Mao proclaims People's Republic of China

On 1 October 1949, Mao Zedong proclaimed the founding of the People's Republic of China with its capital as Beijing thus emerging as the victor from the Chinese Civil War which had been fought between the Nationalists and Communists since 1927.

General Chiang Kai-shek with some two million Nationalist soldiers retreated to the island of Taiwan from Sichuan province in December 1949. Although the Civil War had been interrupted by the Second Sino-Japanese war where both sides fought the Japanese from December 1936, the civil war resumed in December 1946.

Mao would single out the United States as the major threat to communist China's security. Historically, China would claim that its people had experienced a century of humiliation from the mid-19th century. Mao also perceived that American support for the Nationalists during the Civil War meant that the People's Republic of China would be the main target of the United States' crusade against Communism.

This led to the Chinese leadership pursuing a foreign policy that would seek to spread Communist revolution across those post-Second World War neighbouring states that, in the absence of colonial control, would emerge from Western Allied control. This would include Korea that had been part of the Japanese Empire and split into North and South Korea along the 38th Parallel. During the Civil War, the North Koreans had supported Mao's communist forces with both manpower and materiel during the fighting in the province of Manchuria as well as providing safe refuge for its non-combatants. It was this relationship that would later influence Mao's decision to commit the People's Army to drive back south from the Yalu River, the United Nation's Command, led by US General Douglas MacArthur.