How does Napoleon use his power for evil in Animal Farm?

Napoleon uses his power to benefit himself at the expense of the other animals. By the end of the book, he and the other pigs are walking around on their back legs like humans, drinking alcohol, gambling, treating themselves to lavish meals when the rest of the animals are nearly starving, and generally behaving in a way that is totally inconsistent with the ideals of Animal Farm (i.e., they are acting like Man). So Napoleon...

Napoleon uses his power to benefit himself at the expense of the other animals. By the end of the book, he and the other pigs are walking around on their back legs like humans, drinking alcohol, gambling, treating themselves to lavish meals when the rest of the animals are nearly starving, and generally behaving in a way that is totally inconsistent with the ideals of Animal Farm (i.e., they are acting like Man). So Napoleon and the pigs are obviously corrupted. But the issue of power goes beyond such abuses. Napoleon becomes a character who seeks and uses power for its own ends. The pigs alter the Seven Commandments to suit their needs. They "rewrite" history to persuade the other animals that Snowball was the enemy of Animal Farm all along. Napoleon holds vicious purges that murder dozens of innocent animals. All of this is done to augment their own power. This is a central theme, or a sort of moral, of Animal Farm as well as Orwell's other great novel 1984: power, if left unchecked, will only grow destructive.