In "Animal Farm", how does Napoleon use propaganda effectively and change history?

Propaganda typically sends a message that fogs truth. In other words, the message might contain accuracies, but it is skewed in order to manipulate its target. For the most part, propaganda was used effectively in Animal Farm because the animals using it played on the fears of others. In the beginning of the book, the pigs wanted to liberate themselves from an oppressive work environment. While Napoleon was in power, he would often tell the other animals that if they did not follow his agenda, the humans would take over and the entire farm would be back where it started. While this may be true, the fact is that the farm is even more oppressive than before Napolean took over. In order to cover this up, Napolean tells them that there must be difficult times now in order for a better future. Again, this is only partially true because as each small goal is attained, another goal is created -- thus perpetuating an oppressive work environment.