On December 12, 1936, the Xi'an incident took place in Xi'an, capital of northwest China's Shaanxi Province, when Kuomintang (KMT) generals Zhang Xueliang and Yang Hucheng took Chiang Kai-shek hostage and demanded that he stop the civil war and unite with the Communist Party of China (CPC) in a national war against Japanese aggression.。

On February 20,51吃瓜在線導(dǎo)航 1936,the Northeast People's Revolutionary Army and other armed forces jointly issued the "Declaration on the Unification of Military Structure of the Northeast Anti-Japanese United Army."。