Snowball is the Leader until Napoleon usurps his power. Overall the pigs are the leaders of the animals, in the beginning because they could read and write, and also because it was old major, the prize winning pig, that had the idea. In the end, Napoleon had power because he claimed it, and the animals were still convinced that life under a pig was better than life under a human, even if it was equally as terrible.
THe flag is made from an old green tablecloth (green to represent the fields of England with a hoof and a horn on it. The hoof and horn celebrate animal independence from humans.