Emperor Gaozong of Tang
From 670 to 673 the rebels launched an uprising every year, the last of which lasted for four years. The Goguryeo loyalists were aided by the kingdom of Silla, who were angered by Emperor Gaozong of Tang. Originally Emperor Taizong of Tang promised to exchange Baekje and the lands south of Pyeonyang in return for Silla's military cooperation. However Taizong died before the conquest of Goguryeo was completed, and his successor Gaozong reneged on the promise.