On what date did Japan first notify the Allies that it accepted the Potsdam Declaration?

Japan first notified the Allies that it accepted the Potsdam Declaration on August 10, 1945. The message included a condition that the declaration should not prejudice the emperor’s prerogatives.

The communication followed the atomic bombing of Hiroshima on August 6, the Soviet declaration of war on August 8, and the bombing of Nagasaki on August 9. Japan’s leaders were divided, but Emperor Hirohito supported ending the war. The government transmitted its acceptance through diplomatic channels.

This August 10 notification was not yet the final surrender ceremony. The Allies replied that the emperor would be subject to the authority of the Supreme Commander for the Allied Powers. Japan later accepted that response, and the emperor’s announcement was broadcast on August 15. The Instrument of Surrender was signed on September 2.