What was the planned second phase of Operation Downfall against the Kanto Plain?

Operation Coronet was the planned second phase of Operation Downfall against the Kanto Plain.

Coronet was intended to begin in spring 1946 after Operation Olympic had secured southern Kyushu. Its target was the Kanto Plain on Honshu, the main Japanese island, including the area around Tokyo. The operation would have required a very large Allied force and extensive logistical preparations.

Planning assigned the U.S. First and Eighth Armies to the main assault, with additional Allied formations considered for later support. The proposed landings were expected to be larger than those of Operation Olympic because the Kanto region contained Japan’s capital and major population centers.

Coronet was never executed. Japan surrendered in August 1945, before the scheduled invasion. The name is sometimes confused with Olympic, which was the earlier Kyushu operation, or with Downfall, the umbrella plan covering both phases.