Mollie, the young mare, proves troublesome and resistant to the social order of Animal Farm, keeping forbidden items like sugar lumps and fancy ribbons in her stall and consorting with humans on a neighboring property. Eventually, Mollie disappears from Animal Farm and is reported to be living a more conventional horse’s life near the village of Willingdon.

The winter is very harsh. The animals meet in the barn to plan the coming season, with Snowball and Napoleon emerging as rival and quarrelsome leaders, each with his own following among the animals. A dispute arises over building a windmill on the farm. Snowball argues that a windmill could supply electricity to the farm, thus facilitating electric lights and heating that would make life easier for the animals. Napoleon says that such a project would be impractical and take away time needed for producing food.

The tension between the two rival leaders builds until one day, at a meeting, Napoleon lets loose a group of vicious dogs that chase Snowball from the farm. They are the puppies that Napoleon has been keeping in the loft, now fully grown.

Napoleon immediately takes control of Animal Farm, abolishes the Sunday meetings, and appoints a committee of pigs to manage the farm’s affairs.