Cao Hong
Between 217 and 219, Cao Zhen fought in Hanzhong Commandery against Cao Cao's rival Liu Bei, who had launched a campaign to seize control of Hanzhong Commandery from Cao Cao. When Liu Bei sent Wu Lan (吳蘭), one of his officers, to lead troops to garrison at Xiabian County (下辯縣; northwest of present-day Cheng County, Gansu), Cao Cao ordered his cousin Cao Hong to lead an army to attack the enemy. Along with Cao Xiu and Cao Hong, Cao Zhen fought at Xiabian County and defeated Wu Lan. He was promoted to Central Resolute General (中堅將軍) for his achievement.