||This Three Kingdoms-related article describes a work or element of fiction in a primarily in-universe style. (October 2009)|
Serving Yuan Shao
The forces of Cao Cao and Yuan Shao clashed at the Battle of Guandu. Yuan dispatched Chunyu Qiong and others to guard the Wuchao granaries, where he kept his food supplies. Cao Cao personally led a raid on Wuchao with few men in disguise as Yuan's troops, as to debilitate Yuan. Zhang He, one of Yuan's generals, said to his lord: "Duke Cao's armies are elite, they would surely defeat Chunyu Qiong. After Chunyu Qiong is defeated, the army will scatter. Instead, let me and Gao Lan reinforce Wuchao." Guo remarked, "Zhang He's plans are bad. Instead, let us attack the original source (referring to Cao Cao's main camp), power will surely return to our side." "This explanation is why reinforcements should not be sent." Zhang He then replied: "Duke Cao's encampment is solidified, it is too hard to uproot. If Chunyu Qiong's camp is captured we will be depleted and captured in turn." "Cao will be too enveloped in taking Wuchao to leave a guard. I entreat you to attack his main camp."
Yuan Shao did not send the reinforcements to aid Chunyu Qiong, instead he sent five companies under Zhang He and Gao Lan to attack Cao's main army. Through a ruse involving Xu Chu and Zhang Liao, they beat out Chunyu Qiong and Yuan was led to believe that the granaries had been successfully defended. Yuan Shao's army was attacked on three sides, and when the men came back from Wuchao, they came up on Yuan's rear, surrounding the five companies. However, Zhang He and Gao Lan escaped, but altogether Yuan's army was defeated. When Chunyu reached the main army, which was devastated, he was brought in to see Yuan. Yuan railed at him asking why the defenses of the granary had been sparse. Chunyu's men told Yuan that Chunyu had been intoxicated that night, and Chunyu was executed forthwith. Guo was ashamed and plotted against Zhang He and Gao Lan, and said to Yuan, "Zhang He and Gao Lan were glad when your armies were defeated. "He was asked how he knew this and thus replied, "They have long wished to defect to Cao Cao, so when you put them on this duty, they did not try their best and brought on this disaster. Yuan then sent a messenger to recall and interrogate them, but Gao knew of the plans ahead of time and when the messenger came to recall them, he killed him and both Lan and Zhang truly defected to Cao, lest they be destroyed. They were warmly welcomed by Cao.
After Yuan Shao's death
After Yuan Shao died in 202, Guo became a staff advisor to Yuan's eldest son, Yuan Tan. During the impending attack on Ji Province, after the defeat at Guandu, Guo Tu was sent to muster Yuan Tan's troops. Further on, as the leader of the Yuan family was being decided after Yuan Shao's death, Guo Tu was sent to talk to Yuan Tan's younger brother Yuan Shang, whom Yuan Shao had destined for succession. Yuan Shang had two advisors that were very crafty in their dealings, and it was Guo's idea to separate the two men as to make it easier for Yuan Tan to win over Yuan Shang's title. When Guo reached Yuan Shang, Yuan Shang gave Yuan Tan the title of General and ordered him to attack Cao Cao. Guo asked, since no men of Yuan Tan were fit to give advice, if Yuan Shang could send his two advisors to help. Yuan Shang could only but send one, whom Guo accompanied back to Yuan Tan. Upon reaching Yuan Tan, the advisor grew suspicious and retired to his chambers. He then entrusted a message to be brought to Yuan Shang saying, "Guo Tu is very guilefull and is likely planning to harm you after Cao Cao is dealt with. Me being here is only to weaken your current situation. I advise letting Cao Cao do your work for you and withhold reinforcements." He did so, but Yuan Tan found out of the ruse and killed his brother's advisor. News of this reached Yuan Shang and he began to worry of his brother's defection, in which case Cao would approach his city without opposition, so he marched to help his brother at once. They arrived and immediately was stricken with many defeats against Cao Cao. So Yuan Tan and Shang went on the defensive and Cao withdrew momentarily. Again suspicion arose between Yuan Tan and Yuan Shang and Guo advised Yuan Tan set up a banquet for his brother's victory and assassinate him forthwith. The ruse was discovered by Yuan Shang, who brought five companies with him and besieged the city in which Yuan Tan resided. Guo, seeing defeat definite, advised surrendering to Cao, which Yuan Tan went about doing. Cao came with men and when he came upon the besieged city, Yuan Shang retreated back to Ji Province. Ji Province was besieged and Yuan Shang surrendered and was spared. Yuan Tan was to marry one of Cao's daughters and was sent to the capital, away from Guo.
- Chen Shou. Records of the Three Kingdoms (Sanguozhi).
- Fan Ye. Book of the Later Han (Houhanshu).
- Luo Guanzhong. Romance of the Three Kingdoms (Sanguo Yanyi).