Yesterday was the anniversary of the dropping of the atomic bomb on the Japanese city of Hiroshima. In America, this means we have engaged in our annual tradition of debating whether or not using the bomb was the right thing to do. I've mentioned in the past that I abhor the existence of nuclear weapons and dearly wish that they vanished from the face of the Earth, but I'm not among those who believe that dropping the bomb was the wrong thing to do. What I want to talk about in this piece is the alternative choice that the Allies had to dropping the bomb: an invasion of the Japanese Home Islands.
By mid-1945, the war in Europe was wrapping up as the Americans, British, French, and Soviet armies swept through Germany and closed in on Berlin. However, the war in the Pacific, while running strongly against Japan, appeared likely to continue for a year or more. It had been a long and hard struggle. Following the sweeping and astounding successful Japanese offensive in late 1941 and early 1942, which saw them gain total control over the western half of the Pacific Ocean, the American victory at the Battle of Midway had begun to turn the tide. Through the following two years, in brutal fighting in the Solomon Islands, New Guinea, the Gilbert Islands, and the Mariana Islands, the Americans slowly pushed back the Japanese in a series of island-hopping campaigns. Meanwhile, the British struggled against the Japanese in Burma and the Chinese continued their own efforts to expel the Japanese from their territory.
In late 1944, the Americans landed in the Philippines and, in a series of bloody land and sea battles, took the islands back from the Japanese. It was at this point that the Japanese resistance reached the level of desperation, exemplified in the appearance of the kamikaze suicide attackers, who intentionally crashed their aircraft into Allied ships. In February of 1945, the Americans landed on Iwo Jima and, two months later, Okinawa. Both battles were characterized by fanatical Japanese resistance and heavy American casualties. Nearly 7,000 Americans died on Iwo Jima and more than 20,000 died on Okinawa. The closer the Americans approached the Japanese Home Islands, the fiercer the Japanese resistance seemed to become. At the same time, American B-29 bombers had begun to operate from airfields in the Mariana Islands, bringing death and destruction to Japanese cities on a previously unimaginable scale.
Before 1945, the battles in the Pacific War had been characterized by slowly increasing American experience in amphibious operations and a gradual refinement in Japanese defensive tactics. By the time Iwo Jima and Okinawa were invaded, the Allied operations were models of efficiency and effectiveness. For their part, the Japanese had given up the practice of defending the beach and instead allowing their enemies to consolidate on the shore and move inland before engaging them, thereby avoiding the worst of American naval bombardment. Both sides were planning on making the best use of their respective advantages in what was expected to be the largest amphibious invasion of all time.
It was going to be called Operation Downfall, a fitting name if ever there was one. It was envisioned as taking place in two phases. The first phase, code-named Operation Olympic, would be the invasion of Kyushu, the southernmost of the four main Japanese Home Islands. The intent was to capture the southern third of the island and to destroy the bulk of Japan's remaining military formations. The target date for the operation was November 1, 1945. Airfields would then be constructed on Kyushu to provide air cover for the second phase of Downfall, code-named Operation Coronet. It would be the decisive invasion of the main Japanese island of Honshu east of Tokyo, driving westward to secure the enemy capital. It was expected to be launched on March 1, 1946.
It would be an invasion on a scale that dwarfed even the Normandy campaign. The United States Sixth Army, which had been fighting the Japanese for years, was selected to lead Operation Olympic. It would consist of fifteen divisions, plus assorted attached units. with a total strength of more than 400,000 men. Backing them up would be the enormous naval forces of the Third, Fifth, and Seventh United States Fleets, which together deployed dozens of aircraft carriers and battleships, not to mention hundreds of cruisers and destroyers. The air power intended for the invasion was similarly massive, with tens of thousands of fighter and bomber aircraft being made ready.
Astonishingly, the forces being prepared for Operation Coronet were even larger. Two complete United States armies, the First and the Eighth, were to be involved. All told, thirty-one divisions would land on Honshu, more than twice as many as were going to land on Kyushu. The same immense naval and air power available for Operation Olympic would be available for Operation Coronet, much of it being based on the captured portion of Kyushu.
Not all of the invasion force was to be American. The British Pacific Fleet, one of the largest forces ever assembled by the Royal Navy, would place its battleships and aircraft carriers at the disposal of their American allies. A very large proportion of the aircraft involved would be provided by Australia. Moreover, a Commonwealth Corps consisting of British, Canadian, Australian and New Zealand troops would participate in Operation Coronet, although the participation of Indian units had been vetoed by the Americans. It was even proposed that French troops be involved, if only in symbolic numbers.
The Japanese had pieced together exactly what the Allied invasion plan was going to be, expecting an initial invasion of Kyushu followed by a final attack on Honshu. They decided to position most of their remaining forces for a do-or-die defense of Kyushu. Through the spring and summer of 1945, Japanese troops were moved onto Kyushu in enormous numbers. In mid-June, American intelligence estimated that around 350,000 Japanese troops were on Kyushu. In reality, the number was closer to 600,000.
