The Teutonic Knights were a German military religious order founded (1190-91) during the siege of Acre in the Third Crusade. Originally only Germans of noble birth were admissible to the order. Previously known as the Order of the Knights of the Hospital of St. Mary of the Teutons in Jerusalem, monastic vows of poverty, chastity, and obedience were taken.
The order gained prominence under Hermann von Salza after its move to Eastern Europe. After various crusades including a successful 50 year campaign against Prussia, the Knights founded numerous towns and fortresses. The order was strongly centralized, and its administration and colonization laid the foundation of the Prussian state. The knights administered their lands from Marienburg, but they granted considerable freedom to the cities. After continued warfare with Poland, the knights were forced to cede West Prussia and Pomerelia to Poland, retaining only East Prussia as a Polish fief. Their capital was transferred to Königsberg in East Prussia. The fatal blow to the order was delivered in 1525 by its own grand master, Albert of Brandenburg, who accepted the Reformation, declared Prussia a secular duchy, and was invested as duke by Sigismund I of Poland.