On what date did Japan first notify the Allies that it intended to surrender in 1945?

Japan first notified the Allies that it intended to surrender on August 10, 1945.

The Japanese government sent the notification through diplomatic channels after Emperor Hirohito decided that the country should accept the Potsdam Declaration. Japan’s message included a condition concerning the Emperor’s position: the imperial institution could not be subject to the authority of another sovereign power.

The notification came after the atomic bombing of Hiroshima on August 6, the Soviet declaration of war and invasion of Japanese-held Manchuria on August 9, and the atomic bombing of Nagasaki on the same day. These events placed extraordinary pressure on Japan’s leaders and ended their hope that the Soviet Union might mediate a favorable peace.

Japan’s August 10 communication was an intention to surrender, not the final signed capitulation. The Allies replied through diplomatic channels, explaining that the Emperor would be subject to the Supreme Commander for the Allied Powers. Japan then made its public surrender announcement on August 15 in Japan.

The formal Instrument of Surrender was not signed until September 2 aboard USS Missouri. These separate stages are why the announcement date, notification date, and ceremony date should not be treated as identical.