J.C.S. 1388/4
11 July 1945
JOINT CHIEFS OF STAFF
DETAILS OF THE CAMPAIGN AGAINST JAPAN
Reference: J.C.S. 1388 Series
Report by the Joint Staff Planners
1. The Enclosure is a revision of J.C.S. 1388 which includes:
2. The Joint Staff Planners recommend that the Enclosure be presented to the President.
DISTRIBUTION COPY NO. COPY NO. Admiral Leahy 1 General Norstad 11 General Marshall 2 & 5 Admiral Gardner 12 Admiral King 3 & 6 General Cabell 13 General Arnold 4 General Lincoln 14 General Handy 7 Captain Campbell 15 Admiral Edwards 8 Secy, JCS 16 Admiral Cooke 9 Secy, JPS 17 General Hull 10 Secy, JWPC 18
E N C L O S U R E
MEMORANDUM FOR THE PRESIDENT:
Subject: Campaign against Japan.
1. Strategy. Throughout the series of staff conferences with the British, we have agreed that the over-all concept for the prosecution of the war included provision "to bring about at the earliest possible date the unconditional surrender of Japan." We believe that the only sure way, and certainly the quickest way to force the surrender of Japan is to defeat her armed forces in the main Japanese islands. Hence, at recent staff conferences we have proposed--and the British have agreed--that the over-all objective of the Japanese war is "to force the unconditional surrender of Japan by (1) lowering Japanese ability and will to resist by establishing sea and air blockades, conducting intensive air bombardment and destroying Japanese air and naval strength; (2) invading and seizing objectives in the industrial heart of Japan."
It is by no means certain that a capitulation by a Japanese government will be recognized by Japanese armed forces everywhere. If, following such an acknowledgment, her forces do not surrender, their position will be so seriously weakened as to facilitate their defeat in detail. However, the possibility must be faced that the Japanese forces everywhere must be defeated.
2. Presently planned campaign. Our agreed concept of opera-
tions for the main effort in the Pacific war is:
"Following the Okinawa operation to seize additional positions to intensify the blockade and air bombardment of Japan in order to create a situation favorable
"An assault on Kyushu for the purpose of further reducing Japanese capabilities by containing and destroying major-enemy forces and further intensifying the blockade and air-bombardment in order to establish a tactical condition favorable to:
"The decisive invasion of the industrial heart of Japan through the Tokyo Plain."
Our campaign plans have therefore been designed to seize positions progressively closer to the Tokyo Plain--the political, industrial and communication center of Japan--with a view to isolating the Japanese islands and providing sufficient bases from which, by sea and air bombardment, conditions will be created which will make ultimate invasion of the Tokyo Plain acceptable and feasible. We have also endeavored so to design the campaign that the Japanese cannot fail to see and feel the results of its rapidly increasing tempo and magnitude, with the thought that at some stage of the campaign they will admit defeat in order to avoid further destruction.
Thus far in this campaign we have seized and developed air and naval bases in the Marianas, Iwo Jima, the Philippines and Okinawa. No further operations in the Ryukyus after completion of the Okinawa campaign are now contemplated; all available resources are being utilized to develop air and naval bases in Okinawa to maximum capacity by November 1945. By then it is expected to have about 2700 land-based aircraft operating from this area and to have completed an advanced fleet base and anchorage. The map, Tab "A", shows the land-based aircraft expected to be based within range of japan by that time and the areas they can reach. Meanwhile every effort is also being made to transport to the Pacific from Europe the added means required for a rapid and decisive campaign. In general the units needed to build the required bases are being moved first, followed by the required additional combat units, air and ground.
Already we have eliminated practically all Japanese sea traffic between their main islands and points to the southward of Shanghai, and severely restricted their traffic to Shanghai and Yellow Sea ports. By November 1945, when air operations from Okinawa will be in full swing, there should remain to the Japanese only those sea routes across Tsushima Strait to Korea and across the Sea of Japan. It should be noted that our air and submarines are already operating in these areas on a limited scale. By November 1945 the Japanese situation is expected to be critical; their fleet units in home waters have already been so reduced as to no longer constitute a strategic factor; their air arm is already committing training planes to combat and will probably continue to concentrate on maximum suicide tactics; their ability to move ground forces to Japan from Asia or vice versa is already strictly reduced. The map, Tab “D”, shows the estimated Japanese dispositions of ground and air forces about 1 November 1945.
In order to obtain bases still closer to the Tokyo Plain from which to augment sea and air bombardment, complete the isolation of the main Japanese islands and to provide direct air cover and support for the invasion of the Tokyo Plain, should that prove necessary, we have directed General MacArthur and Admiral Nimitz to invade southern Kyushu about 1 November 1945.
