When you think of Napoleon's invasion of Russia (as I'm sure you often do, doesn't everyone?), you probably think it failed because of the Russian winter, hunger, and the Russians' clever, though somewhat accidental, strategy of leading the Grande Armee deep into their territory, too far from supplies or reinforcements. All those, along with a strange combination of lassitude and hubris on Napoleon's part, certainly played a role. But The Illustrious Dead (Stephan Talty, 2009) gives the lion's share of the credit to typhus, showing how the disease burned its way through the army from the very beginning of the campaign to when the handful of survivors staggered into Germany.
This is a good, readable work of popular military history. I'd recommend it to just about anyone interested in the era--it's straightforward and clear enough for those who haven't read much military history, but the focus on typhus gives a different spin for those who already know Napoleon's campaigns well. And Talty knows how to make nonfiction history read like a page-turning novel.
I've never been an admirer of Napoleon's, but I try very hard to understand why so many people have been, then and now. And sometimes I think I've almost grasped it until I read another account of the invasion of Russia. So much death and destruction for the sake of one man's ambition and hubris.