In 194, while Cao Cao was away attacking Tao Qian in Xu Province, his subordinates Chen Gong and Zhang Miao rebelled against him and aided Lü Bu in taking over his base in Yan Province. Cao Cao abandoned his invasion of Xu Province and turned back to attack Lü Bu, culminating in the Battle of Yan Province which lasted more than 100 days. By 195, Cao Cao had retaken all his cities in Yan Province and defeated Lü Bu at Juye. Lü Bu and his men fled east to join Liu Bei, who had succeeded Tao Qian as Governor (州牧) of Xu Province.