At first as a subordinate to his brother William, who as a Swedish lieutenant-general succeeded to the command, but later as an independent commander, Bernard continued to push his forays over southern Germany; and with the Swedish General Gustav Horn he made in 1633 a successful invasion into Bavaria, which was defended by the imperialist general Count Aldringer. In this year he was granted the former Bishoprics of Würzburg and Bamberg, being granted the title of Duke of Franconia. He installed one of his many brothers as Statthalter, and returned to the wars. A stern Protestant, he exacted heavy contributions from the Catholic cities which he took, and his repeated victories caused him to be regarded by German Protestants as the saviour of their religion. But in 1634 Bernard suffered a great defeat at Nördlingen, losing the best of the Swedish army.