Napoleon takes Prince Andrei prisoner! Well now this is one Burger King of a coincidence but it's such a good story and so well told, who cares? Tolstoy uses this to show how Andrei has changed, from naive hero-worshipper to a man of profound wisdom:
Though five minutes earlier Prince Andrei had been able to say a few words to the soldiers transporting him, now, with his eyes fixed directly on Napoleon, he was silent... To him at that moment all the interests that occupied Napoleon seemed so insignificant, his hero himelf seemed so petty to him, with his petty vanity and joy in victory, compared with that lofty, just, and kindly sky, which he had seen and understood, that he was unable to answer him.
Tolstoy's characters change, oftentimes dramatically, and yet always believably. This change, evolution of character, is for me, as a reader, extremely engaging. So now when I think of my own writing, I want to more carefully ask, have my characters changed? If not, why? And / or, what if they were to change?
p. 293 Tolstoy mentions the little golden icon Princess Marya had given her brother-- the French soldiers take it from him, but then, seeing how Napoleon treated Prince Andrei, they return it. So that's a mighty heavy dose of symbolism... but what the hell. It works.