Here's how you know Tolstoy was a pretty clever dude. Back in the 19th century, writers were constantly complaining about how hard it was to end a novel. And with good reason. Think about it: you're doing your utmost to describe life as realistically as possible, and then suddenly, just like that, you're supposed to tie it all up neatly: give out rewards to the good characters, punish the bad ones, and, if you're really on the ball, marry them all off to appropriate life partners. Seriously, that's a tall order. Tolstoy? He just bypasses the heck out of that tradition. War and Peace has two separate endings, and neither one follows any kind of novelistic formula.
The first ending deals with the fictional characters. It's really only an ending in the most basic sense of the word, though, meaning the part of their stories that we've been following ends. Nothing gets wrapped up, everything is left loose, and there aren't any rewards or punishments because Tolstoy never divides his characters up into good and bad.
Instead, the whole thing maintains as much realism as possible. Sure, some people get married – but who would have predicted the pairings that end up happening? Just like in life, it's not necessarily the case that these are the perfect matches – maybe they are, maybe they aren't. And rather than ending with marriage, as was typical in a 19th-century novel, Tolstoy shows us some of what happens afterward. We see some kids, we see a little bit of the characters' parenting styles, and we can try to imagine what their lives might be like going forward. In fact, we're pretty much told to do so, since it's hinted strongly that Pierre and his godson Nikolenka are going to end up taking some part in the plot to kill Emperor Alexander a few years after the novel ends.
The second ending is even farther from the traditional novel. It's a long, dense, difficult treatise spelling out Tolstoy's issues with the way history was written at the time. The big fad was the "great man" theory of history. To explain anything, you just had to find the nearest awesome leader and point your finger at him. Tolstoy thinks this kind of thinking is lazy at best and just straight-up dumb at worst.
For him, history needs to expand in every direction: outward, to cover not just the rulers at the top, but also the common people, who actually participate in events; backward, to show how events long ago affect events later on; and inward, to show a person's actions in relation to the forces compelling those actions.
It's way deep, and it goes on for some 50 pages. No way Dickens ever finished a novel that way, we'll tell you that much. Whipping out a philosophical essay about the nature of power to end an already intense book? That takes some real moxie.