Hanzhong Campaign

The Hanzhong Campaign was a military campaign launched by the warlord Liu Bei to seize control of Hanzhong Commandery from his rival, Cao Cao. The campaign took place between December 217 and August 219 during the prelude to the Three Kingdoms period. Although Cao Cao's forces had settled in Hanzhong Commandery two years prior after the Battle of Yangping, they were worn out by an overall Fabian strategy employed by Liu Bei's forces, who used targeted attacks to capture strategic locations from the enemy. One of these attacks resulted in the death of Xiahou Yuan, one of Cao Cao's top generals, delivering a huge blow to the morale of Cao Cao's forces. Due to logistical and other issues, Cao Cao was eventually forced to abandon Hanzhong Commandery and order a retreat in June 219. Liu Bei emerged victorious in the campaign and occupied Hanzhong Commandery, after which he declared himself "King of Hanzhong" in August of that year.

The campaign would ultimately prove to be the final military campaign that Cao Cao participated in before his death in March of 220. Provided by Wikipedia