King Zhaoxiang of Qin
In 293 BC, East Zhou decided to ally itself with the states of Han and Wei, and sent troops to help attacking Qin. However, the combined forces of this alliance was destroyed at Yique by the young Qin general Bai Qi, with 240,000 men killed and their commander Gongsun Xi (公孫喜) captured and executed. After this loss, the East Zhou was unable to actively participate in future interstate struggles in any significant fashion.
In 256 BC, Duke Wu of West Zhou (西周武公) allied with other states to stop the Qin offensive on the Han city of Yangcheng. In retaliation, King Zhaoxiang of Qin sent general Jiu to invade West Zhou, successfully breaking into Wangcheng. The Duke Wu was taken to Xianyang to beg for mercy, conceding all his lands. Both King Nan and Duke Wu would die later that year, and the subsequent Duke of West Zhou, Duke Wen (西周文公), was exiled to Danhuju (憚狐聚). Because the Zhou royal court had fallen from power and King Nan had died without a successor, the Eastern Zhou Dynasty collapsed, ending 879 years of Zhou monarchy. The remaining East Zhou state was also conquered by Qin chancellor Lü Buwei seven years later in 249 BC during the reign of King Zhaoxiang's grandson King Zhuangxiang, after Duke Jing of East Zhou attempted to form an anti-Qin alliance with other states.
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.