In 202, when the warlord Cao Cao led his forces to attack Yuan Shang and his brother Yuan Tan at the Battle of Liyang, Yuan Shang ordered Gao Gan, Guo Yuan and Huchuquan to lead troops to attack Hedong Commandery (河東郡; around present-day Xia County, Shanxi), which was guarded by Jia Kui, an official under Cao Cao.
Ma Teng, a warlord in Liang Province, responded to Zhong Yao's call and sent his son Ma Chao and an officer Pang De to assist Zhong Yao in attacking Guo Yuan and Gao Gan at Pingyang County (平陽縣; west of present-day Linfen, Shanxi).
After the battle, when Zhong Yao's men searched the battlefield, they found Guo Yuan's headless body.
Shortly after, Pang De went to meet Zhong Yao and he threw Guo Yuan's head in front of him.
Pang De immediately apologised to Zhong Yao, who replied, "Even though Guo Yuan was my nephew, he was an enemy of the state.