In his extended allegory of Animal Farm, George Orwell described the causes, action, and conclusion of the Russian Revolution in 1917. Each of the characters mentioned throughout the work stands as a symbol or event that historically existed (the name "Boxer" for the horse, for example, is a nod towards the Boxer Rebellion in China in 1899.)
Napoleon and Snowball in the story represent the actual historical figures of Joseph Stalin (1878-1953) and Leon Trotsky (1879-1940) who started as allies at the beginning of the Russian Revolution overthrowing the Czarist government. After the Revolution, Trotsky had advocated the establishment of an industrial base within Russia and the spread of Communism worldwide; Stalin instead advocated an agrarian economy and the establishment of Communism soley in Russia, his ulterior motives to consolidate his political power, which he achieved quite effectively several years later through purges and starvation. Eventually Stalin was able to coerce Trotsky into exile and had him assassinated, much like the way Napoleon used his dogs to chase Snowball from the farm.