BARNIM XI. (1501-1573), son of Bogislaus X., duke of Pomerania, became duke on his father's death in 1523. He ruled for a time in common with his elder brother George; and after George's death in 1531 he shared the duchy with his nephew Philip I., retaining for himself the duchy of Pomerania-Stettin. In 1529 a treaty was made which freed Pomerania from the supremacy of Brandenburg on condition that if the ducal family became extinct the duchy should revert to Brandenburg. Barnim adopted the Lutheran doctrine and joined the league of Schmal kalden, but took no part in the subsequent war. But he was com pelled to accept the Interim, issued from Augsburg in May 1548. In 1569 Barnim handed over his duchy to his grandnephew, John Frederick.