We have not yet directed the execution of any operations after the invasion of southern Kyushu, feeling that decision would better await further developments. However, plans and preparations are being made to invade the Tokyo Plain--the political, industrial and communication center of Japan—about 4 months after the southern Kyushu operation, or about 1 March 1946. We consider that this operation should be decisive. By planning and preparing for a supreme operation of this magnitude, we shall be in a position to undertake any lesser operation should developments warrant.
In the period prior to the planned invasion of the Tokyo Plain, every effort will be made to exploit the blockade and bombardment of Japan. In this period, from bases presently and prospectively available, more bombs will be dropped on Japan than were delivered against Germany during the entire European war. If the blockade and bombardment concept is capable of achieving decisive results, these will, in all probability, be brought about by this scale of effort prior to the planned date for the invasion of the Tokyo Plain. However, in the event this invasion is not considered feasible and acceptable on the planned date, a course of action to extend bombardment and blockade is open to us.
3. Examination of the map, Tab "A", shows that bases on the Asiatic mainland other than in Korea are too distant to be of value in augmenting our present capabilities for sea and air bombardment of Japan and in cutting the remaining Japanese sea. routes across Tsushima. Strait and the Sea of Japan. Furthermore, the blockade of the Yellow Sea and the sea areas to the southward is now virtually effective. There is also the likelihood that any operation in North China, with its vast area and large numbers of Japanese ground forces, will develop into a vacuum drawing ever more and more U.S. forces into an indecisive and costly campaign. We therefore discarded, as unnecessary and diversionary, operations to seize bases on the coast of North China. The best areas from which to complete the isolation of Japan are obviously either in Korea or in the southwestern part of the Japanese Archipelago. We considered three possibilities: Korea, the northwestern part of Kyushu, and southern Kyushu. Tab "F" shows the salient facts and estimates for campaigns in Korea.
We discarded Korea as a possible operation to follow Okinawa because of its longer sea approach, the paucity of good beaches and exits therefrom, the rugged terrain back of the beaches, the few airfield sites available for development after seizure, and the great reinforcement capabilities of the Japanese from their fine and as yet untouched army in northern China. Furthermore, because of the distance from Okinawa bases, we would have great difficulty in interfering by air action with the arrival of Japanese reinforcements and in providing adequate air cover and support to the assault. The campaign is estimated to require about the same commitment of forces as for the invasion of southern Kyushu (14 divisions).
Similarly we considered northwestern Kyushu unsuitable as an initial objective area following Okinawa because the sea approaches to the best landing area are restricted, well fortified and heavily mined; and because of Japanese capability to reinforce the area from two directions--from southern Kyushu and from Honshu. The forces required, for such an operation are estimated to be in excess of those for southern Kyushu.
The seizure of southern Kyushu has been directed because;
4. As to other areas, Admiral Mountbatten in the Southeast Asia Command plans to seize a position in the Port Swettenham-Port Dixon area on the Malay Peninsula in the latter half of August 1945 and to follow this up with a campaign to recapture Singapore beginning probably in December-January. General Wedemeyer has advised that, in China, the Generalissimo plans to launch an overland advance with Chinese forces on the Canton-Hong Kong area beginning about 1 September 1945 and to follow up any Japanese withdrawals northward along the railroad route in central China.
Plans for the period after the invasion of the Tokyo Plain cannot be made with firmness at this time. If the Japanese continue to resist, plans must provide for further operations in the main islands and for operations by ourselves or our allies on the mainland of Asia against those Japanese forces which continue to resist. We are striving to keep U.S. commitments on the mainland to a minimum, through encouraging and supporting maximum effort by the Chinese, and by the Russians if they should enter the war. Hence, plans provide for continued U.S. aid to Chinese forces, the scale of which can probably be materially increased later in the campaign. Should the Japanese unconditionally surrender or concede defeat during the campaign in Japan proper, there will still remain the sizable task of disarming their forces everywhere, assembling them at ports, and returning them to their home islands.
6. Forces required for presently planned campaign. Estimates of the forces required to execute the invasion of southern Kyushu and of the Tokyo Plain are shown on the map, Tab "E". The maps, Tabs "B" and "C", show the deployment of land-based aircraft planned upon the completion of each of these two operations. It is obvious from the maps that this air power will cover Japan and the approaches thereto with a blanket of destruction.
For the campaign as planned through the invasion of the Tokyo Plain, it is expected there will be in the Pacific theaters, India Burma and China, by the spring of 1946 a total of 39 Army divisions and 127 Army air groups (8,500 land-based aircraft) or a grand total in Army forces of about 5,000,000 men. General MacArthur has indicated that if operations are necessary after the invasion of the Tokyo Plain, plans should provide for the movement of additional divisions from the U.S. to the Pacific at a rate of about 4 additional divisions per month, from a planned strategic reserve of 17 divisions in the U.S.
By 1 March 1946 the following major naval vessels are scheduled for deployment in the Pacific:
10 BB (Battleships) 26 CA (Heavy Cruisers)
13 OBB (Old Battleships) 33 CL (Light Cruisers)
2 CB (Large Cruisers) 3 CL (AA) (Light Cruisers)
22 CV (Aircraft Carriers) (Antiaircraft)
364 DD (Destroyers)
2 CVB (Aircraft Carriers (Large))
326 DE (Destroyer Escort
9 CVL (Aircraft Carriers (Small)) Vessels)
74 CVE (43 combat) 189 SS (Submarines)
(Aircraft Carriers, Escort)
799 LST (Tank Landing Ships)
17 AGC (Operations and Command
Headquarters Ships) 491 LSM (Medium Landing Ships)
223 APA (Attack Transport Ships)
108 AKA (Attack Cargo Ships)
The above figures make no allowance for attrition. Three months after the Kyushu operation it is estimated that approximately 10% will either have been lost or still undergoing repairs to damage received in this operation. Of the operational ships in service 75% will normally be available for any single operation. Others will be either undergoing operational repairs or be otherwise employed. It is worthy of note that the amphibious resources listed above will permit simultaneous assault landings on a scale never before thought possible.
It is estimated that approximately 3,600 carrier-based aircraft will be available on 1 March 1946.
As a general statement it may be said that the forces of all arms which are required and which should be employed for the operations we contemplate are all those which can be supported in the theater within the means which will be available to us and which can be effectively employed. We feel that the unremitting application of this maximum force is essential to defeating Japan at the least possible cost in lives and resources.
7. Casualties. Our casualty experience in the Pacific war has been so diverse as to throw serious doubt on the validity of any quantitative estimate of casualties for future operations. The following data indicate results of experience.
Jap Casualties Ratio
U.S. Casualties Killed and Prisoners U.S.
Campaign Killed, wounded, missing (Not including wounded) to Jap Leyte 17,000 78,000
Luzon 31,000 156,000 1:5.0
Iwo Jima 20,000 25,000 1:1.25
Okinawa 39,000 (Ground) 119,000
7,700 (Navy) (not a complete count) Normandy
(1st 30 days) 42,000 - _ _
The record of General MacArthur's operations from 1 March 1944 through 1 May 1945 shows 13,742 U.S. killed compared to 310,165 Japanese killed, or a ratio of 22 to 1. During this same period the total U.S. casualties, killed, wounded and missing, were 63,510 or a ratio of approximately 5 to 1.
The nature of the objective area in Kyushu gives maneuver room for land and sea operations. For these and other reasons it is probable that the cost in ground force casualties for the first 30 days of the Kyushu operation will be on the order of that for Luzon. Naval casualties will probably be at about the same rate as for Okinawa.
A paraphrase of General MacArthur's comments on the Kyushu operation follows:
BEGINS. The operation presents less hazards of excessive loss than any other that has been suggested. Its decisive effect will eventually save lives by eliminating wasteful operations of non-decisive character. The operation is the most economical in effort and lives that is possible. It must be remembered that the several months preceding the operation will involve practically no losses in ground troops and that sooner or later a decisive ground attack must be made. Additional subsidiary attacks will simply build up our final total casualties. I most earnestly recommend no change in the operation for the invasion of southern Kyushu. ENDS.
As regards invasion of the Tokyo Plain the number and extent of beaches suitable for amphibious assault preclude concentration of defense. Furthermore, the terrain of the Tokyo Plain permits us to exploit our superiority in maneuver and in equipment.
8. Time. Under the campaign as planned, it is estimated that the defeat of the Japanese in the Tokyo Plain area and the seizure of ports on Tokyo Bay would be completed by mid-1946. Should it prove necessary to execute other operations prior to invading the Tokyo Plain, the earliest date by which the latter operation could take place is estimated to be October 1946, because of adverse weather and ground conditions and the necessity of further mobilizing resources. In either case, the war should be over not later than the end of 1946.
On the other hand, we are unable to estimate the time required or the losses that will result in an effort to defeat Japan by isolation, blockade and bombardment without invasion, because of our inability to predict at what stage thereof the Japanese might concede defeat, and because of the possibility that invasion of the Tokyo area would ultimately be necessary. We feel that at best, such strategy would lead to a longer and probably more costly war.
