Battle of Ansi

Siege of Ansi
Part of the First campaign in the Goguryeo–Tang War

Map showing the invasion of Tang forces to Goguryeo
Date20 June – 18 September 645 CE
Location
Result Goguryeo victory
Belligerents
Goguryeo
Mohe
Tang
Commanders and leaders
In Ansi:
Yang Manchun
At Jupilsan:
Go yeon-su (POW)
Go hye-jin (POW)
Emperor Taizong of Tang
Li Shiji
Zhangsun Wuji
Li Daozong (WIA)
Xue Rengui
Strength
In Ansi: ~5,000 (garrison)
At Jupilsan: ~150,000 (reinforcements)
In Ansi: Unknown
At Jupilsan: ~30,000 soldiers
Casualties and losses
20,000+ killed
36,800 surrendered
2,000+ killed or injured
Korean name
Hangul
안시성 전투
Hanja
安市城 戰鬪
Revised RomanizationAnsiseong jeontu
McCune–ReischauerAnsisŏng chŏnt'u

The siege of Ansi took place between Goguryeo and Tang forces in Ansi, a fortress in the Liaodong Peninsula, and the culmination of the First campaign in the Goguryeo–Tang War. The confrontation lasted for about three months from 20 June 645 to 18 September 645.

The initial phase of combat resulted in the defeat of a Gorguryeo relief force of 150,000 and resulted in the Tang troops laying siege to the fortress. After a siege lasting around two months, the Tang forces constructed a rampart. However, the rampart was on the brink of completion, when a section of it collapsed and was taken over by the defenders which – along with the cold winter approaching as well as arriving Goguryeo reinforcements and the lack of supplies – forced Tang troops into a retreat. Over 20,000 Goguryeo troops were killed during the siege.