Animal Farm is an allegory for Stalinist Russia

In Manor Farm, a group of animals, primarily the pigs, tires of the farmer's tyrannical rule and Snowflake and Napoleon, the leaders of the pigs, plot to overthrow him. They succeed in expelling the farmer and rename the farm Animal Farm, and for a while try to establish an egalitarian socialist society. Things work well for a while and each animal does his or her share in the society, but Napoleon, who is representative of Joseph Stalin, secretly kidnaps a few puppies and trains them to be his secret police force. Later, Napoleon uses the now large and ferocious dogs to chase Snowflake out and gradually consolidates power. He starts to negotiate with two neighboring farmers and to press more and more work upon the other animals, which he keeps in check with his secret police. Ultimately, Napoleon assumes all the tyrannical characteristics of the farmer that he hated and changes the name of Animal Farm back to Manor Farm.