Qin dynasty
Note: King Zhaoxiang of Qin (秦昭襄王) had already been ruling Qin for 51 years when Qin annihilated the Zhou dynasty; however the other six warring states were still independent regimes. Some Chinese historiographers thus used the next year (the 52nd year of King Zhaoxiang of Qin) as the official succession from the Zhou dynasty.
King Zhaoxiang of Qin
In 273 BC, Wei and Zhao allied together to attack Han's Huayang (華陽). Qin offered military help to Han, defeating and killing 130,000 Wei soldiers, and drowning 20,000 Zhao soldiers in the Yellow River. In 269 BC, King Huiwen of Zhao backflipped on his previous promise to send hostages and concede land. In response, Qin attacked Zhao and laid siege to Yuyu (閼與). The siege was lifted after the Zhao general Zhao She (趙奢) ambushed and decisively defeated the invading Qin army. In 265 BC, Qin struck back at Zhao and captured three cities, and King Huiwen of Zhao resorted to sending his son to the state of Qi in exchange for Qi assistance, which forced the Qin army to withdraw.