Most directly one would say that Animal Farm is an allegory of Stalinism, growing out from the Russian Revolution in 1917. Because it is cast as an animal fable it gives the reader/viewer, some distance from the specific political events. The use of the fable form helps one to examine the certain elements of human nature which can produce a Stalin and enable him to seize power. Orwell, does however, set his fable in familiar events of current history.
Old Major, a eminent pig on the Jones farm, is regarded as the wise superior by the other animals. He has had a strange dream and calls the other animals together to talk about their disastrous situation. Old major declares: "Let us face it, our lives are miserable, laborious and short". He declares in Marxist terms that Man is the problem: "Only get rid of the Man, and the produce of our labour would be our own. Almost overnight we could be rich and free. What then must we do? Why, work night and day, body and soul, for the overthrow of the human race! That is my message to you, comrades. Rebellion!"
The simple, but emotional appeal, gets trough to the uneducated and plain animals and, as in all revolutions, the planning begins in euphoria and idealism. No voice is raised to ask relevant question or call for a considered debate.
The appearance of rats at the meeting raises a question: "Are rats comrades?" A democratic vote results in a ringing "Yes!". And Old Major proclaims, "No animal must ever tyrannise over his own kind. Weak or strong, clever or simple, we are all brothers. All animals are equal!"
It was however generally understood that the pigs were the cleverest of the animals, so the work of organising for the Rebellion fell naturally to them. Especially two pigs take over leadership: Napoleon and Snowball.
The pigs developed Old Major's teaching into a complete system of thought: Animalism. Rules of equality, formality, and hard work was proclaimed and...