Key Facts
- Duration
- ~3 months (20 Jun – 18 Sep 645)
- Goguryeo relief force defeated
- 150,000 troops routed
- Goguryeo casualties
- over 20,000 killed
- Result
- Tang forces retreated after failed siege
Strategic Narrative Overview
Tang forces advanced into the Liaodong Peninsula and initially defeated a Goguryeo relief army of 150,000 troops, then laid siege to the fortress of Ansi. Over approximately two months, Tang troops constructed a large earthen rampart intended to overlook and overwhelm the fortress walls. However, a critical section of the rampart collapsed near completion, and Goguryeo defenders quickly seized control of it, frustrating the Tang assault.
01 / The Origins
The siege of Ansi was the culminating engagement of the Tang dynasty's first military campaign against Goguryeo, a Korean kingdom controlling Manchuria and the northern peninsula. Emperor Taizong launched the campaign in 645, seeking to subdue Goguryeo and reassert Chinese dominance over the Liaodong region, exploiting internal instability within Goguryeo following a coup by the military strongman Yeon Gaesomun.
03 / The Outcome
With the rampart lost to the defenders, winter approaching, Goguryeo reinforcements arriving, and supplies running low, Tang Emperor Taizong ordered a withdrawal. The siege ended on 18 September 645 as a Goguryeo defensive success. Tang forces retreated without capturing Ansi, concluding the first campaign of the Goguryeo–Tang War and leaving the broader conflict unresolved.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Side B
1 belligerent
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.