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What if the United States Had Invaded a Japanese Home Island?

By Mark Grimsley
3/8/2018 • World War II Magazine

In mid-1941 Adm. Isoroku Yamamoto, commander in chief of the Imperial Japanese Navy, predicted that if war broke out with the United States, “I shall run wild considerably for the first six months or a year but I have utterly no confidence for the second and third years.” He knew it wouldn’t be enough to seize the American possessions of Guam, the Philippines, and Hawaii, or even a main land city like San Francisco. “To make victory certain,” he warned, “we would have to march into Washington and dictate the terms of peace in the White House.”

These comments are quoted in nearly all histories of the Pacific war because they encapsulate the unlikelihood of any plausible scenario in which Japan could prevail against the military and economic might of the United States—or undercut American will sufficiently to achieve a negotiated peace settlement. The difficulty of imagining a Japanese victory extends even to Rising Sun Victorious: The Alternate History of How the Japanese Won the Pacific War, a volume of essays edited by Peter G. Tsouras.

Judging by its title, one would suppose that the 10 contributors to Rising Sun Victorious offer 10 distinct avenues to Japanese victory. But six postulate merely operational, not strategic, success. Japanese triumphs in the battles of the Coral Sea, Midway, and Guadalcanal, for example, provide only temporary respites before American shipyards and aircraft factories produce new armadas with which to resume the contest. And of course, nothing the Japanese could have done would have had any effect on the development of the atomic bomb. (One contributor notes that even if the United States had lacked bases from which B-29s could carry the bomb to Japan, it still could have relied upon a crash program to produce the Northrop XB-35 Flying Wing, a heavy bomber with a range of over 8,000 miles.)

The four alternate histories that do lead to victory actually yield only compromise settlements with the United States. Of these, perhaps the most intriguing is the volume’s final essay—“Victory Rides the Divine Wind: The Kamikaze and the Invasion of Kyushu,” by D. M. Giangreco, a former editor at Military Review who has written extensively on American plans to invade Japan—in which a military dis aster has forced the United States to conclude an armistice with Japan. What had gone so terribly wrong?

In Giangreco’s account, the abortive military coup by aggrieved Japanese staff officers on August 15, 1945, succeeds, and—despite the atomic bombings of Hiroshima and Nagasaki, as well as two other nuclear attacks on unnamed cities— the Japanese military fights on. The Americans have little choice but to continue with Operation Olympic, their plan for the invasion of Kyushu, the southern most of the Japanese home islands. The invasion, scheduled for November 1, 1945, is postponed until December 10 after a major typhoon ravages the American fleet in October. (A typhoon packing 140 mph winds actually did occur, on October 9, 1945.) The typhoon strongly echoes the famous storms—“divine winds”—that swept away two Mongol invasion fleets in 1274 and again in 1281, and creates a propaganda coup for the Japanese militarists that further cements their authority.

When the 2,800-vessel American invasion fleet finally appears off the coast of Kyushu, it is beset by another typhoon of sorts. This one is composed of more than 12,000 Japanese Special Attack Corps air craft, manned by pilots with instructions to ram their bomb-laden planes directly into American vessels: the notorious kamikaze, or “divine wind,” craft, a reference to the infamous typhoons of centuries before.

Historically, the first kamikaze attacks took place on October 25, 1944, as part of the Japanese defense of Leyte Island in the Philippines. During the Battle of Okinawa in April 1945, waves of over 2,000 kamikaze aircraft attacked the American fleet, sinking 34 Allied ships and damaging 288 others. Despite such losses, however, American naval planners believed that they had created effective countermeasures against suicide attacks, most notably through the use of destroyer picket screens that provided early warning of incoming kamikaze formations.

In Giangreco’s scenario, however, the kamikazes attacking at Kyushu, able to take off from airfields close to the fleet and emerge at low altitude with minimal warning time, prove devastatingly effective. And the scale of the attacks is far greater than American planners anticipated. Some 12,000 kamikaze aircraft are involved, overwhelming the defenders and sinking dozens of transport ships with a loss, in Giangreco’s scenario, of 29,000 Americans, most of them ground troops. The aerial attacks are supplemented by suicide strikes from fast, explosive-laden motorboats that ram American vessels.

These attacks disrupt the intricately planned amphibious assaults. Without proper resupply and reinforcements, the progress of the American divisions that do get ashore is badly delayed. As a result, in two weeks American casualties exceed 170,000 dead, wounded, and missing. An additional 40,000 casualties arise as a result of radiation sickness, an unintended consequence of the atomic bombs used to destroy Japanese units en route from northern Kyushu to the invasion sites on the southern part of the island.

Nor do American problems end there. As Giangreco notes, the invasion of Kyushu was intended as a preliminary to Operation Coronet, an even larger invasion of Tokyo’s Kanto Plain on the island of Honshu, scheduled for March 1, 1946. But the six week delay in launching the Kyushu invasion would place Coronet directly in Japan’s annual monsoon season; that, coupled with American reversals at Kyushu, would have jeopardized construction of the 11 airfields needed to support the Honshu invasion.

Moreover, the radiation casualties sustained on Kyushu would have forced a halt to plans for the use of tactical nuclear strikes—one bomb for each American corps sector—directly on the Coronet invasion beaches to eliminate the defenders. Operation Coronet, therefore, becomes impracticable.

Giangreco bases his account on the historical fact that the Japanese had managed to pack Kyushu with 12,735 kamikaze air craft: more than twice the number American intelligence had anticipated. He also points out that amphibious invasions were complex, carefully choreographed affairs in which the substantial loss of transport and support ships would have created massive disruptions ashore. For example, the supply of whole blood and blood plasma for the Kyushu invasion was to have been concentrated on just five LST(H) vessels, one for each of the invasion beaches. The loss of any of these (in Giangreco’s account, two are sunk) would have resulted in the deaths of hundreds of American wounded who might otherwise have survived.

And as for the use of atomic bombs, Gen. George C. Marshall had advocated their use in support of the Kyushu invasion and the invasion of the Kanto Plain. Since American physicists badly underestimated the extent of radiation sickness caused by atomic explosions, it is likely that as many as 40,000 American troops might have fallen ill from bombs intended to destroy Japanese reinforcements.

Nonetheless, in Giangreco’s account the nuclear attacks succeed in bringing the Japanese to the conference table. Willing to endure the loss of cities, they cannot bring themselves to see their army—unable to put up an “honorable fight”—vaporized by a rain of atomic bombs. The Americans have second thoughts of their own when it becomes clear that American casualties in a continued invasion would exceed the number of troops available to replace them. The Allies and Japan therefore agree upon a compromise peace settlement. Giangreco is not specific about the details, but it would surely have involved an unequivocal guarantee that the Japanese emperor would remain in power and, most likely, mean no military occupation of the Japanese home islands.

It seems odd to include this scenario in a book ostensibly about Japanese victory, for the sequel to such a settlement would have been unmitigated disaster for the Japanese. In reality, the emperor remained on the throne anyway, and only American occupation saved Japan from famine, restored its shattered economy, and created a new political order that made the Land of the Rising Sun a land of peace and prosperity in the decades that followed. A “divine wind” that saved Japan from the humiliation of unconditional surrender would in fact have been an ill wind that brought only calamity.


Originally published in the March 2009 issue of World War II. To subscribe, click here

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