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HOME > JAPAN > INVASION PLANS

Olympic vs. Ketsu-Go (part 3)

continued from part 2

Task Force 41, Adm. Turner's Advance Force, would arrive off the objective on X-8 in company with TF-58, Adm. Sherman's Fleet carriers. While the carrier planes maintained command of the air in the objective area, those from Adm. Durgin's 16 "Jeep" carriers would begin softening up the beaches, attacking defenses, and preventing reinforcements from reaching the area. At the same time the fire support groups would begin their bombardments and cover Adm. Sharp's sweepers as they plodded back and forth, sweeping and check-sweeping. On X-4 (27 October) the UDTs would begin clearing the seaward defenses. Thus the plans called for little change from the pre-invasion pattern worked out so painstakingly and successfully during the preceding three years.

Off Ariake Wan 6 old battleships, 6 cruisers, 13 destroyers, and 34 support craft under Radm.. R. L. Conolly drew the mission of eliminating the batteries on Toi Misaki, Hi Saki, and along the shore of the bay. Conolly would also eliminate the suicide boat and submarine pens at O Shima, Odatsu, and Biro Jima, as well as the seaplane bases near Sakida and Odatsu. Once these preliminary targets were removed the force could concentrate on the defenses along the beaches at head of the bay over which Lt. Gen. C. P. Hall's XI Corps would land.

Further north Radm... I. N. Kiland's 3 old battleships, 8 cruisers, 11 destroyers and 35 support craft would eliminate the batteries near Tozaki Hana, the suicide boat lairs south of it, and the seaplane bases at Hososhima and Miyazaki. A second assignment called for shelling of the rail junctions at Tsuma Jogasaki, and Tsuno to prevent southward movement of reinforcements. Having accomplished its initial mission, Adm. Kiland's force could then concentrate on clearing the beaches near Matsuzaki across which the Seventh 'Phib would land Maj. Gen. I. P. Swift's I Corps.

Probably the most difficult softening up job fen to Radm... Jerauld Wright. With only 4 old battleships, 10 cruisers, and 14 destroyers and 74 support craft he had the dual responsibility of smashing the defenses both in the Koshiki Retto and along the beaches between Kushikino and Kaminokawa. Specifically mentioned in Adm. Wright's orders were batteries at Noma Misaki and Hashima Saki, the Kushikino airfield, and the Akune seaplane base. Wright's vessels were also to interdict the Akune-Kushikino road and railroad as well as softening up the beaches for Maj. Gen. Harry Schmidt's V Amphibious Corps. Wright's force also was responsible for covering and supporting the invasion of the outer islands by Radm... G. B. Davis's Western Attack Force TF-42).

Plans drafted in April 1945 called for main fronts in the Pacific and the East China Sea, with emphasis on operations, as always, in the Kanto and Kyushu regions. Strategic locations on the Japan Sea coast must be defended to the maximum, and American maneuvers in those waters blocked. US air assaults must be countered, and the capital and key points protected-especially centers of production, operational preparation, and communications. Again it was stated that invasion attempts should be thwarted on the high seas if possible. Main targets should be transport convoys. Exploiting the special features of the terrain, the Japanese ground forces must heroically attack enemy forces that did land, although Japanese air support might not be available. Even if enemy elements penetrated inland, resistance must be continued and domestic security maintained.

In June, IGHQ established a Tokyo Defense, Army, with the mission of defending the district centering around the Imperial Palace. Against [this?] direst possibility, the Army tentatively decided upon a site for a provisional Imperial Palace to be located in the suburbs of Nagano city, in the direction of the Sea of Japan. A large-scale Imperial General Headquarters was in the process of secret construction in caves at Matsushiro, in Nagano prefecture, from 1944. The Government itself, however, decided that Tokyo had to be defended to the last. An immense position construction program was studied, largely as a political gesture.

Since the capitulation of Germany and the deterioration of Japan's overall position, acquisition of intelligence concerning Allied intentions grew increasingly difficult for the Japanese. Yet by July 1945 it became imperative to draft a new estimate of the situation. Using whatever information was available to them, the Japanese revised their earlier judgments. Operational evidence was helpful: Enemy attack and reconnaissance planes were most active over Kyushu, while the Bonins bases appeared quiet. It was now thought that the Americans would not invade Kyushu and Shikoku until after late September when the typhoon season was over. US bases of operation would meanwhile have been expanded or set up in the Ryukyus, Amami Oshima, and other nearby islands. Once major air and naval installations had been established in Kyushu and Shikoku, etc., the Americans could be expected to land in the Kanto region and seek a showdown in the spring of 1946, after redeploying the necessary forces from the European theater. Diversion or feints could be anticipated in the regions of Hokkaido and the Tohoku.

