Prince of Qin
In spring 620, Li Shiji served under Emperor Gaozu's son Li Shimin the Prince of Qin in resisting a major offensive by Liu Wuzhou the Dingyang Khan, and in an engagement against Liu's general Song Jin'gang (), Li Shiji was unsuccessful, but was saved by Li Shimin. (Li Shimin eventually defeated Liu, forcing Liu to flee to Eastern Tujue.)