In the eighth month , Yuan Shao 's army slowly advanced southward from Yangwu .
In the eighth month , Yuan Shao 's army slowly engaged Cao Cao 's men in trench warfare , behind the earthen embankments that both sides made .
In the eighth month , Yuan Shao 's army slowly advanced southward from Yangwu and engaged Cao Cao 's men in trench warfare , behind the earthen embankments that both sides made .