FYI
Operation Olympic and Operation Coronet were the two phases of Operation Downfall, the planned Allied invasion of Japan during World War II. These operations were developed in 1945 to force Japan’s surrender if the atomic bombs and diplomatic efforts did not lead to Japan’s unconditional surrender. Here’s a breakdown of both operations:
Operation Olympic
• Objective: To invade the southern island of Kyushu, the third-largest and southernmost of Japan’s four main islands.
• Timeline: Scheduled for November 1, 1945.
• Forces: Involved a massive amphibious assault, with U.S. troops landing at multiple points along Kyushu’s southern coast.
• Strategic Goal: To secure airbases and establish a foothold for a larger invasion of Japan’s main island, Honshu, which would come in the second phase (Operation Coronet).
• Resistance: U.S. planners anticipated fierce resistance. The Japanese military had anticipated an invasion of Kyushu and heavily fortified the island, with hundreds of thousands of soldiers prepared to defend it.
• Casualty Estimates: Some military officials estimated that U.S. casualties could be between 250,000 and 500,000 in the invasion of Kyushu alone. Japanese civilian and military casualties were expected to be much higher.
Operation Coronet
• Objective: To launch a massive assault on Honshu, Japan’s largest and most populous island, particularly targeting the Tokyo Plain.
• Timeline: Planned for March 1946, after securing Kyushu in Operation Olympic.
• Forces: This would have been an even larger invasion than Operation Olympic, involving over 40 divisions from the U.S. and Allied forces, potentially the largest amphibious operation of the war.
• Strategic Goal: The capture of Tokyo and the heart of Japan, forcing the Japanese government to surrender.
• Resistance: Even greater resistance was expected in Honshu, with Japanese forces, both military and civilian, preparing for an all-out defense of their homeland.
• Casualty Estimates: Estimates varied, but some predicted upwards of 1 million Allied casualties and potentially millions of Japanese military and civilian deaths due to the expected ferocity of the fighting and the possibility of mass suicides among civilians.
Why the Plans Were Not Executed
The dropping of the atomic bombs on Hiroshima and Nagasaki, along with the Soviet Union’s declaration of war on Japan, pushed Japan to surrender in August 1945, before Operation Downfall could be put into motion. The potential cost in human lives—both Japanese and Allied—was one of the reasons why the atomic bombs were seen as a necessary evil by many military planners and political leaders at the time.