When Napoleon begins to have dealings with humans and enters an agreement to sell eggs at so many per week, the animals are no longer working to procure their own best interests but have entered into an economy whose interests are literally defined by the regime. Napoleon clearly does not have the animals' best interests in mind as he forces them to work harder than ever while eating less and all the while he and his cohort dine well, drink liquor, and throw parties.
It is no coincidence that Orwell named this character Napoleon.
His name is reminiscent of the historical Napoleon, who became the all-powerful, autocratic Emperor of the French. Like his French counterpart, Napoleon seems to embody the idea that with power comes corruption. (enotes, Animal Farm character analysis, Napoleon) This quote can be found here: http://www.enotes.com/animal-farm/napoleon
Although the animals do not realize it, they are actually working for Napoleon from the start. Napoleon sees what is likely to happen as a result of Old Major’s speech and Jones’s neglect, and works to capitalize on his reputation for “depth of character” (ch 1). Every move Napoleon makes is designed to slowly cement his power—so slowly in fact that most animals are unaware of it. They think Napoleon is acting in their best interests, and not his own.
Napoleon is cunning and patient. He makes sure that the other animals associate him with leadership and positive things at first. After the animals rebel and kick Jones and the humans out, “Napoleon then led them back to the store-shed and served out a double ration of corn to everybody, with two biscuits for each dog” (ch 2).
Napoleon then leads the animals on a tour of the farmhouse, calls the animals to the harvest, has the “Animal Farm” sign painted, and puts up the Seven Commandments. At the same time, he tells the animals not to worry about where the milk is going. Clearly, the animals were working for Napoleon from the beginning.
Napoleon cleverly allows Snowball and Squealer to remain in the spotlight, quietly working from behind the scenes. For example, he lets Snowball create the ideas, and has the persuasive Squealer serve as his mouthpiece. Meanwhile, he works behind the scenes training the puppies to be his private security force, and working with the pigs to solidify his power.
For more on Napoleon, read here: http://www.enotes.com/animal-farm/napoleon
For the full text of Animal Farm, read here: http://www.george-orwell.org/Animal_Farm/0.html
As the commandment is changed to read: "All animals are equal, but some animals are more equal than others." The pigs are able to rewrite the history of the revolution in such a way as to glorify Napoleon. All of the rules that were instituted to achieve animal equality are violated by the pigs, who eventually even begin to physically resemble the humans.
At first, the animals do feel that they are working for themselves. This results in much better working conditions and better harvests, because they work harder, don't waste anything, and don't steal. But as Napoleon assumes more and more power, the animals have to work harder and make do with less as Napoleon takes advantage of them for his own benefit. He even spends their hard earned money on whiskey!
All of the best things go to Napoleon and to the other pigs. We see this from very early on in the book. If the animals were really working for themselves, they'd all enjoy the fruits of their labor equally. But they're working for Napoleon and the pigs and so the pigs get the best of everything.