Although the preceding judgment represented a significant modification of the April estimate (it now being the view that the Kyushu invasion would precede the Kanto landings, and that the latter would not materialize until the next year), there was by no means unanimity concerning details and alternatives. Some felt that Japan's disintegrating posture might encourage the enemy to press straight to the Izu islands and land in the Kanto area by the late autumn of 1945, in one fell swoop. Or, if the Americans judged that defenses were too far advanced in the Kyushu and Kanto areas, they might even try to split the homeland by pushing from Ise Bay against the Nagoya and Kyoto-Osaka-Kobe sectors. Elements might possibly dare to penetrate the Korea Strait and land on the Japan Sea coast of Honshu.

A number of Japanese planners were of the opinion that the Americans might first strive to isolate the home islands from the Asian continent, setting up springboards in central and north China, as well as South Korea, before striking into the Japanese homeland. Not unreasonably, it was believed that the Americans might tighten their aerial and naval noose around Japan, intensifying and protracting the surface and underwater blockade and the incendiary bombing campaign. At that point, reeling Japan might be given a surrender ultimatum which, upon rejection, would be followed by simultaneous landing operations various key points.

A total of 60 American divisions, richly endowed in artillery and armor, were expected to be committed to the landing operations against Kyushu and the Kanto district, with all-out strategic and tactical support by the US Navy and Air Force. Airborne units would probably be employed, especially against Kyushu from Okinawa.

Since May and June 1945, IGHQ and the General Army Headquarters had come around to the point of view that the way to win was not to fall back from the coast after the invaders had got past the suicide planes and ships and the coastal batteries. Instead, the enemy must be engaged in decisive battle on the beaches and in the all-important coastal zones. The foe must not be given the time to consolidate the beachheads; he must be attacked unrelentingly, lest he dig in.

The occupation of Kerama Retto during the Okinawa campaign had proven the tremendous advantages to be gained from securing a nearby offshore base before the start of a major landing. Koshiki Retto off the southwestern tip of Kyushu offered a similar opportunity and the OLYMPIC Plan called for its seizure by Bgen. D. J. Myers's 40th Infantry Division beginning on X-5 (27 October).

Western Attack Force also drew the assignment of landing elements of Myers's division on the outer islands of Uji Gunto, Kusakaki Shima, Kuro Shima, and Kuchinoerabu Shima, also starting on X-5. The seizure of these islands would clear the sea lanes to the Kushikino beaches. Even more important, they provided sites for the early warning radar and fighter director stations necessary to protect the assault forces and beachhead from the heavy kamikaze attacks. On X-4 Davis's vessels would land the bulk of the division of Kami Koshiki, Tama Shima, and Shimo Koshiki. This would permit the doughboys to clear the defenders from Nakakoshiki Wan and Nakagawara Ura and allow their use as an emergency anchorage and seaplane base.

The plans contained one contingent operation. It provided for the landing of Bgen. MacNider's 158th Regimental Combat Team on Tanega Shima on X-5 or later if necessary to eliminate Japanese interference with the sweepers clearing Osumi Kaikyo. If the RCT was not needed there, Radm... R. P. Briscoe's Southern Attack Force (TF-44) would put the force ashore on Kyushu as reinforcements after X + 3.

Most of the troops assigned to OLYMPIC were in the Philippines although the Marines were to mount out of their bases in the Marianas and Hawaii. All three Amphibious Forces were to stage rehearsals, the Third and Seventh in the Philippines and the Fifth in the Marianas.

The wide dispersal of the landing areas caused one change in amphibious doctrine. The plans did not call for a simultaneous assault by all major forces. Each attack force commander was to set his own landing time independent of the others. How great the difference in landing hours would have been we do not know as they had not yet been set when planning ceased.

In the light of what is now known about the details of the American landing plans, it is of interest to note the sites which the Japanese themselves had thought would be invaded. It was clear that the Americans would want major air and naval bases in southern Kyushu, especially in view of a subsequent operation against the Kanto region. Southern Kyushu was particularly vulnerable to an attack from Okinawa, and the installations were excellent: air bases at Kanoya, Chiran, Miyakonojo, Nyutabaru; airfields at Miyazaki, Kokubu, Kogoshima, Izumi; naval bases in the bays of Kagoshima and Ariake. At first there was some thought that northern Kyushu might be attacked, after Cheju-do and the Goto islands had been seized by the Americans; but later it was felt that southern Kyushu would probably receive main attention.

As for debarkation points, there were three likely coastal sites: Miyazaki prefecture, Ariake Bay, and Satsuma peninsula. Until May 1945, the major enemy effort was expected in the region of the Miyazaki Plain, but later priority was accorded Ariake Bay. Airborne raiders could be anticipated at the airbases at Kanoya and Miyakonojo. Enemy fighter and naval springboards might be set up at Tanegashim beforehand; less likely at Koshiki.

In conjunction with an invasion of southern Kyushu, some American diversionary units would probably be landed on Shikoku island-on the

Tosa Plain in particular, and at Sukumo Bay in the southwest.

If the enemy forces did attack northern Kyushu, they could be expected to commit even more powerful strength than was hurled against south Kyushu. The main body would land on the Fukuma coast east of Hakata, elements in Hakata Bay and in the Shimonoseki-Moji sector. Beforehand, Cheju-do and the Goto islands might be taken, and Tsushima-Iki neutralized.

continued in part 4