What was the name of Japan’s military headquarters whose representative signed the 1945 surrender instrument?

Imperial General Headquarters was the Japanese military headquarters whose representative signed the 1945 surrender instrument.

General Yoshijiro Umezu, Chief of the Army General Staff, signed the document on behalf of Imperial General Headquarters. He signed shortly after Foreign Minister Mamoru Shigemitsu, who represented the Japanese government. The two signatures distinguished Japan’s civilian authority from the command structure directing its army and navy.

Imperial General Headquarters had been Japan’s highest wartime military command organization. It coordinated the Imperial Japanese Army and Imperial Japanese Navy, although the two services retained separate chains of command. Its authority extended across Japan’s large wartime empire and occupied territories.

The surrender ceremony therefore required more than a single Japanese signature. The instrument stated that Japan accepted the terms of the Potsdam Declaration and ordered all Japanese forces to cease hostilities. Umezu’s signature made the military command responsible for carrying out those orders, while Shigemitsu’s signature bound the government. Both signed aboard USS Missouri on 2 September 1945.