What was the official title of Douglas MacArthur’s Allied command during Japan’s 1945 surrender?

Douglas MacArthur’s official Allied command during Japan’s 1945 surrender was Supreme Commander for the Allied Powers.

The title is commonly abbreviated SCAP. MacArthur held it from the beginning of the Allied occupation of Japan in 1945 until 1951. At the surrender ceremony aboard USS Missouri, he signed the Instrument of Surrender in that capacity, representing the Allied powers as a whole.

SCAP was not simply a naval or field command. It gave MacArthur broad authority to supervise Japan’s occupation, demilitarization, political restructuring, and economic reforms under Allied direction. His headquarters operated in Tokyo, and the occupation formally began in late August 1945. The title is sometimes confused with MacArthur’s wartime positions in the Southwest Pacific Area, but SCAP specifically referred to the postwar Allied authority over Japan and its former imperial territories.