By the end of the Warring States period, Zhao was the only state strong enough to oppose the mighty
Qin. An alliance with Wei against Qin began in 287 BC, but ended in defeat at Huayang in 273 BC. The struggle then culminated in the bloodiest battle of the entire period, the
Battle of Changping in 260 BC. Zhao's forces were utterly defeated by Qin. Although the forces of Wei and Chu saved Handan from a subsequent siege by the victorious Qin, Zhao would never recover from the enormous loss of troops in the battle. In 229 BC, invasions led by the Qin general
Wang Jian were resisted by
Li Mu and his subordinate officer Sima Shang () until 228 BC. Li Mu was one of the finest generals of the Warring States period, and although he was unable to defeat Wang Jian (also one of the best generals of the period), Wang Jian was unable to make any headway. The invasion ended in a stalemate. The Qin emperor,
Qin Shihuang, realised that he needed to get rid of Li Mu in order to conquer Zhao, and tried to sow discord among the Zhao leadership. The Zhao king
Youmiao fell for the plot: on the false advice of disloyal court officials and Qin infiltrators, he ordered Li Mu's
execution and relieved Sima Shang of his duties. Li Mu's replacement, Zhao Cong, was promptly defeated by Wang Jian. Qin captured King Youmiao and defeated Zhao in 228 BC. Prince Jia, half-brother of King Qian, was proclaimed
King Jia at
Dai and led the last Zhao forces against the Qin. This regime lasted until 222 BC, when the Qin army captured him and defeated his forces at Dai. During the rebellions at the end of the
Qin dynasty, a rebel named
Wu Chen, who had previously been serving
Chen Sheng and
Wu Guang of
Chu, proclaimed himself King of Zhao. Wu was later killed by his subordinate
Li Liang ().
Zhang Er and
Chen Yu (), former officials of Zhao, created the Zhao royal
Zhao Xie () as King of Zhao. In 206 BC, the rebel lord
Xiang Yu of Chu defeated the
Qin dynasty and made himself and seventeen other lords
kings. Zhao, in particular, was split into Dai (代) and Changshan (常山), with Zhao Xie as the King of Dai and Zhang Er as the King of Changshan. Chen Yu helped Zhao Xie reunify the land of Zhao by defeating Zhang Er, so Zhao Xie created Chen Yu as King of Dai. In 205 BC, Chen Yu's subordinate in Dai,
Xia Yue (), was defeated by
Liu Bang's generals
Han Xin and Zhang Er. Chen Yu was defeated by Han Xin in 204 BC, and later Zhao Xie was killed by Han forces. Liu Bang then made the state of Zhao a vassal state and gave its throne to Zhang Er, who had entered his service upon his defeat at the hands of Chen Yu. In 154 BC, an unrelated
Zhao, led by Prince of Zhao Liu Sui (), participated in the unsuccessful
Rebellion of the Seven States () against the newly installed sixth emperor of the
Han dynasty. ==Culture and society==