What was the planned first phase of Operation Downfall against Japan?

Operation Olympic was the planned first phase of Operation Downfall against Japan.

Olympic called for an Allied invasion of southern Kyushu, the southernmost of Japan’s four main islands. The operation was tentatively scheduled to begin on November 1, 1945, at beaches near the island’s southern and eastern coasts. Its purpose was to establish bases and seize territory for the later assault on the main Japanese island of Honshu.

The second phase, Operation Coronet, was planned for March 1946 and would have targeted the Kanto Plain near Tokyo. Allied planners expected Olympic to require hundreds of thousands of personnel, as well as extensive naval and air support.

Japan surrendered before Olympic began. The operation was therefore canceled rather than defeated. Its existence helps explain why the 1945 surrender is studied alongside invasion planning: Allied leaders were preparing for a costly campaign while diplomatic and military pressure was pushing Japan toward capitulation.