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Olympic vs. Ketsu-Go (part 2)

continued from part 1

The intelligence experts correctly predicted a strong defense. They estimated 450,000 men on Kyushu with 220,000 of those (including five field divisions) south of the line Minamata-Nabeoka. An additional three or four divisions were believed available in the northern part of Kyushu as reinforcements while a small additional force could be committed from Honshu. Intelligence estimates, however, predicted that few troops would be committed from Honshu in order to conserve them for the defense of the main island.

By March 1945 the General Staff had completed an outline for the defense operations (coded as KETSU-GO). All homeland area armies were directed to send their chiefs of staff and key officers to examine the draft informally in Tokyo. Exploiting the terrain of the home islands, and exhorting the fighting spirit and cooperation of the 100 million Imperial subjects, all Navy and Air Force remnants were to tackle the special-attack mission of destroying enemy forces while still at sea. But since Japanese naval power was almost destroyed, and the air units were so weak, homeland ground formations (deployed in depth and massed in decisive battle sectors) would take the offensive against enemy troops who managed to land, and would "recoup in one stroke the declining fate of the Nation."

Emergency defense preparations must be accomplished between April and July 1945 (completed by early June in the case of Kyushu and Shikoku). Reinforcement would be effected in the second stage, August-September; and the plan would be completed thereafter. Provision would be made to rush reinforcements to main landing theaters, whether Kyushu or Kanto. In anticipation of enemy disruption of the transportation system, the troops were essentially to move on foot, which meant that planning factors had to be protracted, although enemy landing operations could be expected to be carried out swiftly. For example, it might take 65 days to move Japanese divisions from Kyushu to the Matsumoto-Nagano sector, and another 10 days to deploy them.

Formation of new ground divisions proceeded apace, under the goad of imminent invasion, while elite divisions and the last armor in the Kwantung Army were recalled from Manchuria.

The fixed defenses on Kyushu were expected to be formidable. Not only were the landing areas themselves well defended but the island's terrain was mountainous and deeply scarred by numerous narrow and steep stream beds. Thus it was the type of terrain which particularly lent itself to the defensive tactics at which the Japanese had proven themselves so adept.

In April, IGHQ directed changes in its homeland command system, although the Army was never able to achieve unified command of all ground operations, even during operational preparations, because of Navy opposition. A 1st General Army was formed at Tokyo, under Field Marshal Sugiyama, covering eastern Japan, and including three area armies (exclusive of Hokkaido, under direct IGHQ control). A 2nd General Army was established at Hiroshima, under another field marshal, Shunroku Hata, to cover western Japan and Shikoku, utilizing two area armies. Lastly an Air General Army was set up in Tokyo, under General Masakazu Kawabe, to command three air armies. The United States forces, the main enemy, were to be defeated in decisive battles in strategic zones of the homeland, especially in Kyushu and Kanto. Hundreds of air squadrons were in process of being fitted out, mainly fighters. In addition the suicide air units were being rushed into shape. By the end of June, some 2,000 suicide aircraft had been produced.

The Navy estimated that it would have to face as many as 50 large submarines but no major surface units. The American intelligence experts recognized that the southern Kyushu coastline lent itself to the use of suicide craft and their studies of photographs and other information led them to conclude that the coastline would be dotted with midget submarine and suicide boat lairs.

After the defense of Okinawa collapsed in the spring of 1945, the Japanese began to fear that the "jubilant" Americans might assault Kyushu directly, before the lagging defense preparations had made much progress. Even at vital Ariake Bay, only 50% of the projected construction was ready, and the percentage was far lower elsewhere. Along the coasts of Kyushu, a mere 4 1/2 ground divisions were in place by now-poorly trained, ill equipped. Headquarters were not ready, troops were still en route, ammunition was being assembled. The situation was much the same in Shikoku island, and little better on the Kanto front, where 7 1/2 divisions were on the coast, working on defenses.

Judging that there was now little likelihood of an immediate attack from the Aleutian area against northeast Japan, IGHQ decided to withdraw strength from the Hokkaido region and transfer it to Honshu and Kyushu. In late May, operational preparations in the Kanto area were temporarily suspended, and all available rail transportation was diverted to the buildup southern Kyushu. Units made up of untrained or old reservists were deployed prior to being fully equipped. Even bayonets were in short supply, a and mortars had to be substituted for artillery. The rationale was that harmony among individuals was more important than weapons themselves. But a hard-headed Japanese military critic commented that if the Americans had attacked southern Kyushu in June or July 1945, the country would have found itself in a critical situation.

Japanese Intelligence was reporting no evidence of an early American invasion of the homeland, and the Army began to expect no landing attempts against the main islands before October 1945-which was an immense source of reassurance. The dogged resistance at Okinawa was thought to have purchased time for the homes defense buildup, and the outlook in Kyushu brightened a bit.

