How did the communist party gain its power??

The Sino-Japanese War of 1937–1945 (part of World War II) forced an uneasy alliance between the Nationalists and the Communists. With the surrender of Japan in 1945, China emerged victorious but financially drained. The continued distrust between the Nationalists and the Communists led to the resumption of the Chinese Civil War. In 1947, constitutional rule was established, but because of the ongoing Civil War many provisions of the ROC constitution were never implemented on the mainland. After its victory in the Chinese Civil War, the Communist Party of China (CCP) led by Mao Zedonggained control of most of Mainland China.