Guo Jia was always accurate in his judgments. In the beginning, Guo Jia joined and served Yuan Shao. Later he joined Cao Cao through Xun Yu's introduction. He assisted Cao Cao in the ruin of Lu Bu and the Yuan Shao family. Once Cao Cao said of him, "Only Fengxiao knows what is in my mind." As an advisor to Cao Cao he wielded great influence and Cao Cao had enormous faith in him. For example, when Liu Bei came seeking refuge, he persuaded Cao Cao to spare him or face rebellion by the people. He also convinced Cao Cao that he had nothing to fear in Yuan Shao. He said, "Consider these categories: duty, loyalty, politics, tolerance, strategy, moral virtue, charity, judgement, law and war. For Yuan Shao these are ten weak points that will lead to his defeat. You my Lord, excel in each of these areas, these are your ten points for victory."
     As he predicted, Cao Cao conquered Yuan Shao. Guo Jia also directed him in a way to bring down the rest of the Yuan clan. Since there was dissension in the family over the choice of a successor, he told Cao Cao that they would lead themselves into self-ruin.
     Guo Jia convinced Cao Cao to destroy them completely, "Though the prestige of our lord fills the empire, yet the people of the desert, relying upon their inaccessibility, will not be prepared against us. Wherefore I say attack, and we shall conquer them. Beside Yuan Shao was kind to the nomads, and the two brothers have been more so. They must be destroyed. As for Liu Biao he is a mere gossip, who needs not cause the least anxiety. And Liu Bei is unfit for any heavy responsibility and will take no trouble over a light one. You may leave the base with perfect safety and make as long an expedition as you choose. Nothing will happen."
     Guo Jia faithfully guided Cao Cao towards his goal, but died very early on in his career. Cao Cao deeply grieved and performed a grand sacrifice for his late adviser. Defeated in the Battle at Red Wall, Cao Cao cried in regret, "If only Guo Jia was alive, he would have averted me from this failure!"