An alternate take on the excellent "Chains" story from BookyBrony.
It would seem silly to ask Callum why he's doing what he's doing. And yet he wouldn't answer "for freedom" if you did. He thinks he's on a mission. A divine mission to deliver his people from slavery after centuries of toiling for their pony masters.
Equestria is on pincushions as this rebel slave leads a band of escaped humans in a war against the forces of Princess Celestia and the Equestrian aristocracy. Part preacher part general his single minded goal pushes an issue that has gone unaddressed for centuries. What's three more years though?