Planning Invasion of Japan (Kyushu Island)

by Dr. Hargis Westerfield, Division Historian


On 1 Nov. 1946, our 41st Division would be one of nine divisions assigned to start the first invasion of Japan. We were part of General Innis Swift's I Corps. Teamed with other veteran 25th and 33rd Divisions, we were to land on big Kyushu ("KOO-SHOO") Island. Based on south Kyushu 400 miles south of Tokyo, we were to defeat desperate large air-ground armies - then garrison that new staging area to overrun heartland Kanto Plain on Honshu Island and capture Tokyo.

For Yanks and Japs, this Kyushu invasion might be the most important operation of World War II. It might have quickly ended the war. On Kyushu, Japs would surely have expended most of their kamikaze planes - really their crucial defense line. If their Kyushu defense had failed - it would be limited to 10 days' battle - they might have sued for peace to avoid the occupation of Tokyo.

For we did not need to occupy all Kyushu's 16,000 square miles. We planned to hold only a strip averaging 100 miles wide east and west by 80 miles north and south on the lower end. There would be a roomy seaside base for attacks on the heartland Kanto Plain with Tokyo.

Our nine divisions would find this strip easy to hold. Kyushu was mostly a mountain massif 80 miles wide. The national highway around the southeast coast was mostly a single two-lane gravel road. Inland secondary roads were for light traffic, single-laned, from which ran narrow dirt tracks. Single-tracked coast railroad had many bridges and tunnels readily smashed by our planes. Kyushu Japs would not expect reinforcements from the defense of Tokyo.

We had two great naval forces with carrier planes and two land-based air forces to land our infantry on Kyushu with minimum casualties. These four forces were necessary against Jap suicide pilots.

Fleet Admiral W. F. "Bull" Halsey's 3rd Fleet would strike first. Including a British task force, Halsey had 17 fleet and escort carriers, eight battleships, 20 cruisers, 75 destroyers, and necessary support vessels. For 67 days, to 23 October, 3rd Fleet would damage Jap air forces, and disrupt passage between Honshu and Kyushu. Eight days before D-Day, 3rd Fleet's carrier groups would join with carrier groups of Admiral R. R. Spruance to soften up the Kyushu landing area.

Spruance's 5th Fleet had a Fast Carrier Force of seven fleet and three light carriers, with an Escort Carrier Force for closer support. It also had a Gunfire and Covering Force, a Mine Force, and three Amphibious Forces - these three under one commander.

Two land-based Army Air Forces would also strike. Beginning 23 October, Lieutenant General G. C. Kenney's Far Eastern Air Force would cut communications from north Kyushu to the assault area. They would collapse strategic bridges, and cut rail lines to areas for reinforcements from seaport bases like Nagasaki and Sasebo. With B-29s and B-32s, General C. A. Spaatz's Strategic Air Force would mine straits between Honshu and Kyushu.

Eight days before we landed, Spruance's 5th Fleet would charge the shores. While carrier planes controlled the air, 16 escort carriers would soften up the beach approaches. Surface fire support groups would bombard to cover our fleet of minesweepers who would drag the inshore waters over and over again. Five days before we landed, underwater demolition teams would clear the underwater defenses and Japanese frogmen crouched below the surface.

On 1 November 1946, nine Infantry Divisions, including our 41st and three Marine Divisions would beachhead on southeast Kyushu. For security reasons, however, four Regiments must first seize' outlying islands, 4-5 days before the nine divisions would hit the Kyushu mainland. On 27 October, 40th Division's three Regiments and 158 Infantry would capture offshore islets south of Kyushu - for unsinkable bases for radar and fighter stations to protect our landings. At Okinawa, too many out posting destroyers had died under kamikaze swoops.

Five days later, on 1 November 1946, three Corps of three divisions each would attack Kyushu on a shore front roughly in a half-circle 150 miles long from near Kagoshima on the west to Miyazaki on the east.

On the west, Marines of 2nd, 3rd, and 5th Divisions would strike, and on the far east, Army I Corps would beach with our own 41st Division. Most of the 150 miles were narrow beaches under heavily fortified cliffs. Behind them were two wide bays, Kagoshima Wan and Ariake Wan. Past the cliffs were excellent airports - among them, Kagoshima, Chiran, and Miyakonojo - which last the 41st might have to take.

