Qin's wars of unification
Qin's wars of unification (c. 230 - 221 BC) were a series of military campaigns launched in the late 3rd century BC by the state of Qin against the other six states remaining in China – Han, Zhao, Yan, Wei, Chu and Qi.
Source: Wikipedia — Qin's wars of unification (CC BY-SA 4.0)