Old Major the boar gathers the animals of Manor Farm for a meeting. In a dream he had, all animals lived together with no human beings to oppress or control them. He urges the animals to work toward such a paradise. The animals greet Major's vision with enthusiasm. When he dies three nights after the meeting, three younger pigs--Snowball, Napoleon, and Squealer--formulate his main principles into a philosophy called Animalism. One night, the animals defeat their farmer Mr. Jones, and run him off his farm. They rename it Animal Farm. The cart-horse Boxer is the most loyal follower of the cause, adopting the personal philosophy, "I will work harder."
At first, Animal Farm prospers. Snowball teaches the animals to read, and Napoleon takes a group of young puppies to "...educate them in the principles of Animalism." When Mr. Jones reappears to take back his farm, the animals defeat him again, and take the farmer's gun as a token of their victory.
As time passes, however, Napoleon and Snowball increasingly fight over the future of the farm, and struggle with each other for power over the other animals. Snowball schemes to build an electricity-generating windmill, but Napoleon opposes the plan. At the meeting to vote on the project, Snowball gives a great speech. Napoleon then makes a strange noise, and nine attack dogs--the puppies that Napoleon had confiscated in order to "educate"--burst into the barn and chase Snowball away. Napoleon assumes leadership of Animal Farm and declares that from that point on, the pigs alone will make all the decisions--for the good of every animal.
Napoleon quickly changes his mind about the windmill, and the animals work hard to complete it. One day, the windmill toppled after a storm. Napoleon claims Snowball returned to the farm, and sabotaged the windmill.