Nothing could be more reasonable than this demand. The services which Gustavus had lately rendered the Elector, by expelling the Imperialists from Brandenburg, claimed his gratitude, while the past conduct of the Swedes in Germany entitled them to confidence. But by the surrender of his fortresses, the Elector would in some measure make the King of Sweden master of his country; besides that, by such a step, he must at once break with the Emperor, and expose his States to his future vengeance. The Elector's struggle with himself was long and violent, but pusillanimity and self-interest for awhile prevailed. Unmoved by the fate of Magdeburg, cold in the cause of religion and the liberties of Germany, he saw nothing but his own danger; and this anxiety was greatly stimulated by his minister Von Schwartzenburgh, who was secretly in the pay of Austria. In the mean time, the Swedish troops approached Berlin, and the king took up his residence with the Elector. When he witnessed the timorous hesitation of that prince, he could not restrain his indignation: "My road is to Magdeburg," said he; "not for my own advantage, but for that of the Protestant religion. If no one will stand by me, I shall immediately retreat, conclude a peace with the Emperor, and return to Stockholm. I am convinced that Ferdinand will readily grant me whatever conditions I may require. But if Magdeburg is once lost, and the Emperor relieved from all fear of me, then it is for you to look to yourselves and the consequences." This timely threat, and perhaps, too, the aspect of the Swedish army, which was strong enough to obtain by force what was refused to entreaty, brought at last the Elector to his senses, and Spandau was delivered into the hands of the Swedes.
The king had now two routes to Magdeburg; one westward led through an exhausted country, and filled with the enemy's troops, who might dispute with him the passage of the Elbe; the other more to the southward, by Dessau and Wittenberg, where bridges were to be found for crossing the Elbe, and where supplies could easily be drawn from Saxony. But he could not avail himself of the latter without the consent of the Elector, whom Gustavus had good reason to distrust. Before setting out on his march, therefore, he demanded from that prince a free passage and liberty for purchasing provisions for his troops. His application was refused, and no remonstrances could prevail on the Elector to abandon his system of neutrality. While the point was still in dispute, the news of the dreadful fate of Magdeburg arrived.
Tilly announced its fall to the Protestant princes in the tone of a conqueror, and lost no time in making the most of the general consternation. The influence of the Emperor, which had sensibly declined during the rapid progress of Gustavus, after this decisive blow rose higher than ever; and the change was speedily visible in the imperious tone he adopted towards the Protestant states. The decrees of the Confederation of Leipzig were annulled by a proclamation, the Convention itself suppressed by an imperial decree, and all the refractory states threatened with the fate of Magdeburg. As the executor of this imperial mandate, Tilly immediately ordered troops to march against the Bishop of Bremen, who was a member of the Confederacy, and had himself enlisted soldiers. The terrified bishop immediately gave up his forces to Tilly, and signed the revocation of the acts of the Confederation. An imperial army, which had lately returned from Italy, under the command of Count Furstenberg, acted in the same manner towards the Administrator of Wirtemberg. The duke was compelled to submit to the Edict of Restitution, and all the decrees of the Emperor, and even to pay a monthly subsidy of 100,000 dollars, for the maintenance of the imperial troops. Similar burdens were inflicted upon Ulm and Nuremberg, and the entire circles of Franconia and Swabia. The hand of the Emperor was stretched in terror over all Germany. The sudden preponderance, more in appearance, perhaps, than in reality, which he had obtained by this blow, carried him beyond the bounds even of the moderation which he had hitherto observed, and misled him into hasty and violent measures, which at last turned the wavering resolution of the German princes in favour of Gustavus Adolphus. Injurious as the immediate consequences of the fall of Magdeburg were to the Protestant cause, its remoter effects were most advantageous. The past surprise made way for active resentment, despair inspired courage, and the German freedom rose, like a phoenix, from the ashes of Magdeburg.
Among the princes of the Leipzig Confederation, the Elector of Saxony and the Landgrave of Hesse were the most powerful; and, until they were disarmed, the universal authority of the Emperor was unconfirmed. Against the Landgrave, therefore, Tilly first directed his attack, and marched straight from Magdeburg into Thuringia. During this march, the territories of Saxe Ernest and Schwartzburg were laid waste, and Frankenhausen plundered before the very eyes of Tilly, and laid in ashes with impunity. The unfortunate peasant paid dear for his master's attachment to the interests of Sweden. Erfurt, the key of Saxony and Franconia, was threatened with a siege, but redeemed itself by a voluntary contribution of money and provisions. From thence, Tilly despatched his emissaries to the Landgrave, demanding of him the immediate disbanding of his army, a renunciation of the league of Leipzig, the reception of imperial garrisons into his territories and fortresses, with the necessary contributions, and the declaration of friendship or hostility. Such was the treatment which a prince of the Empire was compelled to submit to from a servant of the Emperor. But these extravagant demands acquired a formidable weight from the power which supported them; and the dreadful fate of Magdeburg, still fresh in the memory of the Landgrave, tended still farther to enforce them. Admirable, therefore, was the intrepidity of the Landgrave's answer: "To admit foreign troops into his capital and fortresses, the Landgrave is not disposed; his troops he requires for his own purposes; as for an attack, he can defend himself. If General Tilly wants money or provisions, let him go to Munich, where there is plenty of both." The irruption of two bodies of imperial troops into Hesse Cassel was the immediate result of this spirited reply, but the Landgrave gave them so warm a reception that they could effect nothing; and just as Tilly was preparing to follow with his whole army, to punish the unfortunate country for the firmness of its sovereign, the movements of the King of Sweden recalled him to another quarter.
Gustavus Adolphus had learned the fall of Magdeburg with deep regret; and the demand now made by the Elector, George William, in terms of their agreement, for the restoration of Spandau, greatly increased this feeling. The loss of Magdeburg had rather augmented than lessened the reasons which made the possession of this fortress so desirable; and the nearer became the necessity of a decisive battle between himself and Tilly, the more unwilling he felt to abandon the only place which, in the event of a defeat, could ensure him a refuge. After a vain endeavour, by entreaties and representations, to bring over the Elector to his views, whose coldness and lukewarmness daily increased, he gave orders to his general to evacuate Spandau, but at the same time declared to the Elector that he would henceforth regard him as an enemy.
To give weight to this declaration, he appeared with his whole force before Berlin. "I will not be worse treated than the imperial generals," was his reply to the ambassadors whom the bewildered Elector despatched to his camp. "Your master has received them into his territories, furnished them with all necessary supplies, ceded to them every place which they required, and yet, by all these concessions, he could not prevail upon them to treat his subjects with common humanity. All that I require of him is security, a moderate sum of money, and provisions for my troops; in return, I promise to protect his country, and to keep the war at a distance from him. On these points, however, I must insist; and my brother, the Elector, must instantly determine to have me as a friend, or to see his capital plundered." This decisive tone produced a due impression; and the cannon pointed against the town put an end to the doubts of George William. In a few days, a treaty was signed, by which the Elector engaged to furnish a monthly subsidy of 30,000 dollars, to leave Spandau in the king's hands, and to open Custrin at all times to the Swedish troops. This now open alliance of the Elector of Brandenburg with the Swedes, excited no less displeasure at Vienna, than did formerly the similar procedure of the Duke of Pomerania; but the changed fortune which now attended his arms, obliged the Emperor to confine his resentment to words.