In 626, Li Shimin, fearing that Li Jiancheng was about to kill him, ambushed Li Jiancheng and Li Yuanji at Xuanwu Gate and killed them. He then effectively forced Emperor Gaozu to first create him crown prince and then yield the throne to him (as Emperor Taizong). He reorganized his government, and as part of the reorganization, Xiao Yu and Feng Deyi were made co-heads of the important executive bureau (尚書省, "Shangshu Sheng"), with the title of "Shangshu Pushe" (尚書僕射). They soon came in conflict, however, as Feng would often agree with Xiao on important matters, and then change his recommendations once they were before Emperor Taizong. Xiao, later in 626, became sufficiently angry at Feng that he wrote a submission to Emperor Taizong, denouncing Feng using unartful language. Emperor Taizong, who was already displeased with Xiao, who was also conflicting with his other chancellors Fang Xuanling and Du Ruhui, soon removed Xiao from his post.