Goguryeo–Tang War

Lore & Background

The Goguryeo–Tang War was fought between the Goguryeo kingdom and the Tang dynasty from 645 to 668, with both sides allying with various other states over the course of the conflict. The war began after Silla repeatedly requested Tang military assistance against Goguryeo, a request the Tang court began considering after decisively defeating the Göktürks in 628. The immediate pretext for the first Tang invasion in 645 was the murder of Goguryeo’s king by the military dictator Yŏn Kaesomun, who had seized power in 642 after killing over 180 aristocrats. Emperor Taizong of Tang launched a major campaign, commanding an armored cavalry force of 10,000 while General Li Shiji led an army of 60,000 Tang soldiers plus tribal forces, supported by a fleet of 500 ships carrying 40,000 conscripted soldiers and 3,000 elite volunteers. The Tang forces crossed the Liao River in May 645, captured the fortress of Gaimou after 11 days, and took 20,000 prisoners along with 100,000 shi of grain. They then defeated a Goguryeo relief army of 40,000 troops and burned the city of Liaodong with incendiary projectiles before breaching its walls. At the Battle of Jupilsan in July, a Tang force of 15,000 lured and flanked a Goguryeo army of 150,000, capturing 36,800 troops. However, the Tang could not take Ansi Fortress, defended by Yang Manch’un, despite attacking six or seven times daily and building a huge siege mound. Facing winter weather and dwindling supplies, Emperor Taizong withdrew on October 13, 645. Goguryeo successfully repulsed all Tang invasions from 645 to 648. After conquering Baekje in 660, Tang and Silla armies invaded Goguryeo from north and south in 661 but were forced to withdraw in 662. The war turned decisively after Yŏn Kaesomun died in 666, as Goguryeo became plagued by violent dissension, numerous defections, and widespread demoralization. The Tang–Silla alliance launched a fresh invasion in 667, aided by the defector Yŏn Namsaeng. In late 668, exhausted from military attacks and internal chaos, Goguryeo and the remnants of the Baekje army fell to the numerically superior Tang and Silla forces. The war ended the Three Kingdoms of Korea period, which had lasted since 57 BC, and triggered the subsequent Silla–Tang War over the spoils.

Reader's Guide

The Goguryeo–Tang War was a pivotal conflict that ended the Three Kingdoms of Korea period. The war demonstrated the military capabilities of both the Tang dynasty and the Korean kingdoms, with notable sieges such as that of Ansi Fortress, where the defenders repulsed repeated Tang assaults. The alliance between Tang and Silla proved decisive, but the war also sowed the seeds of the Silla–Tang War, as the two former allies fought over the conquered territories. The conflict highlighted the importance of internal stability: Goguryeo's collapse followed the death of its strongman Yŏn Kaesomun and the ensuing chaos. Overall, the war reshaped the political map of East Asia, leading to Silla's unification of most of the Korean Peninsula under its rule.

Did You Know?

• Goguryeo was one of the great powers in East Asia until its defeat by a Silla–Tang alliance in 668.
• The war ended after prolonged exhaustion and internal strife following the death of Yŏn Kaesomun.
• After its fall, Goguryeo's territory was divided between the Tang dynasty, Later Silla and Parhae.
• The name 'Korea' originates from 'Goryeo', a shortened form of Goguryeo adopted in the 5th century.
• Goguryeo was an active participant in the power struggle for control of the Korean peninsula and was associated with foreign affairs of neighboring polities in China and Japan.