Under these advantages, and reinforced by 14,000 fresh troops from Sweden and Livonia. Banner opened, with the most favourable prospects, the campaign of 1638. The Imperialists who were in possession of Upper Pomerania and Mecklenburg, either abandoned their positions, or deserted in crowds to the Swedes, to avoid the horrors of famine, the most formidable enemy in this exhausted country. The whole country betwixt the Elbe and the Oder was so desolated by the past marchings and quarterings of the troops, that, in order to support his army on its march into Saxony and Bohemia, Banner was obliged to take a circuitous route from Lower Pomerania into Lower Saxony, and then into the Electorate of Saxony through the territory of Halberstadt. The impatience of the Lower Saxon States to get rid of such troublesome guests, procured him so plentiful a supply of provisions, that he was provided with bread in Magdeburg itself, where famine had even overcome the natural antipathy of men to human flesh. His approach spread consternation among the Saxons; but his views were directed not against this exhausted country, but against the hereditary dominions of the Emperor. The victories of Bernard encouraged him, while the prosperity of the Austrian provinces excited his hopes of booty.
After defeating the Imperial General Salis, at Elsterberg, totally routing the Saxon army at Chemnitz, and taking Pirna, he penetrated with irresistible impetuosity into Bohemia, crossed the Elbe, threatened Prague, took Brandeis and Leutmeritz, defeated General Hofkirchen with ten regiments, and spread terror and devastation through that defenceless kingdom. Booty was his sole object, and whatever he could not carry off he destroyed. In order to remove more of the corn, the ears were cut from the stalks, and the latter burnt.
Above a thousand castles, hamlets, and villages were laid in ashes;sometimes more than a hundred were seen burning in one night.
From Bohemia he crossed into Silesia, and it was his intention to carry his ravages even into Moravia and Austria. But to prevent this, Count Hatzfeld was summoned from Westphalia, and Piccolomini from the Netherlands, to hasten with all speed to this quarter.
The Archduke Leopold, brother to the Emperor, assumed the command, in order to repair the errors of his predecessor Gallas, and to raise the army from the low ebb to which it had fallen.
The result justified the change, and the campaign of 1640 appeared to take a most unfortunate turn for the Swedes. They were successively driven out of all their posts in Bohemia, and anxious only to secure their plunder, they precipitately crossed the heights of Meissen. But being followed into Saxony by the pursuing enemy, and defeated at Plauen, they were obliged to take refuge in Thuringia. Made masters of the field in a single summer, they were as rapidly dispossessed; but only to acquire it a second time, and to hurry from one extreme to another. The army of Banner, weakened and on the brink of destruction in its camp at Erfurt, suddenly recovered itself. The Duke of Lunenburg abandoned the treaty of Prague, and joined Banner with the very troops which, the year before, had fought against him. Hesse Cassel sent reinforcements, and the Duke of Longueville came to his support with the army of the late Duke Bernard. Once more numerically superior to the Imperialists, Banner offered them battle near Saalfeld; but their leader, Piccolomini, prudently declined an engagement, having chosen too strong a position to be forced. When the Bavarians at length separated from the Imperialists, and marched towards Franconia, Banner attempted an attack upon this divided corps, but the attempt was frustrated by the skill of the Bavarian General Von Mercy, and the near approach of the main body of the Imperialists.
Both armies now moved into the exhausted territory of Hesse, where they formed intrenched camps near each other, till at last famine and the severity of the winter compelled them both to retire.
Piccolomini chose the fertile banks of the Weser for his winter quarters;but being outflanked by Banner, he was obliged to give way to the Swedes, and to impose on the Franconian sees the burden of maintaining his army.
At this period, a diet was held in Ratisbon, where the complaints of the States were to be heard, measures taken for securing the repose of the Empire, and the question of peace or war finally settled.
The presence of the Emperor, the majority of the Roman Catholic voices in the Electoral College, the great number of bishops, and the withdrawal of several of the Protestant votes, gave the Emperor a complete command of the deliberations of the assembly, and rendered this diet any thing but a fair representative of the opinions of the German Empire. The Protestants, with reason, considered it as a mere combination of Austria and its creatures against their party;and it seemed to them a laudable effort to interrupt its deliberations, and to dissolve the diet itself.
Banner undertook this bold enterprise. His military reputation had suffered by his last retreat from Bohemia, and it stood in need of some great exploit to restore its former lustre. Without communicating his designs to any one, in the depth of the winter of 1641, as soon as the roads and rivers were frozen, he broke up from his quarters in Lunenburg. Accompanied by Marshal Guebriant, who commanded the armies of France and Weimar, he took the route towards the Danube, through Thuringia and Vogtland, and appeared before Ratisbon, ere the Diet could be apprised of his approach.
The consternation of the assembly was indescribable; and, in the first alarm, the deputies prepared for flight. The Emperor alone declared that he would not leave the town, and encouraged the rest by his example.
