In the summer of 1945, American leaders expected that a million American soldiers would soon be dead or injured.
Operation Chute – the code name for the planned amphibious invasion of Japan in 1945 – would have made the D-Day invasion of Normandy look like a piece of cake. The first phase – Operation Olympic, scheduled for November 1945 – involved the seizure of airfields on the southernmost Japanese island of Kyushu. These aerodromes would have provided aerial cover for Operation Crown, slated for March 1946, which landed Allied troops on the main island of Honshu, for an assault on Tokyo that would hopefully force Japan to surrender.
Eventually, Japan surrendered on August 15, after atomic weapons were dropped on Hiroshima and Nagasaki, and the Soviet Union declared war on Japan. But what if Japan hadn’t surrendered? What if the atomic bomb had not been invented, or if Japan had chosen to fight anyway, and the Allies had stormed Tokyo?
A computer wargame suggests that an invasion of Japan would have been a bloodbath.
Even in the summer of 1945, attacking Japan seemed a grim prospect. American soldiers had suffered from a forest during the bloody invasions of Iwo Jima and Okinawa, where Japanese troops fought to the death rather than surrender. How much more fanatic would have been their defense of the sacred Japanese homeland, including thousands of suicide bombers and planes that would have taken a heavy toll on Allied ships. Pentagon planners have warned Allied troops – mostly American, but backed by contingents from Britain, Canada, Australia and New Zealand – could suffer up to a million victims. Japanese military and civilian casualties would have been much heavier.
But on August 6, 1945, an American B-29 bomber dropped an atomic bomb on Hiroshima, followed by another atomic bomb on Nagasaki on August 9. Much to the relief of many Americans and Japanese, including my late father-in-law, a B-29 bomber that allegedly provided air support for Operation Olympic – Japan surrendered a few days later.
For decades, controversy surrounded the decision to drop The Bomb. The traditional story has been that atomic bombs prompted Japan to surrender and spared millions of Americans and Japanese. Revisionist historians argue that the atomic bomb was unnecessary and even immoral: Japan, already starved by the Allied naval and air blockade, would have surrendered anyway once the Soviet Union declared war on Japan. Or that the estimate of one million victims was exaggerated (for a good summary of the pros and cons, see This article by historian Alex Wellerstein).
Whichever argument is correct – or more likely both arguments are correct – historians have tended to focus on the high-level issues of war and peace, diplomacy, and weapons of mass destruction. . But what would a true Allied invasion of Japan have looked like?
A clue can be found in Japan ’45, by John Tiller Software, an amateur war game that describes Operation Olympic (a sequel, Japan ’46, covers the Coronet operation). Japan ’45 is a battalion-level simulation involving thousands of US Army and Navy, Japanese, British and French units maneuvering on a 2D map of Kyushu.
At first glance, the Allies appear to be an unstoppable juggernaut. They deploy an impressive number of units, including tanks, armored cars, infantry (foot and mechanized), paratroopers, commandos, artillery (towed and self-propelled) and anti-tank guns, supported by fighters, bombers, battleships and destroyers. They enjoy much greater firepower and mobility than the Japanese, whose army is mainly made up of foot infantry and World War I-style artillery.
But the unstoppable Allied war machine quickly came to a halt. To begin with, the terrain is not favorable for a mechanized army. In Japan ’45, Kyushu’s map is dotted with rice fields, forests, hills, villages, rivers and streams. Terrain limits movement to a front crawl and provides natural defensive cover for defenders. Despite all these allied Sherman tanks, there will be no dashing Patton-style blitzkriegs on Kyushu.
And what nature cannot provide, Japanese excavators will. Kyushu’s invading beaches are dotted with minefields, trenches, bunkers and pillboxes. The Allied player can only cringe as the bombs, napalm and one-ton shells from the battleships barely scratch the Japanese troops buried deep in their fortifications.
Finally, there is the Japanese soldier to face. The heart of the Imperial Army was its legendary resilient infantry, which could withstand the harshest hardships and preferred to fight melee with bayonets. While their weapons aren’t as good or plentiful as allied gear, they’re good enough to inflict massive casualties on invaders.
Playing Japan ’45, as the Allies against the AI-controlled Japanese side, graphically demonstrates that Operation Olympic would have been a meat grinder. The US Army and Navy assault troops that hit the shore suffered heavy losses from minefields, artillery, and machine guns. Pinned down on the exposed beaches, the skirmishers and engineers advance inch by inch. Eventually, the Japanese are dislodged from their entrenchments, and once in the open, they are vulnerable to the air and naval firepower of the Allies.
But then what? The terrain on Kyushu is too rugged and restricted to allow an Allied breakthrough. Once the Japanese defenders are driven out of the bushes, they simply regroup inland among the hills and woods, and the Allies must dig them up again.
The game suggests that the invasion of Japan might have looked like the Okinawa countryside, where US troops had to fight across multiple Japanese defensive lines in a battle of attrition that claimed 50,000 US casualties – and 400 ships sunk or damaged by suicide bombers – before Okinawa was conquered. As in Okinawa, the question is not whether the Allies will capture Kyushu, but what price they will pay for it.
That’s really what an invasion of Japan came down to. That Japan was invaded was proof that the war was lost. As an island nation, Japan’s first line of defense was the Imperial Navy and Air Force, and both rustle deep in the Pacific or in remote jungles.
Unless they capitulated, the best the Japanese could hope for was a divine miracle (and in fact, a massive typhoon in October 1945 would have severely disrupted Allied invasion plans). Or, to inflict so much loss as to bring the Allies to a negotiated peace. But after so many years of bloodshed, the allied nations were in no mood to negotiate anything other than Japanese surrender.
In the end, Japan gave up before the invasion was necessary. A fact for which many Americans and Japanese were right to be grateful.