Chen Gong
In 198, Lü Bu launched an offensive against Liu Bei, who sought help from Cao Cao. This was one of Cao Cao's plots for he much desired the Xu Province. He placed two spies in Lü Bu's camp to sow discord between Lü Bu, Liu Bei and Chen Gong. These spies became the left and right advisers to Lü Bu and told him to attack Liu Bei. This was all against Chen Gong's advice. Cao Cao personally led his forces to attack Xiapi. When Cao Cao's army reached Pengcheng (彭城; present-day Xuzhou, Jiangsu), which was located east of Xiapi, Chen Gong advised Lü Bu to grasp the initiative to strike because he didn't know of Cao Cao's ploy but Lü Bu, heeding his wife's advice, decided to stay put. After initial attempts to break the siege failed, Lü Bu intended to surrender but was dissuaded by Chen Gong.