The story opens with a meeting of all the animals on a farm where they are mistreated by their owner. Old Major, the big pig, gives a persuasive speech about rebelling and taking over the farm. He then sings them a song called Beasts of England, where it talks about animals being free from man. He persuades all the farm animals to want to rebel through fear and thoughts of a utopia.
Boxer, the large horse, is the best worker on the farm.
Old Major dies, but his speech sticks with the animals. They rebel against their farmer, and establish animal farm, a utopia where all animals are free of man and treated equally. But the pigs, who are the brains of animal farm, start to gain special privileges, such as better food. Most of the animals just rub it off.
Mr. Jones attempts to take back his farm with the help of a few other local farmers. Snowball the pig gets the animals ready for battle. Using tactics formerly used by Julius Caesar, the animals are able to drive Jones and his farmers back out of animal farm. The animals decide to commemorate the event by naming it "the battle of cowshed" and by firing Jones's gun off twice a year. Once on the day they rebelled, and the next on the day they won the battle.
Snowball and Napoleon are butting heads about building a windmill. Snowball convinces the animals to want to build a windmill, so Napoleon has nine guard dogs chase Snowball off of the farm. Napoleon takes full power of the farm and rules by fear. The animals' working conditions are worsened. Napoleon is a bad ruler, making his life better for himself and the pigs, and worse for the animals. He creates loopholes in the commandments. He also decides to have the animals build the windmill.
Animal farm experiences bad harvests, cutting the food rations for the animals very low.
Frederick, the neighboring farmer, comes prepared for battle with other men and a lot of guns. The animals fight back, but due to Napoleons bad military leadership, most are wounded and a handful are killed. Finally the animals retreat to the barn, and watch as the people blow up their newly finished windmill. Boxer is wounded, and it is hard for him to recover. One day Boxer falls and cannot get up. After a couple of days, Napoleon sends him to the horse slaughterer.
He is going to the vet!
Years pass and animal farm becomes successful again, but the animals are still being underfed while the pigs are getting fatter and fatter. One day, Napoleon and all the pigs come marching out on two legs, breaking another commandment. The animals are terrified and go to check the commandments. One commandment remains. "All animals are equal, but some more than others." Napoleon hosts the human farmers and when a fight erupts, the animals can't tell which is pig and which is human.