•Why it earns a slot
Why it earns a slot: it fuses a five-family social novel with a standalone philosophy-of-history treatise, then dares to end the book on the treatise instead of a wedding or a farewell scene.
Five aristocratic families collide with Napoleon's invasion of Russia, and Tolstoy spends the last hundred pages arguing that none of their choices actually mattered.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.