What was the planned second phase of Operation Downfall, aimed at Japan’s Kantō Plain near Tokyo?

Operation Coronet was the planned second phase of Operation Downfall, aimed at Japan’s Kantō Plain near Tokyo.

Coronet was scheduled for spring 1946 after Operation Olympic had captured southern Kyūshū and established bases for the next advance. The proposed landings would have targeted the Kantō Plain on Honshū, Japan’s largest main island. The area included Tokyo and was central to the planned defeat of the Japanese government and military.

Planning assigned major American armies to the operation, with additional British Commonwealth forces considered for reinforcement. Coronet was expected to be even larger than Olympic because it would have involved the main concentration of Allied ground forces against the Tokyo region.

The operation was never launched. Japan’s acceptance of the Allied surrender terms in August 1945 made both phases of Downfall unnecessary. Coronet is commonly mixed up with Olympic: Olympic meant the initial assault on Kyūshū, while Coronet meant the later attack near Tokyo. Both names belonged to the unrealized invasion plan.