Operation Olympic targeted Kyūshū in the canceled Allied plan to invade Japan in late 1945.
Operation Olympic was the first part of Operation Downfall, the proposed invasion of the Japanese home islands. It was scheduled to begin on November 1, 1945, and aimed to seize the southern portion of Kyūshū, Japan’s southernmost main island. Okinawa was intended to serve as a staging base for the assault.
A second phase, Operation Coronet, was planned for spring 1946. It would have invaded the Kantō Plain near Tokyo on Honshū. Japan’s surrender after the atomic bombings, the Soviet declaration of war, and the invasion of Manchuria canceled both operations before they began.
Operation Olympic would have involved a massive naval and air force effort, including dozens of aircraft carriers and battleships. Because the invasion never occurred, the planned code names are often discussed as counterfactual military history rather than as battles that actually took place.