One of the longest and largest civil wars of the 20th century — a struggle for control of China between the Nationalists (Kuomintang) and the Chinese Communist Party that ran, on and off, for more than two decades. It opened in 1927 with Chiang Kai-shek's bloody purge of the Communists, was partly suspended and overshadowed by the Japanese invasion, and resumed full-scale after 1945. It killed millions and ended in 1949 with Mao Zedong's Communist victory, the founding of the People's Republic on the mainland, and the flight of the Nationalist government to Taiwan — a division across the Taiwan Strait that remains unresolved.
In 1949, after more than twenty years of fighting, the mainland struggle in one of the longest civil wars of the modern age reached its decisive end. Two movements had spent a generation contesting who would rule China after the fall of its last empire: the Nationalists, who held the cities and a great army, and the Communists, who had once been hunted nearly to extinction. The Communists won. Mao Zedong proclaimed the People's Republic in Beijing, and the defeated Nationalist government fled across a hundred miles of water to the island of Taiwan, where it kept the name Republic of China and vowed to return. It never did. The war produced two governments, each claiming to be the true China, and split the Chinese world along a line that has not closed in three-quarters of a century.