Its good to remember that War and Peace is first and foremost, a piece of fiction - historical fiction, but fiction. Meant to entertain and enthrall its reader, and perhaps, yes, present the author's interpretation of history and events. Inaccurate, revisionist or divergent though they may be.

From this alone I'd caution against using Tolstoy's War and Peace in an attempt to understand the Napoleonic era, even in a supplementary manner. This is especially given the author's run-ins with the Second French Empire as he fought opposite them as a Russian artillery officer (Orlando, Figes, *Crimean War: A History). I'd suggest this probably colored his opinion considerably on an era marked by a man who's reputation, in other parts of Europe, was beginning to go on the mend.

That being said, War and Peace is often touted for its painstaking attempts at realism, and its evident that Tolstoy did his homework. Given that he openly admits to being a historical revisionist, and in the course of the book's many intros and prefaces, outright dismisses the (at the time) current view of military history and social history of the era...well, let's just say that a book is often a mouthpiece for the author - and War and Peace is no different. In his mind, it certainly was a depiction of the truth; but in absolute terms, I wouldn't cite it in an essay.