Cao Zhen
When Cao Zhen returned to Chang'an, Cao Cao appointed him as Commandant of the Central Army (中領軍). At the time, as his general Xiahou Yuan had been killed in action against Liu Bei's forces at the Battle of Mount Dingjun, Cao Cao was worried that Liu Bei would press on the attack at Yangping Pass (陽平關; in present-day Ningqiang County, Shaanxi). He commissioned Cao Zhen as Army Protector Who Attacks Shu (征蜀護軍) and ordered him and Xu Huang to lead troops to attack Gao Xiang, an officer under Liu Bei, at Yangping Pass. Cao Zhen and Xu Huang defeated Gao Xiang and drove him back. In 219, after a prolonged war against Liu Bei, Cao Cao eventually decided to give up defending Hanzhong Commandery so he withdrew all his forces. During the retreat, he sent Cao Zhen to Wudu Commandery (武都郡; around present-day Cheng County, Gansu) to meet up with Cao Hong and relay his order for them to retreat to Chencang (陳倉; east of present-day Baoji, Shaanxi).