The first conflict of the Goguryeo–Tang War started when Emperor Taizong (r. 626–649) of the Tang dynasty led a military campaign against Goguryeo in 645 to protect Silla and punish Generalissimo Yeon Gaesomun for the killing of King Yeongnyu. The Tang forces were commanded by Emperor Taizong himself, and generals Li Shiji, Li Daozong, and Zhangsun Wuji.