Operation Coronet was intended to land on the Kanto Plain near Tokyo.
Coronet was the second stage of Operation Downfall, the proposed Allied invasion of Japan. Planners scheduled it for early 1946, after Operation Olympic had captured southern Kyushu and provided bases for further operations. Coronet would have attacked the Kanto Plain on Honshu, Japan’s largest and most populous main island.
The Kanto Plain contains Tokyo and surrounding areas, making it the political and industrial heart of Japan. The proposed landings would have used approaches including Sagami Bay and the Boso Peninsula. The plan called for a very large force, with American and Commonwealth units assigned to follow-on operations.
Coronet is often confused with Olympic because both were parts of Downfall. Olympic targeted Kyushu, while Coronet targeted the Tokyo region on Honshu. Japan’s surrender in August 1945 canceled both operations before either invasion began, so Coronet’s projected battle never became a historical campaign.