On Iwo Jima and Okinawa, almost all Japanese soldiers had fought to the death rather than be captured, as had been the case in most previous island battles. There was no reason to think that the troops defending Kyushu would behave any differently. Orders issued in preparation for repelling the invasion specified that units were not to retreat, that no soldier was to stop fighting in order to care for a wounded comrade, and that any unarmed soldier should be prepared to take up the arms of a wounded or killed comrade. Indeed, one senior Japanese officer proposed killing all of the infirm and elderly people in Japan so as to free up food for the fighting forces.
Indeed, the Japanese were going to enormous lengths to ensure that the invasion would be as costly for the Allies as possible. Massive production of aircraft intended for kamikaze attacks was underway throughout 1945 and, by summer, around 10,000 were ready. During the fighting for Okinawa, around 2,000 kamikaze sorties had been mounted, which had sunk dozens of American ships, damaged many others, and killed thousands of men. The kamikaze attacks planned for the defense against the invasion of Kyushu would be five times more massive. Despite their best efforts, the Allies had been unable to provide an effective defense against kamikazes. At Okinawa, the Japanese had inflicted roughly 1.76 casualties per kamikaze sortie, but at Kyushu the attacks were likely to be more effective, for the approach would be of a much shorter distance and almost all of it overland, thus giving American air defenses much less time to respond. It seems reasonable to estimate that the casualty ratio would be as high as 2 per sortie, suggesting that the kamikazes would kill around 20,000 soldiers and sailors at sea during the landings. In addition, the Imperial Japanese Navy was preparing huge numbers of manned torpedoes, essentially underwater kamikazes, to attack American and Allies ships and landing craft.
Civilians were being mobilized in the defensive effort on an unprecedented scale. Women were trained to use weapons, from rifles to bamboo spears, and were expected to act as ammunition carriers during the fighting. Fishing and agricultural implements were fashioned into weapons and given to schoolchildren. Considering the behavior of Japanese civilians on Saipan and Okinawa, where many had preferred to commit suicide rather than turn themselves into the Americans, there was ever reason to believe that the coming invasion would be resisted by a civilian population ever bit as dangerous as the opposing army. American intelligence estimated that more than ten million civilians were being given rudimentary weapons training of some sort. If even one percent of them succeeded in causing an American casualty, one hundred thousand American soldiers would be killed or wounded.
Despite the lavish Japanese defensive preparations, there is no way the American invasion of Japan could possibly have failed. The Japanese were on the verge of starvation, under tight blockade, and so short of fuel that they were engaging in such desperate expedients as trying to liquefy plant roots into gas (which failed miserably). The Allies, by contrast, literally had the resources of the entire world to draw upon. Even the Japanese leadership recognized the hopelessness of their situation. Lacking the resources to repulse the invasion, the Japanese hoped only to cause such massive Allied casualties that some sort of negotiated settlement short of an outright surrender might be obtained. The odds of this happening were only slightly above zero, but it was the only hope the Japanese had on which to cling.
While ultimate success was guaranteed, there can be no doubt that any American invasion of Japan would suffer hideous casualties. Estimates of the number of killed or wounded were controversial even before the end of the war and have only become more so over time, especially in relation to the debate over the use of the atomic bombs on Hiroshima and Nagasaki. So how many casualties might have been sustained?
On Iwo Jima, the American invasion force of 110,000 had suffered roughly 7,000 men killed and 19,000 men wounded. This comes out to 6% of the force killed and 17% wounded, for total casualties of around 23%. On Okinawa, out of roughly 250,000 troops landed on the island, 20,000 were killed (8%) and 55,000 were wounded (22%), for total casualties of 75,000 or 30% of the invasion force. Assuming a similar ratio for Operation Olympic, we can assume about 30,000 dead and 80,000 wounded, for total casualties of 110,000. For Operation Coronet, an operation twice as large, we might assume casualties twice as heavy. Added together, we'd get 90,000 dead and 240,000 wounded, for a casualty total of 330,000.
This assumes, of course, that the invasion force would suffer casualties roughly equivalent to those suffered by the Americans on Iwo Jima and Okinawa. Considering the vastly more extensive defensive preparations made for the defense of the Japanese Home Islands, the expected participation of a huge and hostile civilian population, and the fact that the invasion of Japan would last much longer than the campaigns on Iwo Jima or Okinawa, I think it's safe to assume that rate of losses would be much higher. Well-informed observers, including Secretary of War Henry Stimson, estimated that American casualties might run close to a million men. Indeed, so many Purple Heart medals were ordered in anticipation of the expected casualties that the stockpile has never been used up; men wounded in Iraq and Afghanistan were presented with Purple Hearts that had been made in 1945.
What if the invasion of Japan had gone forward in 1945? We can be sure that it would have been an American victory and that, when the dust settled, the American flag would be fluttering over the ruins of Tokyo. We can be equally sure that it would have been the most nightmarish battle the world had ever seen. It's entirely possible that more Americans would have died in the invasion of Japan than had fallen in all the battles of the Second World War up to that time. Japanese casualties, military and civilian, would have been vastly larger than the total number who lost their lives in the bombings of Hiroshima and Nagasaki, with millions probably perishing. That being the case, we can only thank God that the invasion never had to take place.