The progress of the King of Sweden in Brandenburg and Pomerania, left the new generalissimo no time to lose; and his presence was now urgently called for by those who commanded in that quarter. With all expedition, he collected the imperial troops which were dispersed over the empire; but it required time to obtain from the exhausted and impoverished provinces the necessary supplies. At last, about the middle of winter, he appeared at the head of 20,000 men, before Frankfort on the Oder, where he was joined by Schaumburg. Leaving to this general the defence of Frankfort, with a sufficient garrison, he hastened to Pomerania, with a view of saving Demmin, and relieving Colberg, which was already hard pressed by the Swedes. But even before he had left Brandenburg, Demmin, which was but poorly defended by the Duke of Savelli, had surrendered to the king, and Colberg, after a five months' siege, was starved into a capitulation. As the passes in Upper Pomerania were well guarded, and the king's camp near Schwedt defied attack, Tilly abandoned his offensive plan of operations, and retreated towards the Elbe to besiege Magdeburg. The capture of Demmin opened to the king a free passage into Mecklenburg; but a more important enterprise drew his arms into another quarter. Scarcely had Tilly commenced his retrograde movement, when suddenly breaking up his camp at Schwedt, the king marched his whole force against Frankfort on the Oder. This town, badly fortified, was defended by a garrison of 8,000 men, mostly composed of those ferocious bands who had so cruelly ravaged Pomerania and Brandenburg. It was now attacked with such impetuosity, that on the third day it was taken by storm. The Swedes, assured of victory, rejected every offer of capitulation, as they were resolved to exercise the dreadful right of retaliation. For Tilly, soon after his arrival, had surrounded a Swedish detachment, and, irritated by their obstinate resistance, had cut them in pieces to a man. This cruelty was not forgotten by the Swedes. "New Brandenburg Quarter", they replied to the Imperialists who begged their lives, and slaughtered them without mercy. Several thousands were either killed or taken, and many were drowned in the Oder, the rest fled to Silesia. All their artillery fell into the hands of the Swedes. To satisfy the rage of his troops, Gustavus Adolphus was under the necessity of giving up the town for three hours to plunder.