Which Allied plan for invading Japan was canceled after Japan surrendered?

Operation Downfall was the Allied plan for invading Japan that was canceled after Japan surrendered. It was a proposed two-stage invasion of the Japanese home islands, designed for the possibility that Japan would continue fighting.

Downfall consisted of Operation Olympic and Operation Coronet. Olympic was planned for southern Kyushu in late 1945, while Coronet was intended to attack the Kanto Plain near Tokyo in 1946. The plan required enormous forces, supplies, ships, and air support.

The invasion was never carried out because Japan accepted the Allied surrender terms after the atomic bombings of Hiroshima and Nagasaki and the Soviet declaration of war. The cancellation prevented a campaign that planners expected to involve severe casualties on both sides.

Operation Downfall is sometimes confused with Olympic, its first phase, or Coronet, its second phase. Downfall was the overall invasion plan; the other two names referred to its separate operations. Its existence also helps explain why Allied leaders were preparing for continued combat even as Japan's leadership debated surrender.