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.
Warring States period
In 265 King Zhaoxiang of Qin made the first move by attacking the weak state of Han which held the Yellow River gateway into Qin. He moved northeast across Wei territory to cut off the Han exclave of Shangdang north of Luoyang and south of Zhao. The Han king agreed to surrender Shangdang, but the local governor refused and presented it to King Xiaocheng of Zhao. Zhao sent out Lian Po who based his armies at Changping and Qin sent out general Wang He. Lian Po was too wise to risk a decisive battle with the Qin army and remained inside his fortifications. Qin could not break through and the armies were locked in stalemate for three years. The Zhao king decided that Lian Po was not aggressive enough and sent out Zhao Kuo who promised a decisive battle. At the same time Qin secretly replaced Wang He with the notoriously violent Bai Qi. When Zhao Kuo left his fortifications, Bai Qi used a Cannae maneuver, falling back in the center and surrounding the Zhao army from the sides. After being surrounded for 46 days, the starving Zhao troops surrendered in September 260 BC. It is said that Bai Qi had all the prisoners killed and that Zhao lost 400,000 men.