Yuan Shao used Guo Tu 's idea .
Yuan Shao sent Zhang He and Gao Lan to lead his main army to attack Cao Cao 's main camp at Guandu , while only sending a small cavalry unit to reinforce Wuchao .
Yuan Shao used Guo Tu 's idea and sent Zhang He and Gao Lan to lead his main army to attack Cao Cao 's main camp at Guandu , while only sending a small cavalry unit to reinforce Wuchao .