Zhangsun Wuji
It was said that Zhangsun Wuji was studious, and that he was both intelligent and full of strategies. When his sister later married Li Shimin, the second son of the general Li Yuan, he and Li Shimin became great friends. When Li Yuan, at Li Shimin's instigation, rose against the rule of Emperor Yang of Sui in 617 and attacked the capital Chang'an, Zhangsun Wuji went to meet Li Shimin, then serving as a major general of his father's, and he began to serve on Li Shimin's staff, often following Li Shimin on various campaigns.