In Chapter 6 of the book Animal Farm, when the animals are up, they discovered that the windmill was destroyed. Napoleon, being the leader of the pack, blames his co-leader Snowball. He thought that Snowball betrayed them in their revolution against Mr. Jones and even put a reward of half a bushel of apples to anyone who will catch him. But in reality, the readers of the story know that it is not Snowball that destroyed the windmill but the weather.
Napoleon took the opportunity to destroy Snowball’s reputation to the other animals that Snowball is an enemy. Napoleon is against Snowball’s idea of educating the old animals and building committees that is why he wanted to get rid of Snowball in the Animal Farm.