After Duke Bernard died in 1434, his eldest son, Otto became the ruling prince. In 1446 he was followed by his brother, Frederick the Pious, who abdicated, however, in 1457 in favour of his sons, Bernard and Otto, in order to enter the Franciscan abbey at Celle. After both brothers had died in 1464 and 1471 respectively, Frederick the Pious left the abbey again in order to hold the reins of power for his 3-year old nephew, Henry the Middle, the son of Otto of Lüneburg and Anna of Nassau.