Guo Jia told Cao Cao not to attack Gongsun Kang in a hurry. When Gongsun Kang and Yuan Erhu contend, the fisherman will benefit. Legacy refers to this matter.
At the end of the Eastern Han Dynasty, he went to Yuan Shao for the first time. But I don't think Yuan Shao can become a man. Later, he took refuge in Cao Cao and became a famous counselor under Cao Cao, offering wine to the official strategist. Note: The wine festival and the military adviser are already official positions, but Cao Cao specially set up a position called "wine festival for military advisers" for him. He made great contributions to Cao Cao's unification of northern China, which mainly happened when Cao Cao and Yuan Shao were fighting for power.