unison.

2. In land operations, the Cmdrs. of the 1st and 2nd Gen. Armies and the 5th and 17th Area Armies were to assume command of Naval ground forces in their respective operational sectors. However, in the vicinities of Naval ports, the Cmdrs. of the Naval Districts and Guard Districts under the said Army Cmdrs.

were in direct command of the Army and Navy Forces, in their respective sectors so as to smoothly execute the defense of each Naval port which constituted a base for sea operations.

--29--

In order to put Naval ground forces under the tactical command of the Army, the planning of the land defense program and the reorientation and training of personnel were conducted by Army instructors, while new equipment necessary for ground combat was prepared by the Navy.

3. Surface and under-water operations were commanded by the Cmdr. in Chief of the Naval GHQ. Army fortifications which had special missions with sea operation, was to receive orders from Naval Cmdrs. in regard to sea firing, signs for distinguishing our force from the enemy, use of searchlights, etc. which required special pre-arrangement.

4. The highest commanders of Army and Naval Air Forces were to be in one place or in adjacent localities during operation for smooth coordination.

No Air Unit of the Navy was placed under the command of the Army or vita versa.

The Army 7th and 98th Air Regts. trained for sea-operations obtained from the Navy special facilities in regard to the maintenance of torpedoes and the use of necessary bases.

5. The following table shows chains of command for the HOMELAND Operation:

6. Reference (Separate Volumes).

a. Agreement Between the Army and Naval Sections in the Imp. GHQ on the HOMELAND Operation;

Concluded in April 1945.

b. Agreement between the Army and Naval Sections in the Imp. GHQ on the Decisive Air Operation on the HOMELAND; concluded in August 1945.

Attached Sheet No. 1.

Plan for the Disposition and Use of the Army and Navy Air Force.

Gen. AAF

1st A.A.F. Areas east of SUZUKA on Main Is.

Special Attack; 1. Approx. 600 planes

Reserve force for the 6th A.A.F. in the case of the SHIKOKU and KYUSHU Area Operation.

Gen. Attack; 2. Approx. 500 planes

Main force for operations in the KANTO Dist.

6th A.A.F. (Main Is. west of SUZUKA & SHIKOKU, KYUSHU)

General Attack; Approx. 400 planes

Prior to the HOMELAND Operation, fighters among these planes will intercept enemy large bombers over JAPAN PROPER.

Special Attack; Approx. 1000 planes

Main force of A.A.F. and chief strength for operations in the SHIKOKU and KYUSHU Areas.

5th A.A.F. (Main force in KOREA; an element in MANCHURIA & NORTH CHINA

Gen. Attack. 1. Approx. 200 planes

Reserve or relief for the 6th A.A.F. in the case of the SHIKOKU and KYUSHU Operation.

-Special Attack; 2. Approx. 500 planes.

Main strength for operations in SOUTH KOREA

Tote: 1. This disposition will be changed if situation demands.

2. In addition to the above strength, 500 to 1,000 planes will be prepared for special attack by July or August.

--31--

ANNEXED SHEET #3

PRESENT DISPOSITION OF SURFACE AND UNDERWATER SUICIDE UNITS

(Disposition orders issued by 27 July 1945);

UNITS ATTACHED

KORYU (Special Submarine)

KAIRYU (Special Submarine)

KAITEN (Human Torpedo)

SHINYO (Human Torpedo)

Name of Unit

No. of Crafts

Name of Unit

No. of Craft

Name of Unit

No. of Craft

Name of Unit

No. of Craft

OMINATO GUARD DISTRICT 51 Zg.

TOTAL

YOKOSUKA NAVAL DISTRICT

7 SZ

14 Zg

9th

12

146th

25

17 Zg

12th

12

138th

141

50

12 Zg

18th

12

12th

6

55.58

68.129

135.139

225

7 SZ Total

36

6

300

1 SZ

11 Zg

1

2

3

36

14

8

27

56

100

16 Zg

6

12

13

10

51.57

137.140

150

15 Zg

4

5

24

67

136

75

18 Zg

11

12

59

50

YOKOSUKA Zg.

101

102

103

36

1 SZ Total

120

18

375

4 SZ

13 Zg

15

4

60

50

19 Zg

7

8

24

4 SZ Total

24

4

50

HACHIJOSHIMA Zg.

2

8

16

50

YOKOSUKA Naval Dist. (Include HACHIJOSHIMA)

Grand Total

180

36

775

OSAKA Guard Dist.

6 SZ

22 Zg

13

16

24

16

4

66

50

KURE NAVAL DISTRICT

TOTAL

24

4

50

8 SZ

23 Zg

4

6

7

24

49.50

127.128

132

175

21 Zg

17

12

11

8

134

142

50

24 Zg

10

12

B SZ Total

24

32

225

DURA Zg

52

54

56

36

HIKARI Zg

HIRAO Zg

OGAMI Zg

SHODOSHIMA Zg.