North of Ariake Bay were long white beaches with the widest plain land in all south Kyushu. Here our 41st would land.

On the far west, the three Marine Divisions would have the strongest Jap force to battle-three Infantry Divisions, an Infantry Brigade, a tank Brigade and a whole Artillery Command. The Marines had to capture the western Kagoshima Bay shores, consolidate and move north.

East of the Marines, XI Corps (43rd Division, Americal Division and 1st Cavalry Division would secure the eastern shore of Kagoshima Bay and Ariake Bay. Farthest east and north, our 41st Division would hit Miyazaki Beaches as part of General Innis Swift's I Corps, with 25th and 33rd Divisions. We would fight the Japs' 154 Division straddling Miyazaki City, and 212 Division on the north and 156 Division on the south. We had two missions. We had to turn south to overrun Miyakonojo Strip. We also had to turn north and come up on line with XI Corps and the Marines in the mountains to cordon off south Kyushu from north Kyushu attacks. (If not needed elsewhere, three days after these troops beached, IX Corps - 11th Airborne, 98th and 81st Divisions would reinforce the Marines and XI Corps.)

Now this was the Miyazaki battlefield for our 41st Division. Foreshore were two different beaches, both 750-1000 yards long. Behind each beach was a mile-long lagoon. Oyodo River separated those beaches. Miyazaki City of over 100,000 people was near Oyodo Mouth.

Oyodo River was deep enough for LSTs a few miles up, but tracked vehicles were needed to cross the two beaches and the lagoons behind them. Behind North Beach were rice paddies impossible for tanks without help, and miles of guns emplaced above this beach. Mortars and automatic weapons pits guarded South Beach from the hills. Yet past the heavily defended beaches was a plain where our armor could fight the Japs.

The corridor south to Miyakonojo Air Field would be hard to fight through. There was only one road through mountains with many tunnels and bridges. Such was the 41st beachhead near Miyazaki in eastern Kyushu.

 

Japanese Defense Plans.

Japanese defense plans certainly sounded formidable. Because of the kamikaze menace, air defenses were the most powerful, but we could also fear a Navy-Army surface fleet of small suicide craft, and big guns in caves. Finally, regular Infantry Divisions and Coastal Defense Divisions would hold the beaches or fill them with their dead.

By dawn on D-Day, a four-fold air attack would swoop from the air. While our advancing fleet was still in the open seas, 2,000 Army Navy fighters would battle for air superiority over Kyushu. A special force of 330 Navy pilots would strike our main body to hold it from using their guns and planes to protect their transports. With those two forces already in battle, a third force of 825 kamikazes would bomb our 180 personnel transports and 70 supporting ships. Near our night's transports' anchorages, we'd be struck by 2,000 more kamikazes in waves of 2-300, hour by hour.

How successful would these air attacks be? Based on Jap estimates of their results in the Okinawa Operation, they expected up to 50 percent losses on us. But these estimates erred. They thought that they had sunk 196 ships. Actual number was 35 sunk, with 31 more heavily damaged. Yet the kamikaze attacks at Okinawa did sink about five times as much as non-suicide attacks of trained flyers did sink.

The Japs also hoped to defeat our invasion because they had thousands of planes to fight over a short distance for a long time. They noted that our land-based planes would have to fly back 350 miles to Okinawa to rearm and refuel. Our Navy planes and AckAck guns would be left to fight without land-based help. Continuous fire would cause our Navy weapons to malfunction. Battle fatigue would exhaust their crews by darkness. And all night and nine more days afterwards, the remaining Jap planes would smother and sink our fleets.

(But surely our air force Generals Kenney and Spaatz had foreseen Japanese plans to wear us down by sustained attacks day and night. Kenney and Spaatz would surely have organized their flights of planes in stages from Okinawa to keep on target day and night.)

The nearly destroyed Japanese Navy could have almost no part in resisting invasion. But it did produce the suicidal "kaiten," a midget submarine which had potentials. It was a modified "long lance" torpedo manned by a pilot. Launched under water from submarines, kaitens had sunk a U.S. tanker and damaged two transports in early 1945. But only 450 kaitens were ever built.

