What was the name of the Allied ultimatum Japan accepted before its 1945 surrender?

The Allied ultimatum Japan accepted before its 1945 surrender was the Potsdam Declaration.

Issued on July 26, 1945, the declaration set out terms for Japan's surrender and warned of “prompt and utter destruction” if Japan refused. It was issued by the United States, the United Kingdom, and China during the Potsdam Conference in Germany.

The declaration called for the elimination of Japanese militarism, occupation of selected Japanese territory, disarmament of Japanese forces, and implementation of the earlier Cairo Declaration. It also stated that Japanese sovereignty would be limited to the home islands and other areas determined by the Allies.

Japan's government initially did not give an immediate acceptance. After the atomic bombings, the Soviet declaration of war, and intense internal debate, Emperor Hirohito directed the government to accept the declaration's terms. The surrender announcement followed in August, while the formal instrument was signed in September.