The pigs became the conscience of the other animals and were led by Snowball Brown and David Napoleon along with a sycophant Nick Squealer who urged the other animals to embrace the new Tenets of Animalism with his eloquent grasp of voice while hiding his personal agenda.
Catch up: Part 1
Their rise to power was made possible from the reflective and philosophical Old Major Blair whose premature demise opened the barn door for the new farm order. Though the promises of equality among all animals was at the top of the hierarchy of truth as is always the case the farms critical effort was placed on the back of the workhorse John Q. Boxer whose steady and cooperative persona supported whoever ruled.
The animals saw one advantage that humans do not possess and that is as beasts designed genetically they owed nothing to any God; they were free from the chains of morality. The pigs used this advantage by demanding more and more from the animals while they themselves embraced their singularity and made themselves godlike.
More and more was placed on John Q. whose only response was 'I will work harder' while the piggish triumvirate sorted through the fruits of the productive farm and selected their share before the rest claiming the head of the farm needs it the most.
Once established as the leadership the obvious next step for the pigs was to evolve into what socialism always does and that is dictatorship and each pig took a separate path.
Napoleon dedicated to removing the influence of the mother and father and brainwash the newborn members of the farm while Snowball declared the need for complete energy independence and pushed for the construction of a windmill. Squealer worked both sides and waited for his chance to usurp.