The Treaty of San Francisco comes into effect, restoring Japanese sovereignty and ending its state of war with most of the Allies of World War II.

The Treaty of San Francisco , also called the Treaty of Peace with Japan , re-established peaceful relations between Japan and the Allied Powers on behalf of the United Nations by ending the legal state of war, military occupation and providing for redress for hostile actions up to and including World War II. It was signed by 49 nations on 8 September 1951, in San Francisco, United States, at the War Memorial Opera House. Italy and China were not invited, the latter due to disagreements on whether the Republic of China or the People's Republic of China represented the Chinese people. Korea was also not invited due to a similar disagreement on whether South Korea or North Korea represented the Korean people.

The Allies, formally referred to as the United Nations from 1942, were an international military coalition formed during World War II (1939–1945) to oppose the Axis powers. Its principal members were the "Big Four" – the United Kingdom, United States, Soviet Union, and China.