In 193, Huang Zu led the forces of Liu Biao in a campaign against Sun Jian (Yuan Shu's subordinate general) and killed him. In 194, Sun Ce (aged 18) came into the military service under Yuan Shu. He was given the command of some troops who formerly had been commanded by his late father Sun Jian. In the south, he defeated the warlords of Yang Province, including Liu Yao, Wang Lang, and Yan Baihu. In 198, Sun Ce (aged 23) declared his independence from Yuan Shu who recently had declared himself emperor. He held control over Danyang, Wu, and Kuaiji commandaries (from present-day Nanjing to the Hangzhou Bay and some outposts at the Fujian coast), while expanding westward in a series of campaigns. By 200, he had conquered Yuzhang commandary (at present-day Lake Poyang in Jiangxi) and Lujiang (north of the Yangtze). In 200, Sun Ce was ambushed and assassinated by the former retainers of a defeated rival from Wu.