On what date did the Japanese Instrument of Surrender become effective in 1945?

The Japanese Instrument of Surrender became effective on September 2, 1945.

Japanese and Allied representatives signed the document aboard USS Missouri in Tokyo Bay that morning. The ceremony began just after 9 a.m., and the instrument took effect at approximately 9:25 a.m. Japan Standard Time. This date is commonly identified as the formal end of World War II.

The date is sometimes confused with August 15, when Hirohito's recorded announcement was broadcast to the Japanese public. Japan had accepted the Allied terms before that announcement, and fighting largely stopped afterward, but the international legal and military ceremony came later. Different countries and traditions therefore use both dates when discussing V-J Day.

The document was signed by representatives of Japan and nine Allied governments: the United States, China, the United Kingdom, the Soviet Union, Australia, Canada, France, the Netherlands, and New Zealand. Its signatures transformed the earlier announcement into a formal capitulation.