On what date did the Allied occupation of Japan begin after the 1945 surrender announcement?

The Allied occupation of Japan began on August 28, 1945.

Occupation forces began entering Japan on August 28, several days before the formal surrender ceremony. General Douglas MacArthur served as Supreme Commander for the Allied Powers and directed the occupation. The first major landings included American forces arriving at Atsugi airfield and other locations.

The date is easy to confuse with August 15, when Emperor Hirohito's surrender announcement was broadcast, or September 2, when Japan signed the formal instrument. Those dates marked different stages of the surrender process. The occupation began in the interval between the announcement and the ceremony.

The occupation transformed Japan's political, legal, and economic institutions. It lasted until the Treaty of San Francisco came into force in 1952, although the United States retained administrative control over some territories for longer. MacArthur remained the central Allied authority during the main occupation period.