The Zhou order had worked through the King sharing honor and authority with the feudal lords. As Qin adopted Legalist policies and relied on commoners, aristocrats were still in power across the rest of the Zhou world, overseeing reforms that were similar, but less radical. Their values were slow to change. Among other things, they tended to fight in such a way that they and their opponents could live to fight another day. As a Duke of Song, according to the Zuo Commentary, explained when refusing to attack enemy forces fording a river, “A gentleman does not inflict a second wound. He does not capture those with graying hair… I will not drum to attack when they have not drawn up ranks.” Defeated armies went home, and defeated states were not wiped out. The cohesion of the ruling class sharing authority was still strong. It took a second key advisor to change that, and invent the unified, centralized empire.
Fan Sui (d. 255 BC) came to Qin from the state of Qi to work as an advisor to the Qin rulers. It was he who energized them to follow through on their aim of uniting all the Zhou states. Fan insisted on direct royal rule, he attacked every attempt to parcel out new territory as fiefs instead of counties, he insisted on constant expansion, he developed professional troops to supplement the conscripts and replace all aristocratic soldiers, – and he demanded that Qin not only seize territory, but also kill people. No longer content to win battles, Qin slaughtered defeated soldiers. At the battle of Changping in 260 BC, for instance, Qin forces supposedly killed 400,000 Zhao soldiers. That may be an exaggeration, but the policy made conquest final. The Qin duke, now calling himself “king,” aimed at being the supreme ruler – the only man in all the states with a hereditary right to rule. Supreme rulership was built both on the productive and military labor of the common people, as organized by Shang Yang, and on their pitiless slaughter, instigated by Fan Sui.
The Qin war machine gobbled up one state after another, “as a silkworm devours a mulberry leaf,” in the words of Sima Qian. In 256 Qin, shockingly, took over the tiny remaining Zhou royal domain. King Zheng, the “tiger of Qin” led his forces to victory after victory, bringing down the state of Hann in 230 BC, Zhao in 228, and Wei in 225 BC. In 223, he defeated his most impressive rival, the southern state of Chu; the northern state of Yan fell in 222; and with the fall of Qi the next year, the new empire was complete. King Zheng credited his ancestors with his victory and began a grand ancestral cult to them. Qin had won the arms race by relying on iron and water, destroying the feudal system, creating meritocracy and bureaucracy, and registering every bit of data it could; and now it had created the empire.