Xiang Yu, the Hegemon-King of Western Chu, was hundreds of miles away in Shandong, campaigning against the rebellious State of Qi. His brutal tactics there -- burning homes, burying prisoners alive, capturing civilians -- had triggered more resistance than they suppressed. While Xiang Yu chased rebels across the Shandong peninsula, Liu Bang exploited the opening. Over the preceding months, Liu Bang had annexed the states of Henan, Haan, Western Wei, and Yin. He used Xiang Yu's assassination of the puppet Emperor Yi as a casus belli, donning white mourning robes and declaring a war of vengeance. A coalition converged on Pengcheng from three directions: a northern army crossing the Yellow River, a southern force marching from Yangxia, and Liu Bang's own central column accompanied by his advisors Zhang Liang and Chen Ping.

When Xiang Yu learned his capital had fallen, he left the bulk of his forces in Qi and personally led 30,000 crack cavalry south. Moving swiftly through the towns of Lu and Huling, they approached Pengcheng from the west and cut off the coalition army's route of retreat. At dawn, Xiang Yu struck. The coalition soldiers, unprepared and still disorganized from their celebrations, began to rout almost immediately. Through the course of the day, Xiang Yu's cavalry fought their way into the city itself, recapturing Pengcheng. The fleeing coalition troops had nowhere to go. According to the historian Sima Qian, more than 100,000 were slaughtered as they were driven into the Sishui and Gu Rivers east of the city.

The rout continued south. Survivors fled toward the hills, but Xiang Yu's cavalry pursued relentlessly, catching them at the Suishui River and driving them into the water. Sima Qian claimed another 100,000 died here, their bodies blocking the river's flow. Liu Bang escaped with a handful of mounted bodyguards. On the road he encountered his eldest daughter and second eldest son Liu Ying -- the future Emperor Hui. A famous and possibly fictional account describes Liu Bang, in his terror, dumping his own children from his chariot three times to lighten the load and move faster. Only the intervention of his coachman Xiahou Ying saved them. Less fortunate were Liu Bang's father and wife, who were captured by Chu forces and held as hostages.

Xiang Yu had achieved one of history's most lopsided military victories. With a force outnumbered perhaps eighteen to one, he had destroyed a coalition army and retaken his capital. But he returned to Pengcheng to restore order rather than pursuing Liu Bang to destruction. His general Han Xin -- not to be confused with Liu Bang's own brilliant strategist of the same name -- led a pursuit force westward, but Liu Bang's General-in-Chief Han Xin intercepted and defeated it in Henan. Liu Bang regrouped at the fortified city of Xingyang, established supply lines along the Yellow River, and settled into the grueling war of attrition that would eventually end at the Battle of Gaixia in 202 BC -- where Xiang Yu, surrounded at last, would take his own life. Pengcheng was the moment Xiang Yu should have won the war. Instead, it became the warning: even the most spectacular victory can be wasted.