Siege of Ansi
645 CE · Ansi Fortress (southeast of present-day Haicheng, Liaoning) · China · Early modern
The Tang army besieged Ansi Fortress for over two months without taking it and returned home when winter set in.
Belligerents
Tang
- Commanders
- Emperor Taizong of Tang, Li Ji, Li Daozong
- Strength
- Over 100,000 per records
Goguryeo
- Commanders
- Lord of Ansi Fortress (name not recorded), Go Yeonsu, Go Hyejin
- Strength
- A garrison of tens of thousands; the relief army is recorded as 150,000
Background
In 642 the powerful Goguryeo minister Yeon Gaesomun murdered King Yeongnyu, installed King Bojang, and allied with Baekje to attack Silla. Using this as a pretext, Emperor Taizong of Tang personally led a campaign against Goguryeo in 645.
Course of the battle
- Taking the Liaodong cities one after anotherLi Ji crossed the Liao River and took Gaimou; after Taizong arrived in person, Liaodong City fell and Baiyan surrendered.
- Battle of Mount ZhubiGo Yeonsu led a relief army to save Ansi; Taizong laid an ambush, attacked from several sides and crushed it, and Go Yeonsu and others surrendered.
- Building an earthen mound to storm the wallsThe Tang army built an earthen ramp day and night to close in on the walls; after more than 60 days, just as it was nearly finished, the ramp collapsed and was seized by the defenders instead.
- Returning home as winter sets inWith Liaodong's early cold, withered grass, frozen water and dwindling provisions, Taizong ordered the army home; crossing the Liao marshes, it ran into a snowstorm.
Outcome at a glance
| Date | 645 CE |
|---|---|
| Place | Ansi Fortress (around today's southeastern Haicheng, Liaoning) |
| Result | The Tang army besieged Ansi Fortress for over two months without taking it and returned home when winter set in. |
| Winner | Goguryeo (successful defense) |
| Casualties | At the Battle of Mount Zhubi the Goguryeo relief army suffered a crushing defeat, and Go Yeonsu and Go Hyejin surrendered with over 30,000 men; the Tang army also suffered losses in its siege assaults and retreat, but exact figures are unknown. |
| Territorial change | More than 70,000 inhabitants of the ten fortresses the Tang had taken, including Xuantu, Gaimou, Liaodong and Baiyan, were moved into the interior, but the road to Pyongyang remained closed. |
Impact
Ansi's stubborn defense sent Emperor Taizong of Tang's personal campaign home empty-handed. The Tang then switched to a strategy of harassment and attrition, and only after allying with Silla to destroy Baekje first did it conquer Goguryeo in 668.
See the world in 645 on the map →