Li Daozong
Meanwhile, Li Daozong was building a dirt mound to the southeast of the city to use as an attack mechanism, and in response, the Ansi defenders added to the height of the wall to the southeast. This process continued for 60 days, and eventually, the dirt mound got so high that from it, one could easily see inside the city. Li Daozong had his officer Fu Fu'ai () take position on the dirt mound. Suddenly, the mound had a partial collapse and fell onto the city walls, and the walls collapsed as well. At this moment, Fu, for reasons unexplained in history, left his position, and the Goguryeo forces took the opportunity to attack and capture the dirt mound, and instead used it as part of the defensive bulwarks. Emperor Taizong, in anger, executed Fu in public and ordered a heavy assault on the dirt mound, but could not capture it within three days. Li Daozong bared his feet and begged punishment, but Emperor Taizong pardoned him.