Ancient: If the biblical accounts have any truth to them, Joshua's victories in Canaan as he strove to get the Israelites their promised land are incredible. Classical: I really don't know. Hannibal? Maybe some great leader in China or India that I'm unaware of? Hadrian? Dark/Middle: I'd say Belisarius. Renaissance: Not a clue. 1800s onward: Good Lord, too many to choose from! I won't say Napoleon because he let his egomania leave a generation of France's soldiers dead in Russia. Guderian, Rommel, Hancock (underrated by too many imho), Zhukov, Patton, the list goes on. I would say that perhaps the greatest collection of great generals one side ever had at one time was either the CSA during the American civil war or the German army in WWII.