The Kantō Plain near Tokyo was the target of the planned 1946 Operation Coronet invasion.
Operation Coronet was the second stage of Operation Downfall, the Allied plan for invading Japan’s home islands. It was tentatively scheduled to begin on March 1, 1946, after Operation Olympic had seized part of southern Kyūshū. Coronet would have sent Allied forces onto the Kantō Plain on Honshū, Japan’s largest island.
The Kantō Plain was selected because it included Tokyo and offered a broad area for a major invasion and follow-up operations. The plan called for large forces to land on beaches near the Bōsō Peninsula and Sagami Bay before advancing toward the capital.
Japan surrendered before either Olympic or Coronet began. The two names are frequently mixed up: Olympic concerned Kyūshū, while Coronet concerned the Kantō Plain and the area around Tokyo.