Chapter 3. They overthrow Jones and in Chapter 4 comes the Battle of the Cowshed.
In Chapter 6 of Animal Farm, Napolean uses Snowball as a scapegoat, because he can no longer defend himself now that he has been driven off the farm.
... read the chapter, and you'll find out...
Chapter X ~ see related link below .
In chapter two when they take over manor farm
I believe it was Old Major in Chapter 1 of Animal Farm.