Who leads "The Battle of Cowshed"? What happens to him as a result?
The Battle of Cowshed was led by Snowball, who is declared Animal Hero, First Class, and given a medal. Snowball is a hero for only a short time.
"After the Battle of the Cowshed, Animal Farm is safe from human attack for the time being, due in a large part to Snowball’s military genius"
When Snowball suggests that the animals build a windmill to power the farm to provide better service and comfort to the animals, Napoleon realizes that he has to go. Napoleon realizes that he has competition for absolute control of Animal Farm. He then decides that Snowball must has got to go.
Napoleon does not engage Snowball himself, however, he send in his attack dogs, the puppies he raised, to run Snowball off the farm. He then convinces the other animals that Snowball was not a hero, but a traitor and that he was working against them with the humans.
Napoleon manipulates the truth, lies and convinces the other animals that they did not see Snowball behave like a hero, but was a secret agent for the enemy putting on a good show to foo them.
Snowball is again used as a propaganda tool by Napoleon later in the story and blamed for everything that goes wrong on the farm.