ConflictJune – September 645(Lunar)
Siege of Ansi Fortress
Emperor Taizong of Tang took the Liaodong fortresses, but Ansi held out for 88 days and forced him to withdraw.
亜東印画協会 · Public domain · Source
Using Yeon Gaesomun’s coup as a pretext, Taizong invaded in 645 and took Gaemo, Liaodong and Baegam fortresses. A 150,000-strong relief army was beaten at Mount Jupil, but the defenders of Ansi even captured the earthen ramp the Tang army had piled against their walls. As winter came, Taizong retreated.
The commander of Ansi is unnamed in the official histories; the name Yang Man-chun first appears in Joseon-era writings.