In the fourth century BC, Qin had become the most powerful state among existing seven states at the time. The Battle of Changping in 260 BC was a decisive victory and last major battle before Qin's uniting China.

Han, Wei, Yan, Zhao were all Qin's neibouring states. In 268 BC, Qin made Wei its subordinate and planned to make Han another. King of Han wanted to sever its Shangdan city to Qin in exchange for peace. But local official of Shangdang turned in the city to the state of Zhao, an ally state with Han. Qin then attacked Shangdang. Zhao army retreated to Changping. General Liang Po was appointed commander of Zhao army to fend off Qin invasion.

The Zhao army suffered some initial defeats in its offensive before Liang Po changed his tactics. He put up a defensive and waited the Qin army to get tired. The tactics took effect. Qin army was blocked at Changping and couldn't move any further. Lian Po waited for his chances for offensive.

However, the Qin army used the stratagem of sowing discord between Lian Po and the King of Zhao by spreading rumors that Lian Po was paving his way for surrender and the Qin army was only afraid of general Zhao Kuo, son of another famous general in Zhao.

Zhao Kuo had read a lot of military books but had never been in a battle personally. The arrogant and inexperienced young general changed Lian Po's strategy first thing he arrived Changping.

Meanwhile, Qin secretly replaced its commander with its best general Bai Qi. Bai Qi had his men pretended to be easily defeated and lured the Zhao army to pursue into its trap. Zhao Kuo attempted to break through the Qin encirclement but was shot dead by arrows. Headless Zhao army all surrendered.

With this victory, Qin had established military superiority over other states.