structural:expansion
Battle of Guandu

After pacifying the nearby provinces, suppressing a rebellion by former Yellow Turbans, and consolidating power in the central government, Cao Cao turned his attention north to Yuan Shao, who had recently eliminated Gongsun Zan and now controlled most of northern China. Yuan Shao amassed a large army and camped along the northern bank of the Yellow River.

In the summer of 200, after months of preparations, Cao Cao and Yuan Shao clashed at the Battle of Guandu. Although Cao Cao was heavily outnumbered by Yuan Shao, he secured a decisive victory over his rival after launching a surprise raid on Yuan Shao's supply train and throwing the enemy into disarray. Yuan Shao retreated north after his defeat, fell ill and died about two years later. Cao Cao took advantage of Yuan Shao's death, which had resulted in internal conflict among his sons who were fighting over their father's territories, and advanced north to attack and seize all of Yuan Shao's lands. By the end of 207, after a victorious campaign beyond the frontier against the Wuhuan, Cao Cao achieved complete dominance of northern China. The territories in central and northern China which came under Cao Cao's control became the foundation of the state of Cao Wei, which would later be established by Cao Cao's son and successor Cao Pi.