King Zhaoxiang of Qin
Reigning over 55 years, he was one of the longest-serving rulers during the Eastern Zhou Dynasty. Although making numerous policy mistakes during his later years, his aggressive territorial expansions were pivotal in consolidating the state of Qin as the dominant military powerhouse in the late Warring States period. It was the strategic dominance established during his reign that paved the way to Qin's eventual successful unification of China under his great-grandson, Ying Zheng.
Qin dynasty
The Qin were swift in their assault on the other states. They first attacked the Han, directly east, and took their capital city of Xinzheng in 230 BC. They then struck northward; the state of Zhao surrendered in 228 BC, and the northernmost state of Yan followed, falling in 226 BC. Next, Qin armies launched assaults to the east, and later the south as well; they took the Wei city of Daliang (now called Kaifeng) in 225 BC and forced the Chu to surrender by 223 BC. Lastly, they deposed the Zhou dynasty's remnants in Luoyang and conquered the Qi, taking the city of Linzi in 221 BC.