Zhang Xueliang
In 1919, Zhang Zuolin formed the Manchurian Army Military Academy 东三省陆军讲武堂, and Guo Songling was appointed as instructor in military tactics. One of his students was Zhang Zuolin's son Zhang Xueliang, who held Guo's capability in deep esteem. In 1920, Zhang Xueliang graduated from the Military Academy and was appointed a brigade commander in the Fengtian Army, and upon Zhang Xueliang's recommendation Guo was appointed to be the younger Zhang's chief of staff.