Honshu was the target of the planned Operation Coronet invasion.
Operation Coronet was the second phase of Operation Downfall, the proposed Allied invasion of Japan. It was planned as an assault on Honshu, Japan’s largest and most populous main island, after Operation Olympic had seized positions in southern Kyushu.
The proposed Coronet operation was scheduled for 1 March 1946. Its objective was to advance toward the Tokyo Plain and ultimately capture the political and industrial center of Japan. Operation Olympic, by contrast, was scheduled for November 1945 and targeted Kyushu.
Neither operation took place. Japan announced its surrender in August 1945 and formally signed the Instrument of Surrender on 2 September. The scale and projected cost of Downfall are often discussed in connection with the decision-making surrounding the final weeks of the Pacific War, although historians continue to debate how different factors influenced Japan’s surrender.