58

12

(KASAPO Zg)

(25 Zg)

2 SZ Total

48

--32--

KURE Naval Dist. Grand Total

48

24

32

225

SASEBO NAVAL DISTRICT

5 SZ

35 Zg

8

12

48

116

121

122

124

33 Zg

14

12

3 5

9

10

34

54

126

117

100

32 Zg

15

12

54.47

53.61

53.61

106.112

123.124

125.230

131.133

5 SZ Total

24

46

725

3 SZ

KAWATANA Zg.

42.62

109.110

143.144

200

31 Zg.

10

4

65

34 Zg

118

25

3 SZ Total

4

225

SASEBO Dist. Grand Total

Naval

4

24

46

1000

MAIZURU Naval Dist.

MAIZURU Naval Dist.

11

3

TOTAL

3

CHINKAI WAN Guard Dist.

SAISHUTO

45

119

120

100

TOTAL

100

CHICHIJIMA

Base

CHICHI JIMA

1

2

5

150

HAHAJIMA Guard Dist.

3

4

80

TOTAL

230

OSHIMA Defense Dist.

KIKAI

40

111

75

OSHIMA

1

17

18

44

150

TOTAL

1

225

MIYAKO Kg

MIYAKO

41 50

TOTAL

50

ISHIGAKI

Kg.

ISHIGAKI

19

23

26

58

200

TOTAL

200

TAKAO Guard Dist.

FORMOSA

6

3

20.21

28.29

30.31

102

325

TOTAL

3

325

--33--

MAKO Base

MAKO

24

25

105

125

TOTAL

125

CHUSHAN

kg.

CHUSHAN ISLAND

46.52.104

114.115

(Exclude CHINA Area Fleet of Self Maintenance

175

TOTAL

175

HAINAN Guard Dist.

HAINAN ISLAND

32

33

103

125

TOTAL

125

HONG KONG base

HONGKONG & TAY BAY

35

36

107

125

TOTAL

125

AMOY Base

AMOY

37

108

100

TOTAL

113

100

Combined Fleet

10 SZ

101 Zg

12

102 Zg

6

10 SZ Total

18

TOTAL

18

SZ _____ Submarine Squadron

Zg _____ Submarine Base Unit

Kg _____ Probably Surface Escort Unit

--34--

ANNEXED SHEET #4

ORGANIZATION OF SUICIDE UNITS (15 Aug. 1945)

(on the surface of the water).

GB Combined Fleet

YOKOSUKA Naval District

7 SZ

14 Zg (NONOHAMA)

12 Zg (KATSULLRA)

17 Zg (ONAHAMA)

1 SZ

18 Zg (KATSUYAMA)

11 Zg (ABURATSUBO)

16 Zg (SHIMODA)

15 Zg (ENOURA)

YOKOSUKA Zg

71 Zg. (KURIHAMA)

HACHIJYO-SHIMA Guard Unit

4 SZ

13 Zg (TOBA)

19 Zg (MATOYA)

OSAKA Guard District

6 SZ

22 Zg (KOMATSUSHIMA)

KURE Naval District

2 SZ

HIKARI Zg

HIRAO Zg

OKAMI Zg

KSADO Zg

81 Zg (KURE)

8 SZ

23 Zg (SUSAKI)

21 Zg (SUKUMO)

24 Zg (SAEGI)

35 Zg (HOSOSHIMA)

33 Zg (ABURATSU)

32 Zg (KAGOSHIMA)

5 SZ

SASEBO Naval District

3 SZ

KAWATANA Zg.

31 Zg (YADAKE)

34 Zg (KARATSU)

WM

36 Zg (TSUSHIMA)

MAIZURU

MAIZURU Zg

CHIN-KAI-WAN Guard District

42 Zg (SAISHOTO)

OMINATO Guard District

OMINATO Defense Force

10 SZ

101 Zg (Striking Force)

102 Zg (Striking Force)

OURA Zg

SHODOSHIMA Zg

SZ - Submarine Squadron

Zg - Submarine Base Unit

--35--

AIR STRENGTH

TYPE

5th Air Fleet

3rd Air Fleet

10th Air Attack Forces

12th Air Div.

13th Air Div.

72nd Air Div.

53rd Air Div.

71st Air Div.

