How do the animals discover the truth of what has happened and what is the pigs explanation in animal farm?

In George Orwell's "Animal Farm," the animals gradually discover the truth about the pigs' manipulation through their experiences and observations, particularly as they notice the discrepancies between the original commandments and the pigs' actions. The pigs, especially Napoleon, explain their actions by claiming that they are acting in the animals' best interests and that the challenges they face require certain sacrifices. They continually alter the commandments to justify their behavior, ultimately leading the animals to doubt their memories and accept the pigs' distorted version of reality. This manipulation culminates in the chilling realization that the pigs have become indistinguishable from the humans they once overthrew.