The Xuanwu Gate Incident was a palace coup for the throne of the Tang dynasty on 2 July 626, when Prince Li Shimin (Prince of Qin) and his followers assassinated Crown Prince Li Jiancheng and Prince Li Yuanji (Prince of Qi). Li Shimin, the second son of Emperor Gaozu, was in an intense rivalry with his elder brother Li Jiancheng and younger brother Li Yuanji. He took control and set up an ambush at Xuanwu Gate, the northern gate leading to the Palace City of the imperial capital Chang'an. There, Li Jiancheng and Li Yuanji were murdered by Li Shimin and his men. Within three days after the coup, Li Shimin was installed as the crown prince. Emperor Gaozu abdicated another sixty days later and passed the throne to Li Shimin, who would become known as Emperor Taizong.