I'd say the greatest would be Sun Tzu, but not many people have mentioned the Taliban/ Mujahdeen/ IRA and their leaders. Surely striking fear into your opponents, fighting off the largest super powers using guerrilla tactics, attacking state capitals, spreading propaganda, continuing a war for many years and using 'persuasive' techniques to make people follow you are characteristics of a war leader, no matter what morals they have or don't have.
Also, the chinese dude with the teracotta (sp?) army and the pyramids.
Edit:
To the guy that said Germany wouldn't have won because the US (derp derp) were involved and that they made the atomic bomb, you should know that if Germany had pushed back Russia just once more, they would have had the precious few weeks to finalise their own nucleur arsenal which they had been developing and was almost ready to launch to America. And yes the documents were found that proved how close Hitler was to the arsenal and so on.
Also, to the guy who said Dujek Onearm, you are a legend, those books are fantastic.