original_query: What did Cao Cao do after taking advantage of the internal conflict among Ma Chao's subordinates?
query: What did Cao Cao do after taking advantage of the internal conflict among Ma Chao and Han Sui?
answer: After exploiting the discord between Ma Chao and Han Sui, Cao Cao launched a surprise attack, resulting in a major victory.  Cheng Yi, Li Kan, and others were killed, Yang Qiu fled, and Ma Chao and Han Sui retreated.