Napoleon manipulates his people with lies about the previous leader, twists past occurrences to look in his favour. Over-works and under-feeds the other animals. Runs them ragged, but they keep working our of manipulation and fear.
It's then found some of the other animals have been in contact with Snowball and when Napoleon finds out he holds a group meeting to discover all who have done this. The animals, one by one, admit to having said contact and are martyred on the spot. There's this huge slaughter. Any remaining animals depart and they're very sad and depressed. Morale is low. They continue to question the authority.
We all question authority at some point, don't we?