I thought I would take a moment to recommend 2 excellent reads by R.F. Delderfield: "Imperial Sunset: The Fall of Napoleon 1813-1814", and "Napoleon's Marshals." I have just finished the latter, and can't help feeling a little melancholy, reading about the various marshals in old age and thinking on their various plights after the guns had grown silent and political winds shifted. In fact, I couldn't help reading both books and being rather swept up by the narratives. The mark of their quality is that even knowing the history, you can't help feeling the shock and disappointment as La Grande Armee and its commander meet their fate, much as you came to share in their triumph and exultation during victory.
As you can tell from the icon, I'm something of a Davout enthusiast, and have owned a copy of "The Iron Marshal" for a number of years. If anyone else can recommend good biographies or memoirs of other marshals, I'd be interested and appreciative. I suppose that I should mention my French is far worse than my German. :-)