What was the planned 1946 Allied invasion of the Tokyo region called?

The planned 1946 Allied invasion of the Tokyo region was called Operation Coronet.

Coronet was the second phase of Operation Downfall, the proposed Allied invasion of Japan. Planners scheduled it for 1 March 1946 and intended to land on the Kantō Plain, the broad region surrounding Tokyo. The operation would have followed Operation Olympic’s planned assault on Kyushu.

The Kantō Plain offered strategic access to Tokyo and major Japanese political and industrial centers. It was also expected to be heavily defended. Allied planners considered the operation so demanding that they assembled enormous numbers of troops, ships, aircraft, and supplies in preparation.

Coronet is often mixed up with Olympic because both were components of Downfall. Olympic concerned Kyushu, while Coronet concerned the Tokyo area. Japan’s surrender in August 1945 made both operations unnecessary, so Coronet remained a plan rather than a battle.