Combined Fleet

TOTAL

FOR RECONNAISSANCE

SAIUN (MYRT 11)

40

40

80

Land Attack Bomber (NELL)

50

50

Flying Boat

10

10

100

40

140

For Command of Air

REISEN ZERO Fighter (ZEKE)

50

200

50

200

50

530

SHIDEN (GEORGE 11)

150

120

270

RAIDEN (JACK 11)

30

50

80

Night fighter (IRVING 11)

40

20

60

30

150

120

220

50

410

50

200

1030

FOR ATTACK

Against Attacking Forces Task Force

Carrier Borne Bomber (JUDY 11)

100

100

200

Land Bomber (BETTY)

50

50

Special SAIUN

80

150

100

80

330

Against Occupation Force

Fighter-Bombers

75

125

200

Carrier Borne Bombers (JUDY) (VAL)

50

50

Carrier Borne Attack bomber (KATE)

80

80

40

200

Land Bombers (BETTY)

25

25

Land Attack Bomber (NELL 23)

50

25

25

100

BAKA Bomb

11 Type - 170

22 Type - 60

Seaplanes

70

60

120

250

WHITE CHRYSANTHEMUM (TRAINERS)

20

220 (90)

160

400 (90)

MEDIUM TRAINERS

810

1060

630

TOTAL

275

139

1070

1340

910

GRAND TOTAL

645

490

1100

1340

910

410

50

200

80

5225

--36--

ATTACHED SHEET NO. 2

THE FIRST DISPOSITION PLAN

FOR RECONNAISSANCE

FOR AIR CONTROL (COMMAND OF AIR)

TOTAL ATTACK

TOTAL

AGAINST TASK FORCE

AGAINST INVADING FORCE

COMBAT CRAFT

TRAINERS

Frontal Area Zone for Direct Attack. (24 Air Base)

SAIUN (MYRT 11) 40

Land Attack Bomber (NELL 23) 10

ZERO Fighters (ZEKE 52) 50

SHIDEN (GEORGE 11) 100

Night Fighters (IRVING 11) 40

Carrier Borne Bombers (JUDY or VAL) 50

Bomber Fighters 25

Seaplanes 40

Med. Trainers (VAL 22) 830 (+90)

OKA (CHERRY BLOSSOM) (BAKA Bomb) 30

355

(+ OKA 30)

830

(920)

1,185 (1,275)

(OKA 30)

TOTAL

50

190

50

895 (985) OKA 30

The First Reassembling Zone (30 Air Base)

Flying Boats 4

ZERO Fighters (ZEKE 52) 200

SHIDEN (GEORGE 11) 50

Night Fighters (IRVING 11) 30

Carrier Borne

Bombers 25

(JUDY or VAL)

Bomber-Fighters 75

Carrier Borne Attack Planes (KATE) 80

Seaplanes 130

SHIRAGIKU 130 (WHITE CHRYSANTHEMUM)

Med. Trainers 280 (+390) (OKA 60)

394 5

(+ OKA 60)

(800)

(SHIRAGIKU 90) Trainers)

1.004 (1,394)

(+ SHIRAGIKU 90)

OKA 60

TOTAL

4

280

25

695 (1,085)

SHIRAGIKU 90 (OKA 60)

The Second Reassembling Zone (30 Air Base)

SAIUN (MYRT 11) 20

Land Attack Bombers (NELL 33) 35

Flying Boats 3

ZERO Fighters (ZEKE 52) 100

SHIDEN (GEORGE 11) 100

RAIDEN (JACK 11) 30

Night Fighters (IRVING 11) 30

Carrier Borne

Bombers 75

Bombers BETTY) 50

Bomber-Fighters 100

Carrier Borne Attack

Planes (KATE) 40

Land Attack Bombers (NELL) 25

Seaplanes 20

SHIRAGIKU (Trainers) 220

Med. Trainers 160 (+90)

OKA 40

(+ OKA 40)

380 (470)

1008 (1098)

(+ OKA 40)

TOTAL

58

260

125

565(655)

(OKA 40)

--37--

The Third Reassembling Zone (HQ)

Flying Boats 3

ZERO Fighters (ZEKE 52) 50

Carrier Borne (BOMBERS) (JUDY) 50

233

(+ OKA 20)

80 (110)

313 (343)

(+ OKA 20)

Night Fighters (IRVING 11) 20

Bombers (BETTY) 25

Land Attack Bombers (NELL) 25

Seaplanes 60

SHIRAGIKU 50

Med. Trainers 30 (+ 30) (OKA 20)

TOTAL

3

70

0

240 (270) (+ OKA 20)

The Fourth Reassembling (Zone 14 Air Base)

SAIUN (MYRT 11) 20

Bomber-Fighters

Carrier Borne Bombers 50

Carrier Borne Attack

465 (+ OKA 80)

400

865

Land Attack

130

Planes (KATE) 80

Bombers (NELL 23) 5

SHIDEN

SAIUN (Suicide) 80

Med. Trainers 400

(GEORGE 11) 20

RAIDEN (ZEKE 52) 50

OKA 80

Night Fighters (IRVING 11) 30

TOTAL

25

230

130

The Rear Zone (3 Air Base)

Land Attack Bombers (NELL 23) 50

50

200

250

Med. Trainers 200

TOTAL

0

0

0

250

GRAND TOTAL

140

1,030

330

3,1[]5 (3,725)

2,325

2,300 (2,900)

4,625

(5,225)

COMBAT CRAFTS 825

TRAINERS 2,300 (+ 600)

--38--

Main Points of the Agreement between the Army and the Navy Concerning the Homeland Operation

8 April 1945

Navy Dept., Imp, G.H.Q.

