Battle of Guandu
From 196 onwards it became increasingly clear that there would be a confrontation between the two warlords Yuan Shao and Cao Cao for dominion of the north sooner or later. In such an eventuality, the position of Guandu would become of strategic importance. It was close to the Yan Ford on the Yellow River and lay directly on the route to Xuchang. Cao Cao was the first to recognise its importance and in the autumn of 199, he moved forces there and prepared fortifications. The next year, Liu Bei defected from Cao to his rival Yuan Shao. Yuan took the opportunity to mount a campaign in the south and in the first month of 200, his vanguard attacked the garrison of Liyang, just north of the Yellow River. The commander at Liyang, Yu Jin, signalled to headquarters the approach of Yuan Shao. Cao Cao immediately regrouped his troops and stationed 20,000 men at Guandu in preparation for a decisive battle in the new future.
Above map courtesy of Rtkweb.com
Soon Yuan Shao's main army arrived, boosting his numbers to 110,000, including 10,000 cavalry. His general Yan Liang crossed the Yellow River and attacked the city of Baima. Under the advise of Xun Yu, Cao Cao led a battalion across the Yan Ford on the Yellow River. But this manoevre proved to be only a feint, and as soon as Yuan Shao drew troops from Baima to counter Cao's attack, Cao Cao retreated and struck east to relieve Baima. In the ensuring battle, General Yan Liang was killed and the Yuan troops disastrously routed. After this Cao Cao prepared to abandon the city and evacuated the residents south. Taking advantage of the situation, Wen Chou and Liu Bei, leading 6000 light cavalry, were sent from the Yuan camp in pursuit. But again, Cao Cao anticipated his opponents' move and had prepared a snare. Horses, equipment and other valuables were discarded and as the enemy troops broke ranks to loot, they were smashed by six hundred elite cavalry. In the chaotic slaughter, the commander Wen Chou was killed. Thus, in the opening moves, Yuan Shao had lost two of his great leaders and his army morale had taken a huge thrashing.
In the aftermath, he reorganised his forces and Liu Bei was sent out to attack Runan, and expose Cao Cao's flank. Ever the strategist, Cao Cao recognised this and wary of fighting under disadvantageous circumstances, commanded a general withdraw to Guandu. At the same time, Cao Ren and Yu Jin were sent to harass the enemy rear. Orders were given for administrators to govern leniently to offset any chance of civilian disruptions in the rear. In the eighth month the Yuan army pushed to Yangwu, directly north of Guandu and began construction on earthen fortifications. The Cao army also began reinforcing their own defences. Both sides harassed each other with ballistas and catapults without effective result. To break the stalemate, it was suggested to Yuan Shao that he use his superior numbers to his advantage and outflank the enemy to attack Xuchang. Yuan, however refused, preferring to wait for the food supply in the Cao army to run out.