The dislike of the rule of the sword which was felt amongst those for whom that sword had been drawn was sure to be felt far more strongly in the Protestant cities of North Germany. Up to Wallenstein's appearance the commercial oligarchies by which those cities were governed, had shown themselves at the best but lukewarm in the Protestant cause. The towns of the south had been the first to desert the Union. The towns of the north had been dragged half against their will into the Danish war. To them the imperial sway was connected by a tradition of centuries with support against the encroachments of the princes. But they had no traditions in favour of an army living at free quarters amongst them, of bullying colonels and hectoring soldiers. Magdeburg braved all the terrors of Wallenstein's anger rather than admit a single company within its walls. Hamburg declared itself ready to submit to the Emperor's authority, but closed its gates against his army. And though Magdeburg might be besieged when there was leisure, Hamburg and the other maritime towns were less easily to be gained. All-powerful on land, Wallenstein's authority ended at low-water mark. The King of Denmark had fled to his islands. The King of Sweden was master of the Baltic. If it was doubtful whether they could set an army in battle array in Germany, at least they could throw provisions and munitions of war into a besieged seaport town. If the Empire was to be secured, these seaports must be brought under the Emperor's authority. [Sidenote: § 5. Wallenstein in possession of the Duchy of Mecklenburg.] Here, therefore, in the midst of the danger Wallenstein determined to plant himself firmly, with the instinctive conviction that the post of danger is the post of power. The two Dukes of Mecklenburg had steadily supported the King of Denmark in his struggle against the Emperor. In 1627, when most of the other states ceased to pay any contributions towards the war, they had continued to fulfil their engagements, and though they now professed their readiness to make their submission, it was Wallenstein's interest to make the most of their treason, and the least of their repentance. In February, 1628, the Emperor, using the rights which he had claimed in the case of the Elector Palatine, declared them to have forfeited their lands and dignities, and placed the Duchies in Wallenstein's hands as a pledge for the payment of military expenses which still remained to be liquidated. It was significant of the change of feeling in Germany that the ecclesiastical electors, who had seen nothing amiss in the deprivation of Frederick, had not a good word to say for this concession to Wallenstein. [Sidenote: § 6. Negotiation with the Hanse Towns.]