Army Dept., Imp. G.H.Q.

I. Main Points of the Agreement between the Army and the Navy Concerning the Homeland Operations.

A. This agreement deals mainly with the preparations by the Army and the Navy in JAPAN Proper, KOREA, SAKHALIN and surrounding seas excluding the SOUTHWESTERN ISLANDS and with the operations designed to check the invasion of these areas by our principal enemy the AMERICAN Army.

B. As a general rule, the Army will take charge of the land operation and the Navy will be responsible for the sea and submarine operations. The air operations will be dealt with separately.

C. As far as land operations are concerned the 1st General Army Cmdr., the 2nd General Army Cmdr., together with the 5th and 17th Area Army Cmdrs., (from now on called "the Supreme Cmdr." of their respective zone), assuming the command over the local Marine combat units, will be responsible for the entire land operations in their respective areas. In those operation areas, which are near the Naval ports or important harbors (the operation boundaries are shown in Appended Maps No. 1 to 7, however if the enemy major landing operations are anticipated those provisional boundaries may be extended or contracted at discretion of the Army Supr. Cmdr. of

the area concerned) the land operations will be carried out under the direction of the Naval station or the Naval Gd. Dist. Cmdr. (from now on called Naval Supreme Cmdr.) who will also assume the command over the local Army and Naval units if directed so by the Army Supr. Cmdr. of that area.

The operation preparation, the measures necessary for influentation of defense plan in the area as well as the training

--39--

of personnel will be under direction of Army Supr. Cmdr. of the area.

D. The sea and submarine operations will be directed by the Cmdr.-in-Chief of the Combined Fleet. The TSUSHIMA Fortress will be placed under the command of the Navy Supr. Cmdr. of the KOREAN STRAITS Area. The Army units (mentioned in Appended Chart No. 1) stationed in that area as well as the Naval Shore Batteries under Its command will take orders from the local Naval Supr. Cmdr. in all actions demanding the shelling of the sea areas, the handling of the searchlights and in matters of distinguishing between friend and foe.

E. The disposition of troops including the A.A. Def. Units and the A.A. DeF. Intell. Units, will be determined, by the mutual agreements between the Army and Navy. If the enemy landing is anticipated, the Navy (or Army) A.A. Def. Unit in the local operation zone will take orders from the Army (or Navy) Supr. Cmdr., whoever is the Sr. Cmdr. of the area in question.

F. The Army and Navy's major defense and suicide squadrons' bases as well as other important installations will be protected Jointly by Army and Navy units (land security guards). If the enemy landing Is foreseen, land operations will be carried by the Army and Navy joint efforts.

G. The Naval units mentioned in E and F, during the period of operation preparations, will be under the command of the Sr. Array Cmdr. who will be in charge of defense measures and the training of personnel.

H. The disposition of the sea and submarine suicide bases must be planned in such a way that by coordinating their location with the land defense installations the maximum strength can be concentrated at the points likely to chosen by the enemy for his landing operations. In case of emergency the local Army Supr. Cmdr. will assist the Navy in establishing Naval suicide bases. (The general disposition of the Naval suicide bases is shown in Appended Chart No. 2).

--40--

I. The chain of command established by this agreement is as follows:

1st General Army Cmdr.

11th Area Army Cmdr.

13th Area Army Cmdr.

13th Area Army Cmdr.

Cmdr.-in-Chief of the Combined Fleet

Cmdr. of Naval Station.

Cmdr. of Naval Gd. Dist.

2nd General Army Cmdr.

15th Area Army Cmdr.

16th Area Army Cmdr.

Cmdr.-in-Chief of the Combined Fleet

Cmdr, of Naval Station.

Cmdr, of Naval Gd. Dist.

5th Area Army Cmdr.

Cmdr.-in-Chief-of-Combined Fleet OMINATO Naval Gd, Dist. Cmdr.

17th Area Army Cmdr.

Cmdr.-in-Chief-of-Combined Fleet CHINKAI Naval Gd. Dist. Cmdr.

The "Arrangement between the Army and the Navy Concerning the Division of Duties in the Defense of the Homeland," enacted in Aug. 1943 is abolished and supplemented with the present one. However the following clauses of the old agreement will still be in force: Clauses 3, 8, 9, 12, 14, 17, 18, 19 (concerning the responsibility of the Army Cmdr. for the transmission of alarm signals by means of the wireless) 23 to 26, 88 and 30,

--41--

Appended Chart No. 1

The Amy Units which will be under Orders of the Navy during the Sea Operations

Unit

Commander

SOYA Fortress Unit

OMINATO Naval Gd. Dist.

TSUGARU Fortress Unit

TOKYO BAY Fortress Unit

YOKOSUKA Naval Base

Unit protecting entrance of ISE BAY

YURA Fortress Unit

OSAKA Naval Gd. Dist.

