What specific events lead to Snowball's expulsion from the farm in Animal Farm?
Snowball's eviction from Animal Farm comes suddenly and it is a surprise to most of the animals. It occurs on the day of Napoleon's and Snowball's speeches prior to a vote by the animals concerning the construction of the windmill. Napoleon and Snowball had previously disagreed about the defense of the farm: Snowball favored sending pigeons outside the farm to spread the word of rebellion to other animals on other farms. Napoleon believed the animals should defend themselves with human weapons. Snowball made an impassioned plea to the other animals, explaining his reasons for building the windmill. Napoleon took only 30 seconds to make his speech, condemning the windmill as "nonsense." Snowball followed with another speech, and this time it swayed the animals to his side.
Until now the animals had been about equally divided in their sympathies, but in a moment Snowball's eloquence had carried them away.
At that point, Napoleon "uttered a high-pitch whimper of a kind no one had ever heard him utter before." "Nine enormous dogs" suddenly appeared, and they chased the frightened Snowball, who managed to barely elude them before finding a hole in the hedge that allowed him to escape. He was never seen again.