The Ten Victories and Ten Defeats, Steadying the Army
On the eve of Guandu, Cao Cao’s camp broadly doubted it could beat the far stronger Yuan Shao, and Guo Jia analyzed, point by point, how Cao Cao surpassed Yuan Shao in ten respects — magnanimity, strategy, martial skill, virtue, and more — clear and incisive, greatly heartening the army’s morale. This "ten victories and ten defeats" was no empty pep talk; the course of the war afterward all but bore out his every judgment.
A Posthumous Plan Settles Liaodong
On the return from the campaign against the Wuhuan, Guo Jia foresaw that the fleeing Yuan Shang and Yuan Xi would surely be killed by the local warlord Gongsun Kang in Liaodong, and advised Cao Cao not to pursue but to await good news — while he himself died of illness on the march home. Months later, Gongsun Kang indeed sent the heads of the Yuan brothers to sue for surrender, exactly as Guo Jia had predicted in life — this "posthumous plan" was his last gift to Cao Cao.