The CIA obtained the film rights to "Animal Farm" from Orwell's widow, Sonia, after his death and covertly funded the production as anti-Communist propaganda. Some sources assert that the ending of the story was altered by the CIA (in the book, the pigs and humans join forces) to press home their message, but it is equally possible that the more upbeat ending of the movie was an artistic decision, to give the film more audience appeal.
The head of the CIA operation to obtain the film rights was none other than E. Howard Hunt, later famous as Nixon's Watergate burglar. As part of the deal, Sonia Orwell requested that she get to meet her idol, Clark Gable; this was arranged.
A large portion of the budget ($300,000 out of a cost of over $500,000) was supplied by the United States' Central Intelligence Agency, Office of Policy Coordination, through one of its shell corporations, Touchstone Inc.
George Orwell himself stated that had Snowball triumphed over Napoleon, the animals would have fared no better. Using the windmill as an example, Orwell said that Snowball would have poured time and resources into similar pharaonic projects which would have bankrupted the farm.
Producer Louis De Rochemont - best known for his 'March of Time' newsreel series - approached the team of Halas-Batchelor with a view to producing the first ever animated feature aimed specifically at adults. The directors leapt at the chance.