Zhangsun Wuji - During Emperor Gaozu's Reign

During Emperor Gaozu's Reign

Li Yuan captured Chang'an in winter 617 and declared Emperor Yang's grandson Yang You emperor (as Emperor Gong), taking power himself as regent. After he received news in spring 618 that Emperor Yang had been killed at Jiangdu (江都, in modern Yangzhou, Jiangsu) in a coup led by the general Yuwen Huaji, he had Emperor Gong yield the throne to him, establishing Tang Dynasty as its Emperor Gaozu. Li Shimin was created the Prince of Qin and thereafter became the main general in charge of his father's campaigns to reunify China under Tang rule, which was largely complete by 623, when the last major rival to Tang, Liu Heita the Prince of Handong, was captured and killed by Li Shimin's older brother, Li Jiancheng the Crown Prince. For Zhangsun Wuji's contributions to Li Shimin's campaigns, he was created the Duke of Shangdang.

By 623, however, Li Shimin was locked into an intense rivalry with Li Jiancheng, who was supported by another brother, Li Yuanji the Prince of Qi. For the next several years, the rivalry further intensified. By 626, Li Jiancheng and Li Yuanji, apprehensive that Li Shimin might act against them, had falsely accused Li Shimin's staff strategists Fang Xuanling and Du Ruhui and military officer Yuchi Jingde and had them removed from Li Shimin's staff. It was said that by that time, of Li Shimin's closest confidants, only Zhangsun remained, and that Zhangsun, his uncle Gao Shilian, Hou Junji, and Yuchi advocated acting first against Li Jiancheng and Li Yuanji. They persuaded Li Shimin to take action. Li Shimin thereafter set up an ambush for Li Jiancheng and Li Yuanji, killing them at Xuanwu Gate, and then effectively forced Emperor Gaozu to create him crown prince. Zhangsun was thereafter made the minister of civil service affairs. Two months later, Emperor Gaozu yielded the throne to Li Shimin, who took the throne as Emperor Taizong.