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.
The Qin Empire III
With the aid of the minister Fan Ju and general Bai Qi, King Zhaoxiang starts making aggressive advances against the other six states in the east. Under his rule, the Qin state destroys the Yiqu state, builds a section of the Great Wall, defeats the Qi and Chu states in battle, forces the Wei and Han states into submission, and inflicts a devastating defeat on the Zhao state at the Battle of Changping. After demonstrating its military power through its victories, in 256 BC the Qin state finally puts an end to the Eastern Zhou dynasty, the nominal suzerain power over the warring states. These events paved the way for the Qin state's eventual unification of China under the Qin dynasty within the next half-century.