In Animal Farm, Orwell demonstrates how a revolution of the sort carried out by the animals (who, of course, are clearly an allegorical reference to the Soviet Union under Stalin) can be manipulated by powerful people (or pigs) to their own ends. Orwell's warning is to some extent against revolution, and he is certainly interested in pointing out the issues that creep into a would-be utopian society. But perhaps his most important point is to emphasize the importance of vigilance against power. Without protections for basic liberties combined with a vigilant populace, even movements begun with the best of intentions can go awry, and eventually might become, as Animal Farm (and the USSR) did, as bad as the society they overthrew. He shows this by illustrating the rise of Napoleon to dictatorship, a process that included the murder of other animals, the marginalization and eventually exile of Snowball, and above all the efforts of Squealer, the propagandist pig who is constantly altering reality to support Napoleon and maintain an atmosphere of fear.