Zhang Er (; c. 256 BCE – 202 BCE), courtesy name Junjia (君嘉), was a prominent Zhao aristocrat, insurgent leader during the Chu–Han Contention, and the first—and only—King of Changshan (常山王). A lifelong ally of Chen Yu and early supporter of Liu Bang, he helped coordinate anti-Qin uprisings in the final years of the Qin dynasty, governed northern Hebei under Xiang Yu's short-lived Eighteen Kingdoms scheme, and ultimately surrendered his realm to the founding emperor of the Han dynasty.
Early life.
Zhang Er was born in the Zhao heartland, likely near modern Handan, during the late Warring States period. Early chronicles in the "Records of the Grand Historian" describe him as a lesser aristocrat who forged a close friendship with Chen Yu, a fellow Zhao notable famed for his scholarship in military texts. When Zhao fell to Qin in 228 BCE, both men became low-level local officials under the Qin commandery system, quietly nurturing anti-Qin sentiment.
Rebellion against Qin.
In 209 BCE, the Dazexiang Uprising led by Chen Sheng and Wu Guang triggered widespread revolts. Zhang Er and Chen Yu organized Zhoujing (鉏井) insurgents, capturing the old Zhao capital of Julu. They proclaimed Zhao Xie—a remnant royal—as King of Zhao, with Zhang serving as Chancellor (丞相). Their forces later fought alongside Xiang Yu at the decisive Battle of Julu, helping shatter Qin's main northern armies.
Role in the Eighteen Kingdoms.
After Qin's collapse in 206 BCE, Xiang Yu partitioned the empire into the "Eighteen Kingdoms". Zhang Er was enfeoffed as King of Changshan, ruling six northern counties centered on present-day Shijiazhuang. Chen Yu became King of Dai, forming a Zhao–Dai alliance to buffer Xiang Yu's western flank.
Alliance with Liu Bang.
Xiang Yu's harsh reallocations alienated many regional rulers. In 205 BCE, when Liu Bang—then King of Han—advanced into the Central Plain, Zhang Er covertly pledged support. His son, Zhang Ao, married Liu Bang's eldest daughter, cementing the alliance. Changshan troops subsequently fought under Han Xin in the northern campaigns against Wei, Zhao, and Yan.
Abdication and death.
Following Liu Bang's final victory over Xiang Yu at Gaixia (202 BCE), the new emperor consolidated territory. Zhang Er submitted his royal seal and was created Marquis of Lu (盧侯). He died later the same year while accompanying the imperial court in Luoyang. The "Book of Han" records a posthumous title of King Wei (威王).