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 (state)
In the middle of the 3rd century , Zheng Guo, a hydraulic engineer from the Han state, was sent to Qin to advise King Zhaoxiang of Qin on constructing irrigation canals. Qin had a penchant for building large-scale canals, as evident from its Min River irrigation system. King Zhaoxiang approved Zheng Guo's idea on constructing an even bigger canal. The project was completed in 264  and the canal was named after Zheng. Qin benefitted from the project as it became one of the most fertile states in China due to the good irrigation system, and also because it could now raise more troops as a consequence of increased agricultural yield.