Albert, Duke of Prussia

Albert became grand master of the Teutonic Knights in 1510, appointed in a bid to smooth relations with Poland - ironic, given his great-grandfather Jogaila had crushed the order at Grunwald. He reversed the Knights' long decline through shrewd administration, but Luther's ideas found him sympathetic. In 1525 he broke with Rome and the Holy Roman Empire, secularizing the Teutonic lands into the hereditary Duchy of Prussia and paying homage to his uncle, the Polish king, under the Treaty of Kraków. The move made him the first European ruler to establish Lutheranism as official state religion. He confiscated Catholic holdings to fund his court and placate the nobles, founded the University of Königsberg in 1544, and joined Protestant coalitions plotting against Charles V. The final years turned sour - church coffers emptied, taxes rose, peasants rebelled, and court intrigues around favourites like Johann Funck stripped him of real authority. He died at Tapiau in 1568, nearly six decades into a rule that had planted Protestantism as a territorial force.