BUNGO Fortress Unit

KURE Naval Base

MAIZURU Fortress Unit

MAIZURU Naval Base

Part of SHIMONOSEKI Fortress Unit

SASEBO Naval Base

Part of IKI Fortress Unit

Part of FUZAN Fortress Unit

Unit protecting the entrance of KAGOSHIMA BAY

NOTE: 1. The Army batteries that are established for the defense and land operation purposes, will in case of necessity, cooperate in the sea operations. The details of such cooperation will be worked out jointly by Army and Navy local commanders.

2. Parts of the units attached to the SHIMONOSEKI, IKI and FUZAN Fortresses are assigned mainly for the purpose to assist in the sea operations designed to blockade the KOREAN STRAITS.

3. The details of their participation in actions will be worked out by the local Army and Navy Cmdrs.

Appended Chart No. 8

Approximate Locations of Navy Suicide Bases

AREA

DISTRICT

CLASSIFICATION

KORYU, KAIRYU Sp. Submarine

KAITEN Human Torpedo

SHINYO Suicide Boats

KYUSHU

KAGOSHIMA

0

CHIRIN

0

YAMAKAWA

0

0

IBUSUKI

0

ABURATSU

0

0

0

ARIAKE BAY

0

0

HOSOJIMA

0

0

0

MIMITSU

0

KATAURA

0

UFUKA (AMAKUSA)

0

0

AIURA

0

GOTO

0

0

KARATSU

0

0

0

SOUTH KOREA

CHINKAI

0

0

REISUI Vicinity

0

TSUSHIMA

0

SAISHU ISLAND

0

0

0

SHIKOKU

SUZAKI

0

0

0

KAMINOKAE Vicinity

0

0

KOCHI Vicinity

0

SUKUMO

0

KOMATSU ISLAND

0

--42--

APPENDED MAP NO. 1

CHUBU District

YARATABE Vicinity

0

TOBA

0

0

0

HAMANA LAKE

0

0

NUMAZU and MATSUZAKI

0

0

IZU PENINSULA

0

KANTO District

ABURA TSUBO

0

KAOJIRO Vicinity

0

0

KATSUURA

0

0

0

CHOSHI Vicinity

0

ONAHAMA

0

0

0

HACHIJO INLINE

0

0

TOHOKU District

ISHINOMAKI Vicinity

0

0

0

OMINATO

0

HACHINOHE Vicinity

0

0

0

1. If necessity demands the local commanders may change the base location.

2. The establishment of a chain of bases for facilitating the concentration of KORYU and KAIRYU Submarines is still under consideration.

Appended Chart No. 2

Land Operation Area under the Command of KURE Naval Base

HIROSHIMA PREFECTURE, KURE CITY

AKI COUNTY Area

OYA VILLAGE, SHOWA VILLAGE, KUMANO TOWN, EDA JIMA VILLAGE, ONDO TOWN, KURAHASHI JIMA VILLAGE, SHIMOKAMOKARI JIMA VILLAGE, KAMIKAMOKARI VILLAGE

HIROSHIMA CITY Area

BENTEN JIMA, within NIHO TOWN, SHO BENTEN JIMA.

KAMO COUNTY Area

GOHARA VILLAGE, SHIMO KUROSE VILLAGE, NAKA KUROSE VILLAGE, KAMI KUROSE VILLAGE, NOMIO VILLAGE, KAWAJIRI TOWN, NORO VILLAGE, MITSUKUCHI TOWN, UCHIMI TOWN, ANDO VILLAGE.

TOYODA COUNTY Area

TOYOHAMA VILLAGE, OKUHI JIMA, ITSUKI JIMA, SUZUME ISO.

SAIGI COUNTY Area

MITAKA VILLAGE, TAKATA VILLAGE, NAKA VILLAGE, OKI VILLAGE, HITONOSE VILLAGE, KANOKAWA VILLAGE, FUKAE VILLAGE, OGAKI TOWN, OTAKE TOWN, KONO VILLAGE, OGATA VILLAGE.

YAMAGUCHI PREFECTURE IWAKUNI CITY

KOGA COUNTY Area -

WAKI VILLAGE, KABUTO JIMA within YUMACHI (part of KABUTO in YUMACHI).

OSHIMA COUNTY Area

YUDA VILLAGE, WADA VILLAGE, MORINO VILLAGE, SHIROKI VILLAGE, HIRAI VILLAGE, AGENOSHO TOWN, OKIURA VILLAGE, KUGA TOWN, KAMANO VILLAGE, YASHIRO VILLAGE, KOMATSU VILLAGE.

--43--

ONSEN COUNTY Area -

MUTSUNO VILLAGE, NISHI NAKAJIMA VILLAGE, HIGASHI NAKAJIMA VILLAGE, SHINWA VILLAGE, YASUI JIMA and KOYASUIJIMA, HOJO TOWN, SHIRAISHI.

