Napoleon is a a badass still. Here is my favorite battle of his:
But I agree with
@Removed , it was the French and German hubris that lost them both wars. If only Napoleon had stayed in Poland/Prussia and consolidated his gains he would've been set. Same for the Germans. They should've knocked out Britain first and consolidated France first. Arrogance kills.
Funnily enough, great generals, Alexander, Napoleon, Hannibal, Khalid bin Walid, etc make terrible governors but excellent commanders.
They just don't know when to stop. Even Caeser in the end was planning a campaign in Egypt/Middle East.
Consolidating your gains is much harder then beating an army or two.