The Xi'an Incident of December 1936 (Xi'an Shibiuan) took place in the city of Xi'an during the Chinese Civil War between the ruling Kuomintang (KMT) and the rebel Chinese Communist Party and just before the Second Sino-Japanese War. On 12 December 1936, Generalissimo Chiang Kai-shek, the leader of the KMT was suddenly arrested and kidnapped by Marshal Zhang Xueliang, a former warlord of Manchuria, then Japan-occupied Manchukuo. The incident led the Nationalists and the Communists to make peace so that the two could form a united front against the increasing threat posed by Japan.