Cao Cao's unification of northern China was an important transitionary period in Chinese history. Occurring shortly after the fall of the Han Dynasty, it led to the establishment of the Kingdom of Wei, one of the major Chinese states during the Three Kingdoms period.

Cao Cao, a warlord who had been a prominent member of the previous Han Dynasty, had first established his power in northern China by defeating his rival, Yuan Shao, in the Battle of Guandu in 200 AD. This made Cao Cao the most powerful ruler in northern China.

A year after being defeated in battle, Yuan Shao died. Yuan Shao's eldest son, Yuan Tan, and his younger son, Yuan Shang , fought a protracted war over the succession, but neither was able to gain the upper hand. Eventually, Yuan Tan decided to give his allegiance to Cao Cao in exchange for help against his younger brother. With Cao Cao's backing, Yuan Shao's capital, the city of Ye, was captured. Yuan Shang fled, seeking the protection of Gongsun Zan, who had once been an ally of his father. Gongsun Zan, however, feared an attack from Cao Cao, and so killed both Yuan Shang and his other brother, Yuan Yao .

Yuan Tan, after having defeated his younger brother, attempted to rebel against Cao Cao's control. The attampt failed, however, and Yuan Tan was executed. Gongsun Zan later surrendered to Cao Cao. Thus, the reunification of the North was complete.

See also: Three Kingdoms