贾诩
In 199, when Cao Cao and Yuan Shao were about to clash at the Battle of Guandu, Yuan Shao sent a messenger to meet Zhang Xiu and propose an alliance between them against Cao Cao. Zhang Xiu wanted to agree, but Jia Xu, who was beside him, said to Yuan Shao's messenger: "I say 'No, thank you.' to Yuan Benchu. He can't even accommodate his own brother. What makes him think he can accommodate talents from around the Empire?" A shocked Zhang Xiu turned to Jia Xu and asked: "Why do you have to say this? What will become of me now?" Jia Xu replied: "Why don't you submit to Cao Cao?" Zhang Xiu asked: "Yuan Shao is powerful while Cao Cao is weak. Besides, I am also Cao Cao's enemy. What will happen if I submit to him?" Jia Xu replied: "That's why it is better for you to submit to Cao Cao. He controls the Empire in the name of the Emperor. This is the first reason why you should submit to him. Yuan Shao is militarily more powerful. You have less troops than him, so even if you join him, he won't regard you highly. Cao Cao has less troops. If you join him, he'll be delighted. This is the second reason why you should submit to him. A man who aspires to become a great ruler will be more willing to put aside personal enmities and make his virtues known to people. This is the third reason why you should submit to Cao Cao. I hope you won't have any more doubts." Zhang Xiu heeded Jia Xu's advice and led his forces to surrender to and join Cao Cao.