Belligerents
Background
For the new master of Yi Province, Hanzhong was a knife at the throat — as long as Cao Cao held it, Shu lay open to invasion. Fa Zheng pressed the case: Xiahou Yuan and Zhang He were beatable. In 217, Liu Bei committed for the first time to a full war against Cao Cao himself.
Course
After nearly two years of grinding, Liu Bei shifted onto Mount Dingjun in 219, looking down on the Wei lines. The instant Xiahou Yuan split his force to repair a palisade, Fa Zheng gave the signal — and Huang Zhong came down the mountain with the drums, cutting Xiahou Yuan down. When Cao Cao arrived with the main army, Liu Bei sat tight on the high ground and refused battle, while Zhao Yun’s open-gates bravado at the Han River threw back the pursuit. His supply lines withering, Cao Cao withdrew — leaving behind the watchword "chicken ribs."
Outcome & impact
Liu Bei’s first and greatest head-to-head victory over Cao Cao; that year he took the title King of Hanzhong. Shu gained its northern rampart, the launching pad of every later campaign. But the same year Jing Province fell, and the triumph was short-lived.
History vs. the novelHistoryvsNovel
The novel inflates the Huang Zhong–Yan Yan double act and Zhao Yun’s heroics, but the beheading at Dingjun and the empty-camp ruse at the Han River are in the record. The histories are clearer about the campaign’s hidden author, Fa Zheng — even Cao Cao reportedly said Liu Bei could never have devised it himself.