The hegemon king Xiang Yu of Western Chu made Zhang Er king of Changshan (常山王) during the Eighteen Kingdoms Period, but Zhang Er changed his loyalty to Liu Bang, the eventual founder of the Han dynasty and was titled as King of Zhao.
He married Liu Bang's daughter, Princess Yuan of Lu (posthumous title).
In 198 BC, his plot to kill Liu Bang was revealed, but he was pardoned and only demoted to Marquis of Xuanping (宣平侯).
He was succeeded as king of Zhao by the emperor's young son Liu Ruyi.
His posthumous title was Marquis Wu (武侯), but he was also venerated as King Yuan of Lu (魯元王).