These two kings vied with each other for the honour of defending Lower Saxony, and of opposing the formidable power of Austria. Each offered to raise a well-disciplined army, and to lead it in person. His victorious campaigns against Moscow and Poland gave weight to the promises of the King of Sweden. The shores of the Baltic were full of the name of Gustavus. But the fame of his rival excited the envy of the Danish monarch; and the more success he promised himself in this campaign, the less disposed was he to show any favour to his envied neighbour. Both laid their conditions and plans before the English ministry, and Christian IV. finally succeeded in outbidding his rival. Gustavus Adolphus, for his own security, had demanded the cession of some places of strength in Germany, where he himself had no territories, to afford, in case of need, a place of refuge for his troops. Christian IV. possessed Holstein and Jutland, through which, in the event of a defeat, he could always secure a retreat.
Eager to get the start of his competitor, the King of Denmark hastened to take the field. Appointed generalissimo of the circle of Lower Saxony, he soon had an army of 60,000 men in motion; the administrator of Magdeburg, and the Dukes of Brunswick and Mecklenburgh, entered into an alliance with him. Encouraged by the hope of assistance from England, and the possession of so large a force, he flattered himself he should be able to terminate the war in a single campaign.
At Vienna, it was officially notified that the only object of these preparations was the protection of the circle, and the maintenance of peace. But the negociations with Holland, England, and even France, the extraordinary exertions of the circle, and the raising of so formidable an army, seemed to have something more in view than defensive operations, and to contemplate nothing less than the complete restoration of the Elector Palatine, and the humiliation of the dreaded power of Austria.
After negociations, exhortations, commands, and threats had in vain been employed by the Emperor in order to induce the King of Denmark and the circle of Lower Saxony to lay down their arms, hostilities commenced, and Lower Germany became the theatre of war. Count Tilly, marching along the left bank of the Weser, made himself master of all the passes as far as Minden. After an unsuccessful attack on Nieuburg, he crossed the river and overran the principality of Calemberg, in which he quartered his troops. The king conducted his operations on the right bank of the river, and spread his forces over the territories of Brunswick, but having weakened his main body by too powerful detachments, he could not engage in any enterprise of importance. Aware of his opponent's superiority, he avoided a decisive action as anxiously as the general of the League sought it.
With the exception of the troops from the Spanish Netherlands, which had poured into the Lower Palatinate, the Emperor had hitherto made use only of the arms of Bavaria and the League in Germany. Maximilian conducted the war as executor of the ban of the empire, and Tilly, who commanded the army of execution, was in the Bavarian service. The Emperor owed superiority in the field to Bavaria and the League, and his fortunes were in their hands. This dependence on their goodwill, but ill accorded with the grand schemes, which the brilliant commencement of the war had led the imperial cabinet to form.
However active the League had shown itself in the Emperor's defence, while thereby it secured its own welfare, it could not be expected that it would enter as readily into his views of conquest. Or, if they still continued to lend their armies for that purpose, it was too much to be feared that they would share with the Emperor nothing but general odium, while they appropriated to themselves all advantages. A strong army under his own orders could alone free him from this debasing dependence upon Bavaria, and restore to him his former pre-eminence in Germany. But the war had already exhausted the imperial dominions, and they were unequal to the expense of such an armament. In these circumstances, nothing could be more welcome to the Emperor than the proposal with which one of his officers surprised him.
This was Count Wallenstein, an experienced officer, and the richest nobleman in Bohemia. From his earliest youth he had been in the service of the House of Austria, and several campaigns against the Turks, Venetians, Bohemians, Hungarians, and Transylvanians had established his reputation. He was present as colonel at the battle of Prague, and afterwards, as major-general, had defeated a Hungarian force in Moravia. The Emperor's gratitude was equal to his services, and a large share of the confiscated estates of the Bohemian insurgents was their reward. Possessed of immense property, excited by ambitious views, confident in his own good fortune, and still more encouraged by the existing state of circumstances, he offered, at his own expense and that of his friends, to raise and clothe an army for the Emperor, and even undertook the cost of maintaining it, if he were allowed to augment it to 50,000 men. The project was universally ridiculed as the chimerical offspring of a visionary brain; but the offer was highly valuable, if its promises should be but partially fulfilled. Certain circles in Bohemia were assigned to him as depots, with authority to appoint his own officers. In a few months he had 20,000 men under arms, with which, quitting the Austrian territories, he soon afterwards appeared on the frontiers of Lower Saxony with 30,000. The Emperor had lent this armament nothing but his name. The reputation of the general, the prospect of rapid promotion, and the hope of plunder, attracted to his standard adventurers from all quarters of Germany; and even sovereign princes, stimulated by the desire of glory or of gain, offered to raise regiments for the service of Austria.
Now, therefore, for the first time in this war, an imperial army appeared in Germany;-an event which if it was menacing to the Protestants, was scarcely more acceptable to the Catholics. Wallenstein had orders to unite his army with the troops of the League, and in conjunction with the Bavarian general to attack the King of Denmark. But long jealous of Tilly's fame, he showed no disposition to share with him the laurels of the campaign, or in the splendour of his rival's achievements to dim the lustre of his own. His plan of operations was to support the latter, but to act entirely independent of him. As he had not resources, like Tilly, for supplying the wants of his army, he was obliged to march his troops into fertile countries which had not as yet suffered from war. Disobeying, therefore, the order to form a junction with the general of the League, he marched into the territories of Halberstadt and Magdeburg, and at Dessau made himself master of the Elbe. All the lands on either bank of this river were at his command, and from them he could either attack the King of Denmark in the rear, or, if prudent, enter the territories of that prince.
Christian IV. was fully aware of the danger of his situation between two such powerful armies. He had already been joined by the administrator of Halberstadt, who had lately returned from Holland; he now also acknowledged Mansfeld, whom previously he had refused to recognise, and supported him to the best of his ability. Mansfeld amply requited this service. He alone kept at bay the army of Wallenstein upon the Elbe, and prevented its junction with that of Tilly, and a combined attack on the King of Denmark. Notwithstanding the enemy's superiority, this intrepid general even approached the bridge of Dessau, and ventured to entrench himself in presence of the imperial lines. But attacked in the rear by the whole force of the Imperialists, he was obliged to yield to superior numbers, and to abandon his post with the loss of 3,000 killed. After this defeat, Mansfeld withdrew into Brandenburg, where he soon recruited and reinforced his army; and suddenly turned into Silesia, with the view of marching from thence into Hungary; and, in conjunction with Bethlen Gabor, carrying the war into the heart of Austria. As the Austrian dominions in that quarter were entirely defenceless, Wallenstein received immediate orders to leave the King of Denmark, and if possible to intercept Mansfeld's progress through Silesia.