APPENDED MAP NO. 2

--45--

APPENDED MAP NO. 3

APPENDED MAP NO. 4

APPENDED MAP NO. 5

APPENDED MAP NO. 6

APPENDED MAP NO. 7

Main Points of the Agreement between the Army and the Navy Concerning, the Air Operation "KETSU"

13 July 1945

Navy Dept., Imp. G.H.Q.

Army Dept., Imp. G.H.Q.

NOTE: This agreement deals principally with the defensive operations directed against the enemy attacks in WESTERN JAPAN.

I. Main Points of the Agreement between the Army and Navy Concerning Air Operation "KETSU."

A. Aim.

1. The entire Army and Navy Air Forces must jointly strive to destroy the enemy at sea in the earliest possible stage of invasion or failing that must coordinate its actions with the land operations designed to annihilate the enemy landing force on the beaches.

2. Strengthening the Air Defense of the Homeland and Aiding the Anti-Submarine Operations.

B. Outline of the Operations.

1. The main object of the air operation in protecting the Homeland against enemy invasion is to destroy the enemy landing convoys by means of suicide attacks. With this purpose in view the following arrangements were made:

a. The first priority in battle preparations was given to KYUSHU, SHIKOKU and SOUTHERN KOREA Areas where special positions are prepared and strengthened. Arrangements are being made to gradually complete the preparations in other areas, especially in the KANTO Area.

b. In order to discover the enemy's main plan of attack all efforts must be made to reconnoiter his advance bases and his lines of operations.

c. Concentrating the maximum strength (within about 10 days) the efforts must be made to attack persistently day and night the enemy landing convoys before they can reach their

--51--

anchorage, endeavoring by repeated and valiant assault, to annihilate them at their anchorage if they manage to reach it.

d. Boldly attack the enemy task forces in order to prevent them from giving an effective cover to their landing convoys.

e. In order to suppress the enemy Naval gun fire the following rules must be adopted by our entire force cooperating in land operations.

1). A part of the fighting strength will be utilized to gradually diminish the domination of the enemy naval fire power prior to his landing on the beaches.

2). To facilitate the land operations the air force must attack the enemy Naval squadrons timing its actions with the land forces' moves.

f. In order to facilitate the task of crushing the enemy force at the time of his landing on the Homeland beaches we must attack him checking his operations in our outlying islands (GOTO ISLAND, TANEGA SHIMA and seven islands of the IZU GROUP) and supply necessary strength to prevent his invading of SAISHUTO ISLAND.

2.

a. Enforcing the aerial defense and anti-submarine operation before the "KETSU" Operation actually starts, the Army using all its combined air force must endeavor by skillful counterattack to repulse the enemy air-raids on the Homeland. The Navy will cooperate with the Army in all these operations.

b. The Army and Navy will cooperate in a surprise attack designed to neutralize the main enemy heavy bombers' bases, especially those in the MARIANAS, IWO JIMA and OKINAWA Areas.

c. The Navy strengthening the anti-submarine operation in the JAPAN SEA Area, will endeavor to check the enemy submarine penetration by sweeping them off the seas. The Army will cooperate with the Navy in all these operations.

d. The Army and Navy will cooperate in the operation aimed at neutralizing the enemy mine blockade of our main harbors.

--52--

3. In case the enemy prior to his invasion of JAPAN Proper should begin the operation in OGASAWARA (BONIN) ISLANDS and in CENTRAL CHINA Area we must endeavor with a part of our forces to inflict on him as many casualties as possible in order to delay the achievement of his aims.

c. Outline of the Plan Concerning the Disposition and Utilization of Military Strength.

1. Plan for the Disposition and Utilization of the Army Air Force is shown in Appended Sheet No. 1.

2. Plan for the Disposition and Utilization of the Navy Air Force is shown in Appended Sheet No. 2.

D. The Command.

The principal rule in all operations will be the cooperation between Army and Navy forces. The Cmdr.-in-Chief of the Air Force will, immediately upon the agreement between the local Army and Navy Cmdrs.-in-Chief, establish his post either at his present position or transfer it to another place from which he will easily coordinate the operations of the Army and the Navy Air Forces.

E. Miscellany.

1. With the matters concerning the communication, use of the air bases, supplies and preparation of ammunition and fuel, being regulated by "The Main Agreement between the Army and Navy Concerning Air Operation" of 1 Mar. 1945 and "The Main Agreement between the Army and the Navy Concerning the Use of Air Bases in the Homeland" of 8 Apr. 1945, both the Army and the Navy will employ their respective air forces to the best advantage of mutual cooperation.

2. Every possible step must be taken to conserve the fighting power by strengthening, dispersing, and camouflaging the air bases.

3. If necessity arises to define some details of the main agreement the final decision will be made by agreement between the following commanders:

--53--

Cmdr. of the General Air Army

Cmdr. of the 1st Army Air Force.

Cmdr. of the 5th Army Air Force.

Cmdr. of the 6th Army Air Force.

