Jia Xu
When Cao Cao was appointed as the Governor of Ji Province after pacifying northern China, Jia Xu was reassigned to be a Palace Counsellor (太中大夫) instead. In 208, after Cao Cao had annexed Jing Province, he planned to press on and attack the territories in Jiangdong controlled by the warlord Sun Quan. Jia Xu advised him against it and said: "My lord, you have defeated the Yuans and now you have taken Jing Province. Your name spreads throughout the Empire and your military is very strong. If you follow in the footsteps of the Chu state by attracting talents to serve in the government and by improving the lives of the people, you won't need to resort to force to subdue the Jiangdong territories. They will be submit to you on their own." Cao Cao ignored Jia Xu and proceeded to attack Jiangdong. He lost the decisive Battle of Red Cliffs against the allied forces of Sun Quan and Liu Bei later that year.