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.
Lord Mengchang
In 299 BC, Lord Mengchang was sent to Qin on an official journey. King Zhaoxiang had heard so much about the young lord that he wanted to appoint him as the new Chancellor of Qin. However, King Zhaoxiang was warned by his ministers that Lord Mengchang was still loyal to his homeland of Qi, and soon put Lord Mengchang under house arrest. Desperate, Lord Mengchang sent a messenger to the king of Qin's beloved concubine for help. In exchange for her aid, the woman asked for the snow fox fur coat which Lord Mengchang had already given to the king as a gift when he first arrived in Qin. It was worth a thousand pieces of gold and there was not its like anywhere. King Zhaoxiang kept it in the royal treasury. One of Lord Mengchang's entourage in Qin was a skilled thief. He disguised himself as a dog and sneaked into the treasury under cover of darkness and retrieved the coat. Within two days, Lord Mengchang was released thanks to the pleas of the concubine. Lord Mengchang hired a chariot, forged his documents and dashed to the borders. By midnight of the next day, he had reached Hangu Pass—the last checkpoint of Qin before entering the territories of Qi. King Zhaoxiang had immediately regretted letting Lord Mengchang go and a small army was chasing him to bring him back. The guards at Hangu Pass would not let anyone pass through until the cock-crow at dawn. Lord Mengchang turned to his entourage for help. One of his aides could imitate all types of sounds. He crowed like a rooster, and this woke up the rest of the roosters. Not knowing that Lord Mengchang was being hunted, the guards at the pass then allowed Lord Mengchang and his entourage to enter Qi territory to safety.