King Yeongnyu of Goguryeo, apprehensive about his general Yeon Gaesomun, is plotting with his other officials to kill him in the winter of 642.

When Yeon receives the news, he arranges a lavish banquet to celebrate his rise to the position of Eastern Governor to which one hundred of the opposing politicians of the kingdom are invited.

Yeon's soldiers ambush and kill all one hundred ministers present.

Yeon then proceeds to the palace and murders the king.

According to traditional Chinese and Korean sources, Yeon's men dismembered the dead king's corpse and discarded it without proper ceremony.

After placing a nephew of King Yeongnyu on the Goguryeo throne as King Bojang, Yeon appoints himself Dae Mangniji (Generalissimo).

Subsequently, in this role Yeon goes on to assume de facto control over Goguryeo affairs of state until his death around 666.

The ambitious Emperor Taizong of Tang leads an army of sixty thousand men across the Liao River into the northern Korean kingdom of Goguryeo in spring, 645.

Tang forces under Li Shiji heads southeast, toward the Yalu River, and put the strategic fortress city of Anshi under siege.

Taizong is unable to capture the fortress, which is defended by Yang Manchun.

Food supplies running low and winter coming on, he withdraws his forces, with the main Goguryan army still intact, and returns to China.

Taizong launches a second invasion of Goguryeo in 647 but, failing to subjugate the Korean kingdom, again withdraws.

China’s Tang dynasty faces increasing problems ruling the former inhabitants of Goguryeo, as well as Silla's resistance to Tang's remaining presence on the Korean Peninsula.

In 677, Tang crowns Bojang "King of Joseon" and puts him in charge of the Liaodong commander of the Protectorate General to Pacify the East.