Even Lower Saxony, encouraged by the progress of the king, ventured to raise its head from the disasters of the unfortunate Danish war. They held a congress at Hamburg, and resolved upon raising three regiments, which they hoped would be sufficient to free them from the oppressive garrisons of the Imperialists. The Bishop of Bremen, a relation of Gustavus Adolphus, was not content even with this; but assembled troops of his own, and terrified the unfortunate monks and priests of the neighbourhood, but was quickly compelled by the imperial general, Count Gronsfeld, to lay down his arms. Even George, Duke of Lunenburg, formerly a colonel in the Emperor's service, embraced the party of Gustavus, for whom he raised several regiments, and by occupying the attention of the Imperialists in Lower Saxony, materially assisted him. But more important service was rendered to the king by the Landgrave William of Hesse Cassel, whose victorious arms struck with terror the greater part of Westphalia and Lower Saxony, the bishopric of Fulda, and even the Electorate of Cologne. It has been already stated that immediately after the conclusion of the alliance between the Landgrave and Gustavus Adolphus at Werben, two imperial generals, Fugger and Altringer, were ordered by Tilly to march into Hesse, to punish the Landgrave for his revolt from the Emperor. But this prince had as firmly withstood the arms of his enemies, as his subjects had the proclamations of Tilly inciting them to rebellion, and the battle of Leipzig presently relieved him of their presence. He availed himself of their absence with courage and resolution; in a short time, Vach, Muenden and Hoexter surrendered to him, while his rapid advance alarmed the bishoprics of Fulda, Paderborn, and the ecclesiastical territories which bordered on Hesse. The terrified states hastened by a speedy submission to set limits to his progress, and by considerable contributions to purchase exemption from plunder. After these successful enterprises, the Landgrave united his victorious army with that of Gustavus Adolphus, and concerted with him at Frankfort their future plan of operations.