King Munmu Launches Campaign Against Goguryeo

In 667 CE, King Munmu of Silla initiated a coordinated military campaign with the Tang Dynasty aimed at defeating the Goguryeo kingdom, setting in motion events that led to its fall in 668 CE. This campaign was part of Silla’s broader strategy to unify the Korean Peninsula during the final phase of the Three Kingdoms period. The campaign followed a critical shift within Goguryeo after the death of its powerful leader Yeon Gaesomun in 666. His death triggered internal conflict among his sons, weakening the state’s ability to defend itself. Yeon Namsaeng, the eldest son, defected to the Tang Dynasty, while his brother Yeon Jeong-to aligned with Silla. These defections provided the Silla–Tang alliance with strategic intelligence and internal support, undermining Goguryeo from within. In early 667, Tang forces under General Li Shiji advanced from the north, while Silla forces coordinated attacks from the south under King Munmu’s leadership. This two-front offensive placed significant pressure on Goguryeo’s defenses and limited its ability to respond effectively. The combined forces gradually penetrated deeper into Goguryeo territory over the course of the campaign. By 668, the allied forces reached the capital, Pyongyang. After a prolonged siege, the city fell on 22/10/668, bringing an end to Goguryeo, a kingdom that had existed for several centuries. The fall of Pyongyang marked a decisive shift in the balance of power on the Korean Peninsula and concluded one of the major conflicts of the Three Kingdoms era. The campaign of 667–668 paved the way for Silla’s dominance, although it also led to later tensions with the Tang Dynasty over control of the peninsula.