Why did Cao Cao 's generals prove unworthy for war at the Battle of Red Cliffs according to Zhou Yu ?
Cao Cao suffered a drastic defeat at the Battle of Red Cliffs and was forced to retreat north back to Jiangling ( 江陵 , located in present - day Jingjiang 荆江 , not to be confused with present - day Jiangling County , Hubei ) .