What was the Allied ultimatum that Japan accepted before its formal surrender called?

The Allied ultimatum that Japan accepted before its formal surrender was called the Potsdam Declaration.

The declaration was issued on 26 July 1945 by the United States, the United Kingdom, and China during the Potsdam Conference. It called for the unconditional surrender of Japanese armed forces and warned that refusal would bring “prompt and utter destruction.”

Its terms required Japan’s military forces to disarm and return home, called for the removal of leaders associated with aggression, and promised that the Japanese people would not be enslaved or destroyed as a nation. It also stated that Japanese sovereignty would be limited to territories determined by the Allies.

Japan initially did not accept the declaration publicly. After the atomic bombings, the Soviet declaration of war, and intense internal debate, the Japanese government notified the Allies that it accepted the terms, subject to the emperor’s position. The 15 August broadcast and 2 September ceremony followed that decision.