August 10, 1945

Surrender of Japan

Japan sends conditional acceptance of the Potsdam Declaration

Japan's first surrender message did not travel directly to Washington: neutral Switzerland carried it across enemy lines.

10 August 1945: the emperor breaks the deadlock

After Emperor Hirohito intervened to break a deadlock on 10 August 1945, an Imperial Conference decided that Japan would accept the Potsdam Declaration on the condition that the emperor's prerogatives as sovereign ruler be maintained.

Prime Minister Kantarō Suzuki had convened the divided leadership and asked the emperor to resolve the impasse. Foreign Minister Shigenori Tōgō then instructed Japan's representatives in Switzerland and Sweden to transmit the decision through those neutral governments.

Swiss chargé d'affaires Max Grässli delivered the formal message in Washington.

One sentence about the emperor

The message said Japan was ready to accept the Potsdam terms on the understanding that they contained no demand prejudicing the emperor's prerogatives as sovereign ruler. Japan did not ask to preserve all national sovereignty; the reservation was that specific.

It requested an explicit and rapid Allied assurance on that condition, which made it an opening in the surrender exchange rather than a final, unqualified acceptance.

The war did not end that day

On 11 August the four Allies replied that, from surrender onward, the authority of the emperor and the Japanese government would be subject to the Supreme Commander for the Allied Powers, and that Japan's ultimate form of government would be determined by its people's freely expressed will.

Japanese deliberations therefore continued. The public broadcast on 15 August and the formal signing on 2 September were separate later events.

Historians dispute the relative weight of Hiroshima, Nagasaki and Soviet entry in producing the 10 August decision; the sequence is clear, but calling any one blow the decisive cause goes beyond the evidence.

Sources

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What the sources leave uncertain

The August 10 date and diplomatic text are well documented.
Historians dispute the relative weight of Hiroshima, Nagasaki and Soviet entry in producing the decision. The sequence is clear, but describing any one blow as the sole or definitively decisive cause goes beyond the evidence.
The listed title paraphrases the condition as protecting the emperor's 'sovereignty.' The official English diplomatic text referred more precisely to his 'prerogatives' as a sovereign ruler.