Operation Downfall was a planned military action. This was to be the Allied forces invasion of Japan to end the Second World War. It would have two main parts, Operation Olympic would be the biggest amphibious invasion in history, in Kyūshū. Airplanes based in Kyushu would then be used for an even bigger invasion called Operation Coronet. This would invade Honshū. After the Atomic bombings of Hiroshima and Nagasaki, the Japanese surrendered, so there was no need for an invasion. Operation Downfall was canceled.