Cmdr.-in-Chief of the Navy

Cmdr.-in-Chief of the 3rd Navy Air Force.

Cmdr.-in-Chief of the 5th Navy Air Force.

Cmdr.-in-Chief of the 10th Navy Air Force.

4. All Important matters not mentioned in this agreement will be decided upon, according to the circumstances.

--54--

APPENDED SHEET NO. 1

PLAN FOR THE DISPOSITION AND UTILIZATION OF THE ARMY AIR FORCE

The General Air Army

1st Air Amy (HONSHU, east of SUZUKA)

Approx. 600 suicide planes

1. The 1st Air Army will serve as the reserve of the 6th Air Force in the event of an operation in KYUSHU and SHIKOKU Area.

Approx. 500 regular planes

2. The 1st Air Army will be the main strength in the event of an operation in the KANTO Area. Concentrating as much as possible the fighter air plane strength before Operation "KETSU", a a strong counterattack on the enemy heavy bombers attacking the Homeland must be executed. The main force of the General Air Army will serve as a backbone, in the operation in SHIKOKU and KYUSHU Areas.

6th Air Army (HONSHU, west of SUZUKA, SHIKOKU and KYUSHU).

Approx. 400 regular planes

Approx. 1000 regular planes

5th Air Force (Main force in KOREA, parts in MANCHURIA and NORTH CHINA).

Approx. 200 regular planes

1. The 5th Air Force will assist or serve as the reserve for the 6th Air Force in event of our operation in KYUSHU and SHIKOKU Area.

Approx. 500 suicide planes

2. Backbone in event of an operation in the SOUTHERN KOREA Area.

NOTE 1. The disposition of air power mentioned in this sheet may change according to circumstances.

2. In July and August from 500 to 1,000 airplanes (besides these mentioned in this sheet) will be completely equipped for service in suicide attacks.

--55--

Appended Sheet NO. 2 (Part 1)

Plan for the Disposition and Utilization of the Navy Air Force.

RECONNAISSANCE

AIR CONTROL

AGAINST (KDB) ATTACKING FORCE

AGAINST ATTACK TROOPS

TOTAL PLANES

GRAND TOTAL

SERVICE

TRAINING

First Line Position Area

(24 Air Bases)

SAIUN (MYRT 11)

Land attack Bombers

40

10

REISEN (ZEKE 52)

50

Carrier Borne Bombers

(TvDy or Val)

50

Fighter Bombers

25

355

830

1185

SHIDEN (GEORGE 11)

100

Seaplanes

40

(+ OKA 30))

(1275)

Night fighter (TRIVING 11)

40

Med Trainers

830

(+ OKA 30)

(VAL 22) planes (+ 90)

OKA CHERRY 30

BLOSSOM (BAKA bomb)

Total

50

190

50

895 (985)

(+ OKA 30)

Second Line Area

(30 Air Bases)

Flying Boats

4

REISEN

200

Carrier Borne Bombers

25

Fighter Bombers

75

594

410

SHIDEN

50

Carrier Borne Attack Planes

80

(+ OKA 60)

(800)

(1394)

Night Fighter

30

Seaplanes

130

(+ SHIRA GIKU 90)

(+ SHIRA GIKU 90)

SHIRAGIKU (White Chrysanthemum) (+ 90)

130

(OKA 60)

Mod Trainers

200

(Val 22)

(+ 390)

(OKA 60)

Total

4

280

25

695 (1085)

(+ SHIRAGIKU 90)

(OKA 60)

Third Line Area

(20 Air Bases)

SAIUN

Land Attack Bombers

Flying Boats

20

35

3

REISEN

100

Carrier Borne Bombers

75

Fighter Bombers

100

+ 628

380

1008

SHIDEN

100

Land Bombers

50

Carrier Borne Attack Planes

40

(+ OKA 40)

(470)

(1090)

RAIDEN (JACK 11)

30

Land Attack Bomber

25

(+ OKA 40)

Night Fighters

30

Seaplanes

20

SHIRAGIKU

220

Mad Trainers

160

(+ OKA 40)

(+ 90)

Total

260

125

(+ OKA 40)

565 (655)

Fourth Line Area

(12 Air Bases)

Flying Boat

3

REISEN

Night Fighters

50

20

Carrier Borne Bombers

50

233 (+ OKA 20)

80 (110)

313 (843)

Lead Bombers

25

(OKA 20)

Land Attack Bomber

25

Seaplanes

60

SHIRAGIKU

50

Med Trainers (+ 30)

30

(OKA 20)

Total

3

70

0

240 (270)

(OKA 20)

--56--

APPENDED SHEET NO. 2 (Part 1) (Cont'd)

Fifth Line Area

(14 Air Bases)

SAIUN

20

Fighter Bombers

130

Carriers Borne Bombers

50

Carrier Borne Attack Planes

80

465 (+ OKA 80)

400

865 (+ OKA 80)

Land Attack Bombers

5

SHIDEN

20

SAIUN (Suicide)

