Emperor went straight for Mühlberg, where he found the Elector at nine a.m. on April 24. A bridge of boats was moored to the right bank of the Elbe, but some Spaniards swam the river with swords in their mouths, cut down the guards, and secured the bridge. By it the bulk of the infantry crossed, while the cavalry found a ford higher up. Without attempting to defend his position the Elector commenced a retreat to the north. About sunset the imperialists overtook him and routed his slender forces with great slaughter. John Frederick fought with conspicuous courage, and was brought into the Emperor's presence with blood streaming from a wound in his cheek. Charles was not generous in the hour of victory; he taunted the Elector with his previous disobedience, while Ferdinand demanded his execution. A sentence of death was actually passed, but it was only used to extort the surrender of Wittenberg, which the Spanish troops were afraid to storm. By the capitulation of Wittenberg Maurice received his cousin's electoral dignity, and a considerable slice of his territories, while Sagan and the Voigtland fell to the share of Ferdinand. John Frederick was carried about a prisoner in the Emperor's suite; but no threats could shake his steadfast adherence to the Lutheran faith, and three years later Charles secretly decreed that his detention should last as long as his life.
From the Elector he turned to the Landgrave, whose submission was delayed by the successful resistance of Bremen to Eric of Brunswick and Christopher von Wrisberg, and by the defeat, much more sanguinary than the battle of Mühlberg, which Christopher of Oldenburg and Albrecht of Mansfeld inflicted upon the imperialists near the Drakensberg. But these victories only saved the Baltic lands; in the west Philip could find no support, and after much hesitation he was induced to surrender by Maurice and Joachim of Brandenburg. The two Princes pledged their word to Philip that he should not be imprisoned, but for this they apparently had no warrant. The popular legend that the term ohne einigen Gefängnis (without any imprisonment) was altered by a secretary to ohne ewigen Gefängnis (without perpetual imprisonment) has no satisfactory basis; but it is clear that both Philip and the two Princes understood that the Landgrave should go free, and there were high words between them and Alva, when, after Philip had made his submission (June 20), the Duke placed him under arrest. Such had been Charles' intention throughout; he does not appear to have encouraged any deception, and subsequently the two Princes admitted that the mistake had been theirs. It was an unfortunate mistake for Charles' reputation; but for the rest Philip escaped more lightly than John Frederick, a circumstance which he owed to Maurice, and not to his deserts. In 1550 his term of detention was fixed at fifteen years; he was to dismantle all his fortresses save one, and to give up his artillery; his territories were to remain intact and his people unmolested on account of their religion;
