Continuing the 'big questions' theme, here's another big one to spark POLITE discussion:
What was Napoleon's biggest mistake?
A few immediately spring to mind - the Continental System, the Peninsular War, the invasion of Russia, the return from Elba.
As before, chose your own parameters for measuring this, and happy posting.

One of Napoleon's overlooked mistakes is in his promotion to marshal of Oudinot, Marmont, and Macdonald after Wagram.