Chiang Kai-shek, leader of the Nationalist government of China, was detained by his subordinate generals Chang Hsüeh-liang (Zhang Xueliang) and Yang Hucheng, in order to force the ruling Chinese Nationalist Party (Kuomintang or KMT) to change its policies regarding the Empire of Japan and the Chinese Communist Party (CCP).Prior to the incident, Chiang Kai-shek followed a strategy of "first internal pacification, then external resistance" that entailed eliminating the CCP and appeasing Japan to allow time for the modernization of China and its military. After the incident, Chiang aligned with the Communists against the Japanese. However, by the time Chiang arrived in Xi'an on 4 December 1936, negotiations for a united front had been in the works for two years. The crisis ended after two weeks of negotiation, in which Chiang was eventually released and returned to Nanjing, accompanied by Zhang. Chiang agreed to end the ongoing civil war against the CCP and began actively preparing for the impending war with Japan.