emperor guangwu then turned his attention to chengjia. he commissioned his generals wu han, cen peng (岑彭), lai she (來歙), and gai yan (蓋延) to go on a two-pronged attack on chengjia—wu and cen leading an army and a navy up the yangtze river from modern hubei, while lai and gai led an army south from modern shaanxi. instead of fighting the eastern han expedition on the battlefield, gongsun tried to repel them by assassinating their generals—and he was initially successful, assassinating cen and lai and temporarily causing the eastern han forces to halt. however, eastern han forces regrouped, and in 36 they had gongsun surrounded in his capital chengdu (成都, modern chengdu, sichuan). however, initial attempts to siege the city was unsuccessful, and wu, then in command of the expeditory force, considered withdrawing. persuaded by his lieutenant zhang kan (張堪) that gongsun was in desperate straits, however, wu tricked gongsun into believing that the eastern han forces were collapsing from fatigue, drawing him out of the city and engaging in battle. gongsun was mortally wounded in battle, and chengdu surrendered in winter 36. liu's general wu han then killed more than 10,000 people.