In the spring of 1945, IGHQ was of the opinion that after the end of the Okinawa battle, American forces would attempt landings at key places along the Chinese coast, in the Korea Strait, and on islands near the Japanese homeland. These springboard operations might occur sometime in the summer. Subsequent landings in the Kanto area (or, alternatively, first in Kyushu and then in the Kanto) would most probably take place after autumn.

The land forces available for a November assault were almost exclusively those already in the Pacific. Substantial reinforcements were en route from Europe but they would not arrive in time for the Kyushu landings. Their assignment would be to form the major portion of the forces destined for the Honshu landings in the spring of 1946. The same, of course, was not true of naval vessels since many European veterans already had been bloodied at Okinawa.

Some 2,902 ships and craft, not counting those temporarily assigned to the service squadrons, would make up Adm. Spruance's Fifth Fleet. Organizationally, it consisted of five major forces:

TF-40 Amphibious Force (Adm. R. K. Turner) consisting of TF-43, Third Amphibious Force (Adm. T. S. Wilkinson); TF-45, Fifth Amphibious Force (Vadm.. H. W. Hill); and TF-47, Seventh Amphibious Force (Vadm.. D. E. Barbey);

TF-54 Gunfire and Covering Force (assigned to Vadm.. J. B. Oldendorf in the plans but he was hospitalized as a result of injuries received in the 12 August torpedoing of USS Pennsylvania);

TF-55 Escort Carrier Force (Radm.. Calvin T. Durgin) for close air support;

TF-56 Mine Force (Radm.. Alexander Sharp);

TF-58 Fast Carrier Force (Vadm.. F. C. Sherman), two groups containing seven fleet and three light carriers.

The notable feature was Adm. Turner's direction of all three Pacific Amphibious Forces. Never before had the three participated in a single assault.

Adm. Halsey's Third Fleet consisted of Vadm... J. H. Towers' Second Carrier Task Fleet (TF-38) and Vadm... H. Bernard Rawling's British Carrier Task Force (TF-37) and the usual collection of supporting vessels. In aggregate, Third Fleet could muster 17 fleet and light carriers, 8 battleships, 20 cruisers, and 75 destroyers. Some conception of the fleet's power can be formed from its record of 10,000 sorties in the month before Japan's surrender.

Third Fleet as the force assigned the task of softening up the objective area and isolating the battlefield would strike first. Between X-75 (28 July) and X-8 (23 October) the British and American fliers and gunners would attack widely scattered targets in the Japanese home islands in order to inflict the maximum damage on the Japanese air forces, disrupt communications between Honshu and Kyushu, and eliminate as much as possible of the remaining Japanese navy and merchant marine. Part of this effort would be diversionary British strikes on Hong Kong and Canton on X-45 (18 September) and X-35 (28 September).

Between X-14 (18 October) and X-8 Third Fleet would concentrate on aircraft, air installations, and shipping in and around Honshu, Shikoku, and Kyushu in order to isolate the assault area and divert Japanese attention. On X-8 two of Halsey's carrier groups would join Spruance's fliers in softening up the landing area while the rest of Halsey's force continued pounding more distant targets.

In general, Halsey's forces were restricted to operations east of a line drawn from Kinosaki on the north coast of Honshu, along the railroad through Wadayama to Himeji, and thence to the eastern tip of Shikoku. Targets to the west of that line and diversionary strikes along the Chinese coast were the responsibility of Gen. G. C. Kenney's Far Eastern Air Forces (Fifth, Seventh, and Thirteenth Air Forces, and 2nd MAW). In their attacks after X-10 (22 October) Kenney's men would pay particular attention to cutting, communications between the assault area and northern Kyushu. The key points in this effort would be the destruction of bridges near Mimitsu, Hitoyoshi, and Yutsushiro. At the same time the plans directed Kenney's aviators to cut the road and rail lines leading to the potential staging areas for reinforcements and counter-landing forces-Sasebo, Nagasaki, Omuta, Kumamoto, Oita, and Nobeoka. Following the landings Kenney's forces would move to Kyushu as fields were built or seized and once enough planes had arrived to support operations ashore, the Air Forces would assume responsibility for air support from the Navy.

Loosely tied to Operation OLYMPIC were the B-29s and B-32s of Gen. C. A. Spaatz's Strategic Air Forces. Air Force doctrine limited their use to "strategic" targets such as specified installations in Kyushu, the mining of Shimonoseki Strait, and after X-30 (2 October) the isolation of the Ningpo-Chusan area in China to prevent reinforcements reaching Kyushu from the mainland. An emergency provision provided for direct support by Lt. Gen. N. F. Twining's Twentieth Air Force from the Marianas-if directed by the Joint Chiefs of Staff.

continued in part 3