The Chinese Civil War was a civil war in China fought between the Kuomintang (KMT)-led government of the Republic of China and the Communist Party of China (CPC) lasting intermittently between 1927 and 1949. Although particular attention is paid to the four years of fighting from 1945 to 1949, the war actually started in August 1927, after the KMT-CPC Alliance collapsed during the Northern Expedition. The conflict took place in two stages, the first between 1927 and 1937, and the second from 1946 to 1950; the Second Sino-Japanese War from 1937 to 1945 was an interlude in which the two sides were united against the forces of Japan. The Civil War resulted in a major revolution in China, with the Communists gaining control of mainland China and establishing the People's Republic of China (PRC) in 1949, forcing the Republic of China (ROC) to retreat to Taiwan. A lasting political and military standoff between the two sides of the Taiwan Strait ensued, with the ROC in Taiwan and the PRC in mainland China both officially claiming to be the legitimate government of all China.