The possession of Ratisbon, enlarged the projects of the duke, and Bavaria itself now appeared too narrow a field for his bold designs. He determined to penetrate to the frontiers of Austria, to arm the Protestant peasantry against the Emperor, and restore to them their religious liberty. He had already taken Straubingen, while another Swedish army was advancing successfully along the northern bank of the Danube. At the head of his Swedes, bidding defiance to the severity of the weather, he reached the mouth of the Iser, which he passed in the presence of the Bavarian General Werth, who was encamped on that river. Passau and Lintz trembled for their fate; the terrified Emperor redoubled his entreaties and commands to Wallenstein, to hasten with all speed to the relief of the hard-pressed Bavarians. But here the victorious Bernard, of his own accord, checked his career of conquest. Having in front of him the river Inn, guarded by a number of strong fortresses, and behind him two hostile armies, a disaffected country, and the river Iser, while his rear was covered by no tenable position, and no entrenchment could be made in the frozen ground, and threatened by the whole force of Wallenstein, who had at last resolved to march to the Danube, by a timely retreat he escaped the danger of being cut off from Ratisbon, and surrounded by the enemy. He hastened across the Iser to the Danube, to defend the conquests he had made in the Upper Palatinate against Wallenstein, and fully resolved not to decline a battle, if necessary, with that general. But Wallenstein, who was not disposed for any great exploits on the Danube, did not wait for his approach; and before the Bavarians could congratulate themselves on his arrival, he suddenly withdrew again into Bohemia. The duke thus ended his victorious campaign, and allowed his troops their well-earned repose in winter quarters upon an enemy's country.