Both Navy and Army had suicide motor boats. Essentially, they were light plywood craft 18 feet long with automobile motors, maximum speed 25 miles per hour. With a bomb of about 500 pounds in the bow, a sailor was to crash a vessel wherever he could hit it. With two depth charges on each side of the cockpit, the soldier was to target the vessel's engine. Both soldier and sailor would get quick deaths.

With jagged shores, the south Kyushu coast was made for fire on our ships - front, flank and rear. For example, Ariake Bay was guarded by 18 heavy or medium cannon in caves or behind embankments. There were four 280 mm howitzers, four of 240 mm, two 120 mm guns, and eight 100 mm guns with the lighter divisional pieces of 86th Division. Where our 41st Division would land near Miyazaki, seven 150 mm guns would strike us-along with reinforcements from more heavy field artillery units.

Even if U.S. forces did beach, close combat would redden the sands. First, massed "coastal combat divisions" would jam the beaches to fight to their death. Secondly, unleashed "line divisions" would charge in over the bodies of coastal defense divisions.

Evidences of Japanese desperation were these "coastal combat divisions." With fewer fighters than the regular line divisions, they had superior fire power. They would have many machine guns, grenade launchers and knee-mortars. Yet they were almost immobile, with only a fourth of the horses and vehicles of the regular line divisions - and only to forward rations and ammo. Deployed in caves and bunkers, they would charge to strike our Infantry as we hit the beaches. Greatest drawback was that their personnel were poorly trained civilians.

But Jap line combat divisions were the decisive reserves. They would charge into battle as soon as the coastal divisions were committed. Infantry, tanks and heavy field artillery would attack even over the screaming wounded and corpses of the coastal divisions. Jap line divisions and coastal divisions would be so tightly compacted in struggle that our Navy and planes would be unable to find Jap targets because they would fear to kill our Infantry hitting the beach.

At all costs, the Japs planned to hold us at the water's edge. If we could dig in on the beaches, our field artillery and flame-throwing tanks would clear our way to the mountains bordering their coastal plains. Our thick-armored tanks with 75s or 105s would outrange and gut their tanks. If we reached the foothills to entrench, their Infantry would lack the power to overrun our lines. Yet all of their largest air fields lay on or near the coast plains; they had to die holding them.

Such were the U.S. offensive and Jap defensive plans for "Operation Olympic," our name for the Kyushu invasion. The Japanese evinced their desperation by marshalling enormous air and ground forces. For some historians, it seems that the Kyushu battles would have been the only battles in the Japanese home islands. The slaughters on both sides would surely have caused negotiations for peace - if only to forestall a Russian invasion from the north.

We are absolutely certain of just two truths. First if our 41st had fought on Kyushu, there wouldn't have been much left of our Division. Second, we are happy that no Japanese or Americans were killed or wounded in Operation Olympic that unfought Battle of Kyushu. No blood was spilled on Miyazaki Beaches!

 

CREDIT: Discoveries of new documents about our Jap invasion has led to my total revision of this history. Most important was the study of U.S. battlefields from General E. J. Winslett's 17 -page typescript, "Defense of Southern Kyushu" (KOO-SHOO), dated 3 June 1946. Other documents now used were Richard O'Neill's book Suicide Squads (New York: Ballantine Books, 1984); and James Martin Davis' Top Secret/ The Story of the Invasion of Japan (Omaha, Nebraska: Ranger Publications, 1986). (AT-163's George Philip Morris supplied this last brochure.) Two more books were Professor K. J. Bauerle's "Olympic," in Marine Corps Gazette (August 1965); and Lee Enderlein's "Greatest of All Invasions," in Military History (August 1985). (Irwin Soliday of 163 Infantry sent me this publication.)

In this new history, I have still included citations from my earlier unpublished history. Most important were two magnificent volumes: Reports of General MacArthur: Japanese Operations in the Southwest Pacific Area, printed in 1950. Okinawa background of kamikazes I found in Samuel Eliot Morison's Victory in the Pacific, Vol. XIV of his History of United States Naval Operations in World War II. (O'Neill's Suicide Squads is a small, carefully documented encyclopedia of Italian, German, British, and Japanese plans, diagrams, and operations of kamikazes, land, sea, and air.)