The Allies celebrated victory over Japan on 15 August 1945, although the Japanese administration under General Koiso did not officially surrender with a signed document until 2 September. Both dates are known as VJ Day.
War with Japan had been brewing since the China incident in 1937, and the threat of war in the east intensified when Japan signed the Tripartite Pact with Germany in September 1940.
Japan's power in the Pacific was significant. By 26 November 1940 Cordell Hull presented Japan with a final statement of position following the Potsdam Conference: the US was not going to back down. Japan was outraged. On 7 December Japan transmitted a confusingly long statement to Washington, intended as a declaration of war. By the time it was formally presented, the US naval base at Pearl Harbor in Hawaii was under heavy attack from Japanese aircraft.
Japan enjoyed a series of early victories in Hong Kong, Burma and Malaya, the Philippines and Borneo. But this did not prevent austerity in Japan and the war effort greatly drained the economy. By 1943, defeat at Midway and Guadalcanal caused further hardship.
In 1944, massive increases in activities such as aircraft production meant a better war year for Japan. But as the Japanese braced themselves for an Allied invasion, the country came more or less to a standstill. On 9 March 1945, northern Tokyo came under US fire. Tens of thousands of civilians died and 40 square kilometres of the city were razed. Japan's poor defences were revealed.
And yet, still the Japanese refused to accept the terms of the Potsdam Declaration which demanded an unconditional surrender. The Japanese had asked Russia to act as intermediary for them at the Potsdam Conference, but Stalin was about to break the terms of the Russo-Japanese non-aggression pact (negotiated in 1941) and did not convey Japanese concerns. Without representation at Potsdam, Japan was doomed.
On 6 August 1945, the United States dropped the first ever atomic weapon on the Japanese city of Hiroshima. Japanese officials, despite the terrible consequences of the attack, convened to debate their next move.
The United States waited three days before dropping a second bomb on Nagasaki. The Japanese then began talks directly with the United States and, although their government's decision was not unilateral, Japan had little choice but to surrender. The Soviet declaration of war on Japan (on 8 August 1945) and the nuclear attacks on Nagasaki and Hiroshima forced Japan to face the facts, and the Empire disintegrated.
VJ Day marked not only the end of the war in the Pacific, but also the end of World War Two. In Britain, huge crowds gathered to cheer King George VI and his Queen en route to Westminster for the opening of Parliament.