How did Napoleon and Squealer control the animals?
Napoleon and Squealer control the other animals through a combination of information control and the use of terror. From the first days of Animal Farm, they keep certain privileges (milk and apples) to themselves, and persuade the other animals that if they are not allowed to feast on these treats, that Animal Farm will collapse. Snowball is driven from the farm as a criminal, and Napoleon and Squealer take his idea to build a windmill and make it their own, convincing the animals that it was their idea all along. As they take more and more power and privilege, they alter the seven commandments to justify it. Napoleon purge many of their potential enemies, including some young porkers and hens who refuse to give up their eggs, by setting the dogs he has raised to be killers on them. Through these policies, and, to some extent, with the acquiescence of the other animals, they are able to exert considerable power over Animal Farm and Napoleon emerges as a totalitarian leader, no different than the people they fought to overthrow.