What it was
The party was founded at its First Congress in Shanghai in July 1921 — concluding, by tradition, on a boat on South Lake at Jiaxing — with about 13 delegates, among them Mao Zedong. It grew out of the New Culture and May Fourth ferment, with Chen Duxiu and Li Dazhao as its intellectual founders.
Role
A First United Front with the Kuomintang (1924–27) ended in the purges of 1927. The party then built rural soviets and the Red Army, survived the Long March (1934–36), and consolidated in the Yan’an years; a second united front against Japan followed in 1937–45. Victory in the civil war brought the founding of the People’s Republic in 1949.
Fate
In power, the party carried out socialist transformation, then led the Great Leap Forward and the Cultural Revolution under Mao — judged in the party’s own 1981 Resolution to contain grave errors — followed by the reform era from 1978 under Deng Xiaoping and his successors. It is the PRC’s constitutionally leading party.