9. In summary, our planned course of action is:
10. Russian participation in the war. In previous discussions and correspondence with the Russians they have indicated that they would probably require about three months after VE-Day for concentration of troops and supplies on their eastern front. We have considered that Russia’s entry at as early a date as possible consistent with her ability to engage in offensive operations is highly desirable to provide maximum assistance to our Pacific operations and that the primary objective of Russia's military effort should be to contain and destroy Japanese forces in Manchuria.
We believe that we can defeat the Japanese in the main islands regardless of Russian entry, because of our own estimated ability to restrict movement of Japanese reinforcements from Asia. However, the defeat of the Japanese army in North China including Manchuria would be a valuable contribution to the early and economical termination of the war.
As to basing U.S. forces in Russian territory, this is no longer considered necessary, and we therefore suggest that this subject be discussed only if necessary in connection with Russian discussion of opening a sea route to their Pacific ports.
Opening a sea route to Russian ports may well be a result-ant requirement of Russian entry into the war. We estimate that it might be satisfactorily accomplished by U.S. convoy of cargo ships in small groups without the necessity for our seizure of Japanese territory or of basing forces in Russian territory other than an advanced anchorage at Petropavlovsk and minor base facilities at the Russian termini. However, it should be noted that a more desirable plan would be to route the convoys through Tsushima Strait once it is under our control, thus avoiding the ice conditions of the northern straits. We should avoid by all possible means U.S. commitment to costly operations in the Kuriles-Karafuto area for this sole purpose.
In general, we believe that the best policy is not to press the Russians for further information or for any commitment, but merely to declare our readiness to receive and fully consider any proposals which they may wish to make.
11. Participation by other nations.
It is estimated that Japanese strength in China in the fall of 1945 excluding Manchuria, will be about 900,000 men. It is considered that the major share of of defeating the enemy in China south of Manchuria should fall to China.
Army: 1 Canadian division has been accepted for participation in CORONET. 3 Australian Imperial divisions are currently being employed in Southwest Pacific Area under U.S. command. The British Chiefs of Staff have recently proposed that 3-5 British Commonwealth Divisions participate in the final phase of the campaign in Japan, all to operate under U.S. command. The views of the Australian and New Zealand Governments on this proposal have been requested by the British Chiefs of Staff, but not yet received. The British intend deploying Commonwealth forces to the extent of 21 divisions and 16 brigades (probably including the above 3-5 divisions) in the Southeast Asia-East Indies area. Under separate consideration is an offer to the U.S. of 1 Australian division to participate in operations against Japan proper.
Air Forces: Negotiations are in progress to make use of 10 squadrons of British bombers in the Pacific, with a possible ultimate employment of 20 squadrons. Also a force of approximately 15 tactical squadrons have been offered for support of the 3-5 divisions indicated above. The RAF will provide air units found necessary for operations in Southeast Asia.
Naval Forces: Elements of the British Fleet will support operations in Southeast Asia; 3 naval assault forces, comprising amphibious lift for about 3 divisions, will be continuously available to the Southeast Asia Command, should these elements not be used in the main operations against Japan. The British Pacific Fleet, consisting of 4 battleships, 5 carriers, accompanying light naval forces and train, is currently operating under Admiral Nimitz. In addition, elements of the East Indies Fleet are offered for support of the 3~5 divisions proposed above.
Estimated Japanese strength in Southeast Asia and Malaysia, excluding the Philippines, in the fall of 1945, is about 600,000 men. The British should continue their primary responsibility for mopping-up the Japanese in SEA and the East Indies, exclusive of the Philippines. Acceptance of the latest proposed British Commonwealth contributions to the final phase of the war against Japan should not prejudice early accomplishment of this task provided the assault lift available to SACSEA is not employed elsewhere. The British Pacific Fleet, elements of the Royal Air Force, one Canadian division and possibly the Commonwealth force proposed by the British will participate in the operation for invasion of Japan. It is the intention of the Joint Chiefs of Staff to turn over to British command certain portions of the SWPAC area including Australia, the Solomons, New Guinea, New Britain, New Ireland and the Netherlands East Indies.
We believe that offers from any nation to contribute token or minor assistance in the Pacific war should be considered on their military merits. The acceptance of any forces should be on the bases that they are to be trained and equipped to meet U.S. standards of combat efficiency, can be effectively employed in planned operations against Japan, are reasonably self-supporting, and will operate as determined by the U.S.
12. Control and Command in the Pacific War .
Throughout previous staff discussions with the British we have taken the position that control, command and direction of the war in the Pacific lies with the U.S. The British thus far have committed their forces under this arrangement. We believe that we should continue to follow that policy and that any efforts which may be made to bring the direction of the Pacific war under the laborious, argumentative and time-consuming system of combined control should be vigorously opposed.