At his approach, the enemy retired to the Lake of Constance, but only to show the Swedes the road into a district hitherto unvisited by war.
A post on the entrance to Switzerland, would be highly serviceable to the Swedes, and the town of Kostnitz seemed peculiarly well fitted to be a point of communication between him and the confederated cantons.
Accordingly, Gustavus Horn immediately commenced the siege of it;but destitute of artillery, for which he was obliged to send to Wirtemberg, he could not press the attack with sufficient vigour, to prevent the enemy from throwing supplies into the town, which the lake afforded them convenient opportunity of doing. He, therefore, after an ineffectual attempt, quitted the place and its neighbourhood, and hastened to meet a more threatening danger upon the Danube.
At the Emperor's instigation, the Cardinal Infante, the brother of Philip IV. of Spain, and the Viceroy of Milan, had raised an army of 14,000 men, intended to act upon the Rhine, independently of Wallenstein, and to protect Alsace. This force now appeared in Bavaria, under the command of the Duke of Feria, a Spaniard; and, that they might be directly employed against the Swedes, Altringer was ordered to join them with his corps. Upon the first intelligence of their approach, Horn had summoned to his assistance the Palsgrave of Birkenfeld, from the Rhine; and being joined by him at Stockach, boldly advanced to meet the enemy's army of 30,000 men.
The latter had taken the route across the Danube into Swabia, where Gustavus Horn came so close upon them, that the two armies were only separated from each other by half a German mile.
But, instead of accepting the offer of battle, the Imperialists moved by the Forest towns towards Briesgau and Alsace, where they arrived in time to relieve Breysack, and to arrest the victorious progress of the Rhinegrave, Otto Louis. The latter had, shortly before, taken the Forest towns, and, supported by the Palatine of Birkenfeld, who had liberated the Lower Palatinate and beaten the Duke of Lorraine out of the field, had once more given the superiority to the Swedish arms in that quarter.
He was now forced to retire before the superior numbers of the enemy;but Horn and Birkenfeld quickly advanced to his support, and the Imperialists, after a brief triumph, were again expelled from Alsace.
The severity of the autumn, in which this hapless retreat had to be conducted, proved fatal to most of the Italians; and their leader, the Duke of Feria, died of grief at the failure of his enterprise.
In the mean time, Duke Bernard of Weimar had taken up his position on the Danube, with eighteen regiments of infantry and 140 squadrons of horse, to cover Franconia, and to watch the movements of the Imperial-Bavarian army upon that river. No sooner had Altringer departed, to join the Italians under Feria, than Bernard, profiting by his absence, hastened across the Danube, and with the rapidity of lightning appeared before Ratisbon. The possession of this town would ensure the success of the Swedish designs upon Bavaria and Austria;it would establish them firmly on the Danube, and provide a safe refuge in case of defeat, while it alone could give permanence to their conquests in that quarter. To defend Ratisbon, was the urgent advice which the dying Tilly left to the Elector; and Gustavus Adolphus had lamented it as an irreparable loss, that the Bavarians had anticipated him in taking possession of this place. Indescribable, therefore, was the consternation of Maximilian, when Duke Bernard suddenly appeared before the town, and prepared in earnest to besiege it.
The garrison consisted of not more than fifteen companies, mostly newly-raised soldiers; although that number was more than sufficient to weary out an enemy of far superior force, if supported by well-disposed and warlike inhabitants. But this was not the greatest danger which the Bavarian garrison had to contend against.
The Protestant inhabitants of Ratisbon, equally jealous of their civil and religious freedom, had unwillingly submitted to the yoke of Bavaria, and had long looked with impatience for the appearance of a deliverer. Bernard's arrival before the walls filled them with lively joy; and there was much reason to fear that they would support the attempts of the besiegers without, by exciting a tumult within. In this perplexity, the Elector addressed the most pressing entreaties to the Emperor and the Duke of Friedland to assist him, were it only with 5,000 men. Seven messengers in succession were despatched by Ferdinand to Wallenstein, who promised immediate succours, and even announced to the Elector the near advance of 12,000 men under Gallas;but at the same time forbade that general, under pain of death, to march.
Meanwhile the Bavarian commandant of Ratisbon, in the hope of speedy assistance, made the best preparations for defence, armed the Roman Catholic peasants, disarmed and carefully watched the Protestant citizens, lest they should attempt any hostile design against the garrison. But as no relief arrived, and the enemy's artillery incessantly battered the walls, he consulted his own safety, and that of the garrison, by an honourable capitulation, and abandoned the Bavarian officials and ecclesiastics to the conqueror's mercy.
The possession of Ratisbon, enlarged the projects of the duke, and Bavaria itself now appeared too narrow a field for his bold designs.
He determined to penetrate to the frontiers of Austria, to arm the Protestant peasantry against the Emperor, and restore to them their religious liberty. He had already taken Straubingen, while another Swedish army was advancing successfully along the northern bank of the Danube. At the head of his Swedes, bidding defiance to the severity of the weather, he reached the mouth of the Iser, which he passed in the presence of the Bavarian General Werth, who was encamped on that river.
