How does Animal Farm evoke the Russian Revolution?
Animal Farm is a direct satire and condemnation of the Russian Revolution. It includes allegories for several of the major historical figures of the Revolution, including Karl Marx (Old Major), Leon Trotsky (Snowball), and Joseph Stalin (Napoleon). The underlying brutality and eventual dictatorship of Communism is seen in the constantly-changing rules of Animalism, which allows a double-standard for some and not others. Aside from various major events that parallel real events in Russia, one important aspect of the book is the feeling by the animals that things are going to get better even in the face of obvious evidence to the contrary:
None of the old dreams had been abandoned. The Republic of the Animals which Major had foretold, when the green fields of England should be untrodden by human feet, was still believed in. Some day it was coming: it might not be soon, it might not be with in the lifetime of any animal now living, but still it was coming.
(Orwell, Animal Farm, msxnet.org)
Like Russia, the animals continue to work for the benefit of their leaders and not themselves, believing that it will only be a short time before things become better. Just like in Russia, this never occurred; the leaders grew more powerful, more paranoid, and more cruel until the country collapsed. The Animal Farm is not depicted as collapsing in the book, but it is hinted that it is only a matter of time before the pigs overstep their power and the other animals revolt again.