Li Shiji
When Emperor Taizong and Li Shiji arrived at Ansi, it was said that the Ansi defenders, upon seeing the banner of the Tang emperor, began to yell insults from the walls. Emperor Taizong was insulted, and Li Shiji received permission to slaughter the city's male inhabitants when it fell—which led to the Ansi defenders fighting even harder. Li Shiji was unable to capture the city for some time. Go Yeonsu and Go Hyezin, who had by now accepted Tang titles, suggested: