The Chinese Civil War ( ), which lasted from April 1927 to May 1950, was a civil war in China between the Kuomintang (KMT or Chinese Nationalist Party) and the Chinese Communist Party (CCP). The war began in 1927, after the Northern Expedition, when the right-wing faction of the KMT, led by General Chiang Kai-shek, purged the Communists and KMT leftists from a KMT-CCP alliance. The war represented an ideological split between the Western-supported Nationalist KMT, and the Soviet-supported Communist CCP.

The civil war carried on intermittently until the looming Second Sino-Japanese War interrupted it, resulting in an organized and temporary Chinese resistance to the Japanese invasion. The Japanese assault and occupation was an opportunistic attack made possible by China's own state of internal turmoil. Japan's campaign was defeated in August, 1945 by the Allies, marking the end of WWII, and China's full-scale civil war resumed in 1946. Hostilities ended after 23 years in 1950, with an unofficial cessation of major hostilities, with the Communists controlling mainland China (including Hainan Island) and the Nationalists restricted to their remaining territories of Taiwan, Pescadores, and the several outlying Fujianese islands. To this day, no official armistice has ever been signed, although the two sides have close economic ties.