Battle of Changping
Lord Pingyuan is best known for his role in lifting the siege of Handan. After Zhao's catastrophic defeat by the state of Qin at the Battle of Changping, Qin continued to invade Zhao and besieged the Zhao capital Handan in 257 BC. Lord Pingyuan led a secret mission to the state of Chu, and secured the promise of King Kaolie of Chu to come to Zhao's aid, largely owing to the efforts of Lord Pingyuan's retainer Mao Sui.