The Chinese Civil War, spanning from 1927 to 1949, was a prolonged internal conflict within China. It pitted the Kuomintang (KMT)-led government of the Republic of China (ROC) against the forces of the Chinese Communist Party (CCP). Initially, from August 1927 to 1937, the KMT-CCP Alliance disintegrated during the Northern Expedition, allowing the Nationalists to assert control over most of China. However, between 1937 and 1945, hostilities paused as the Second United Front combated the Japanese invasion with assistance from the World War II Allies. After the defeat of Japan, the civil strife resumed, with the CCP gaining momentum in the decisive phase known as the Chinese Communist Revolution, lasting from 1945 to 1949. In 1949, the Communists seized power in mainland China, establishing the People's Republic of China (PRC) and compelling the leadership of the Republic of China to retreat to Taiwan. Since the 1950s, Taiwan and mainland China have remained in a political and military standoff, both claiming to be the legitimate government of all China. While tensions persist, overt conflict has largely ceased since the Second Taiwan Strait Crisis in 1979, although no formal peace agreement has been reached.