A Wizard In War: The Third Chronicle of the Magnus D'Armand, Rogue Wizard (Chronicles of the Rogue Wizard)

The medieval planet of Maltroit seems to be repeating Earth's bloody history in the worst possible manner. It's up to the Rogue Wizard to give the downtrodden a crash course in democracy, so before you can say "Magna Carta," he's bent the course of history by teaching the nobles the rudiments of democracy, and schooling the peasants in the basics of radical politics.