80

Med Trainers (+ OKA 80)

400

RAIDEN

50

Night Fighters

30

Total

25

230

130

480

(+ OKA 80)

Rear Area

(3 Air Bases)

Land Attack Bombers

50

50

200

250

Med Trainers

200

Total

0

0

0

250

Grand Total

140

1030

330

Service Planes

3125

(3725)

2325

2300 (2900)

4685

(5225)

Trng Planes

2300

(+ 600)

--57--

DATA CONCERNING THE DEFENSE INSTALLATIONS (20-12)

TABLE SHOWING THE DISPOSITION OF LOW TRAJECTORY BATTERIES

LOCATION

CLASSIFICATION OF GUN

NO. OF GUN

NO. OF BATTERIES

REMARKS

SAKHALIN

NISHINOTORO

15 Cm. Gun

4

HOKKAIDO

SOYA

15 Cm. Gun

4

Ammunition not yet delivered

12 Cm. Gun

2

AKKESHI

12 Cm. Gun

4

SHIOKUBI

14 Cm. Gun

3

TSUGARU PENINSULA

12 Cm. Gun

4

SHIMOKITA PENINSULA

14 Cm. Gun

4

12.7 Cm. Gun

6

12 Cm. Gun

14

12 Cm. A. A. Gun

2

8 Cm. Gun

4

8 Cm. A. A. Gun

8

20 Cm. Howitzer Gun

12

12 Cm. Howitzer Gun

20

8 Cm. Howitzer Gun

4

Infantry Gun

2

SOUTHEAST COAST OF BOSO PENINSULA

12 Cm. A. A. Gun

8

Two 12 Cm. A. A. Guns and two 8 Cm. Guns are in Army disposition

8 Cm. Gun

4

8 Cm. Howitzer Gun

2

SOUTHWEST COAST OF BOSO PENINSULA

14 Cm. Gun

2

12.7 Cm. Gun

4

12 Cm. A. A. Gun

10

8 Cm. Gun

2

In Army disposition

EASTERN COAST OF MIURA PENINSULA

14 Cm. Gun

4

20 Cm. Gun

2

15.5 Cm. Gun

2

12.7 Cm. Gun

3

12 Cm. A. A. Gun

6

15 Cm. Gun

10

100 rounds per gun

WESTERN COAST OF MIURA PENINSULA

14 Cm. Gun

2

12 Cm. A. A. Gun

2

12 Ga. Howitzer Gun

1

8 Cm. Gun

8

8 Cm. Howitzer Gun

2

SHICHIRIGAHAMA

14 Cm. Gun

3

12 Cm. Howitzer Gun

1

8 Cm. Gun

1

--58--

HONSHU

EOSHIMA ISLAND

14 Cm. Gun

2

12.7 Cm. Gun

5

15 Cm. Gun

1

SAGAMI BAY

14 Cm. Gun

8

In Army disposition

EASTERN COAST OF IZU

15.5 Cm. Gun

1

8 Cm. Gun

4

8 Cm. Howitzer Can

2

SURUGA BAY

14 Cm. Gun

4

12 Cm. A.A. Gun

4

ISE BAY

14 Cm. Gun

6

KII CHANNEL

15 Cm. Gun

8

Ammunition not yet delivered

14 Cm. Gun

1

SHIKOKU

BUNGO CHANNEL

15 Cm. Gun

10

600 rounds

14 Cm. Qua

4

Ammunition not yet delivered

SUKUMO Area

15 Cm. Gun

2

12 Cm. A.A. Gun

4

8 Cm. A.A. Gun

4

8 Caw Howitzer Gun

1

KYUSHU

Outside of SANEBO HARBOR

15 Cm. Gun

2

100 rounds per gun

12.7 Cm. Gun

4

GOTO ISLAND

12 Cm. Gun

3

400 rounds

8 Cm. Gun

6

100 rounds

8 Cm. Howitzer Gun

2

IKEZUKI BAY

14 Cm. Gun

2

IKI

14 Cm. Gun

4

FUKUOKA Area

14 Cm. Gun

2

8 Cm. Howitzer Gun

6

TACHIBANA BAY

12 Cm. Gun

2

100 rounds per gun

12 Cm. Howitzer Gun

8

MIYAZAKI Area

15 Cm. Gun

6

14 Cm. Gun

2

HAYASAKI STRAITS

15 Cm. Gun

4

100 rounds

12 Cm. Gun

4

200 "

NAGASHIMA STRAITS

14 Cm. Gun

2

200 "

12 Cm. Gun

2

100 "

SATSUMA PENINSULA

15 Ga. Gun

2

100 rds. each four 12 Cm. guns are in disposition of the Army.

12 Cm. Gun

6

Entrance to KAGOSHIMA BAY

15 Cm. Gun

2

100 rounds

14 Cm. Gun

4

200 rounds

12 Cm. Gun

2

200 "

TOTAL 326

--59--