Well, War and Peace seems to me to be about fate; and also history, which is a highly related topic (for Tolstoy, they are more or less the same thing). He is anxious to be done with the Carlyle's Great Man Theory. The supposedly great men of history just aren't all that important in War and Peace. Napoleon thinks he's a military genius, but his orders aren't really even reaching his own men. The French and Russian troops are just doing what they have to do based on what's happening in their little part of the battlefield. And Kutuzov isn't really pursuing some kind of grand strategy. He's just doing what he has to do every time the French beat him, which is mostly just running away. There is this rather moving scene in which Kutuzov, who's not the most emotional man in the world and not the smartest, learns that Napoleon has (quite foolishly) withdrawn from Moscow. He turns to an icon at the back of the room and silently weeps because he FINALLY sees how he can (maybe) defeat him. The implication is that he didn't really have a plan before that, and the one he eventually adopted (the one that won the war) was handed to him by fate.
Previously, many Europeans had thought of fate in Augustinian terms. It was like a boulder crashing down a mountainside, partly carried by the force of its own trajectory (in effect, the consequences of one's prior choices) and partly being directed by or reacting against landscape features (events, ideas, people, crises). This is still a common way to look at things. I just reviewed a book called Pachinko in the Write a Book Review forum. The writer put an East Asian spin on things, but much of it was just a rehash of Augustine's ideas about fate.
But for Tolstoy, fate involves microscopic interactions between an interconnected humanity. It is like a universal web. When a constituent part (an individual) acts it affects others, and their actions affect others and others and others in vast radiations. Although he doesn't use the metaphor, it is like a Ouija board. You know how several people can place their fingers on Ouija board planchette and, although none is aware of it, each is interacting with or against the tiny movements of the others so that the planchette sails off on a course independent of all of them. That is how Tolstoy (at least at that time in his life) saw fate and history. It was (and remains) a challenge to the Homeric ideal that became central to western thought.