The planned Allied Operation Coronet invasion targeted the Kanto Plain near Tokyo.
Coronet was the second stage of Operation Downfall, the proposed invasion of Japan’s home islands. Allied planners expected it to follow Operation Olympic, which was aimed at southern Kyushu. Coronet was scheduled for early 1946 and would have struck the broad Kanto Plain on Honshu, the main Japanese island.
The Kanto Plain contains Tokyo and was strategically important because control of the region would have placed Allied forces at the center of Japan’s political and industrial life. Planning documents projected more than a million personnel for the operation, although exact force estimates changed over time. Japan’s surrender in August 1945 ended the need for the invasion, so Coronet was never launched. It is sometimes confused with Olympic because both belonged to Downfall.