Emperor Taizong of Tang
In 645, the Emperor Taizong of Tang led a major expedition against Goguryeo by land and sea, but Yeon Gaesomun and Yang Manchun repelled the invasion, as well as subsequent smaller attacks by the Tang. In 654, Goguryeo attacked the Khitans, who were allied with the Tang. In 655, Goguryeo and Baekje attacked Silla.