What was the codename for the first planned phase of Operation Downfall?

Operation Olympic was the first planned phase of Operation Downfall, aimed at invading Japan’s Kyushu island.

The proposed amphibious assault was scheduled for November 1, 1945. Allied planners expected Olympic to seize southern Kyushu and create bases for the later invasion of Honshu, Japan’s largest island.

The second phase, Operation Coronet, was planned for March 1946 and would have targeted the Tokyo Plain. Together, Olympic and Coronet formed the broader Downfall plan for defeating Japan through invasion if surrender did not occur.

Japan surrendered before Olympic began. The decision followed a combination of military and political developments, including the atomic bombings, the Soviet declaration of war, the rapid Soviet offensive in Manchuria, and the Japanese government’s acceptance of the Potsdam terms. Because the invasion was canceled, Olympic is best understood as a planned operation rather than a completed campaign.