The Xi'an Incident of December 1936 , an important turning point in Chinese modern history, took place in the city of Xi'an during the Chinese Civil War between the ruling Kuomintang (KMT) and the insurgent Chinese Communist Party and just before the Second Sino-Japanese War. On 12 December 1936, Generalissimo Chiang Kai-shek, the leader of the Kuomintang, was arrested by Marshal Zhang Xueliang, a former warlord of Manchuria, and Commander of the North Eastern Army who had fought against the Japanese occupation of Manchuria and subsequent expansion into Inner Mongolia by the Japanese and troops of the puppet state of Manchukuo that had been created in Manchuria.