Sun Mingjiu joined the Northeast Army in 1927, and was sent to the Japanese Army NCO School in 1928. After returning home, he worked as an instructor under Zhang in Tianjin. Zhang is Zhang Xueliang's younger brother and Sun Mingjiu is Zhang's classmate. 193 1 year, Zhang Xueliang became the deputy commander-in-chief of the Kuomintang army, navy and air force, and went to Peiping from Nanjing via Tianjin. When passing through Tianjin, Zhang Xue Ming sent Sun Mingjiu to escort his brother Zhang Xueliang. Zhang Xueliang attached great importance to Sun Mingjiu and gave him a Swiss watch with a head on the surface.

Later, Sun Mingjiu successively served as Zhang Xueliang's confidential attendant and guard battalion commander, and became one of Zhang Xueliang's confidants. 1In July, 936, Zhang Xueliang established the secret political organization "Anti-Japanese Comrades Association" in order to establish the internal leadership core of the Northeast Army and realize its profound transformation. Zhang Xueliang is the chairman, and young officers headed by Sun Mingjiu and others are the main members. These young officers are young, energetic and radical, and they have long been dissatisfied with Chiang Kai-shek's policy of living at home and harassing foreign countries.

After Zhang Xueliang was detained by Chiang Kai-shek in Nanking, Sun Mingjiu and others advocated the use of force to save Zhang, and had a fierce conflict with Yu Xuezhong, a senior general of the Northeast Army who advocated a peaceful solution to the Guan incident. Finally, they sent someone to shoot Wang Yizhe, which led to the "February 22 incident", which made relatives suffer and the enemy quickly.

After the incident, the strategists of the Northeast Army were extremely angry and demanded that the murderer be severely punished. Zhou Enlai ordered Yingde Tian and Sun Mingjiu to be sent to the Red Army Soviet Area for temporary shelter. As a result, many military strategists angrily declared their loyalty to Nanjing and obeyed the orders of the central authorities. Others took the initiative to clear up * * *, and Gao Fuyuan, the first to help Zhang Xueliang contact China, was shot. At this point, the Northeast Army, as a group, collapsed and ceased to exist.

After Zhang Xueliang caught Chiang Kai-shek in the incident, Chiang Kai-shek said to Zhang Xueliang: Are you afraid that your subordinates will learn from you and play tricks with you in the future? Zhang didn't care at that time, but later Jiang's words came true. This time, it should not be aimed at Zhang Xueliang, but at the mastermind of the Northeast Army who stayed in Xi 'an after Zhang Xueliang went to Nanjing, and Sun Mingjiu and others laid hands on him.

Zhang Xueliang never dreamed that it was he who founded the Anti-Japanese Comrades' Association, a junior and middle-level officer he carefully trained, and finally sent the Northeast Army, which he tried his best to save and launched a mutiny, to the grave.