In George Orwell's Animal Farm, a number of persuasive pigs lead the other farm animals in an effort to overthrow the human owners of Manor Farm. Because the pigs are regarded "as being the cleverest of the animals", they are able to keep the other animals under their hooves, so to speak.
The ideals behind the animals' rebellion were originally set forth by the pig named Major, but after Major's death, these ideals gradually become corrupted. At first, the pigs painted the seven major tenets of their philosophy, Animalism, on the wall of the barn. As time goes on, though, and the pigs become more corrupt, these original Seven Commandments are altered, rewritten, or even erased.
Persuasive speech is the key to the pigs' power and eloquent pigs like Snowball and Squealer, in particular, use subtle arguments to keep the other animals from realizing that they are actually trading one master for another.
As life for the animals who are not pigs becomes increasingly more difficult, the pigs, led by Napoleon, establish a weekly event called a "Spontaneous Demonstration." Of course, because it was organized and held weekly, it was anything but spontaneous. Still, these demonstrations involved a lot of pagentry, singing, and marching, which most of the animals seemed to enjoy. Thus, the animals "were able to forget that their bellies were empty, at least part of the time."
Thus, the pigs manipulate the other animals through clever speech and making them believe that their overthrow of their human masters has given them a freedom that they could not have enjoyed otherwise.