But of all who declaimed against the treaty of Prague, none were so loud in their clamours as the Swedes, and none had so much reason for their opposition. Invited to Germany by the Germans themselves, the champions of the Protestant Church, and the freedom of the States, which they had defended with so much bloodshed, and with the sacred life of their king, they now saw themselves suddenly and shamefully abandoned, disappointed in all their hopes, without reward and without gratitude driven from the empire for which they had toiled and bled, and exposed to the ridicule of the enemy by the very princes who owed every thing to them. No satisfaction, no indemnification for the expenses which they had incurred, no equivalent for the conquests which they were to leave behind them, was provided by the treaty of Prague. They were to be dismissed poorer than they came, or, if they resisted, to be expelled by the very powers who had invited them. The Elector of Saxony at last spoke of a pecuniary indemnification, and mentioned the small sum of two millions five hundred thousand florins; but the Swedes had already expended considerably more, and this disgraceful equivalent in money was both contrary to their true interests, and injurious to their pride. "The Electors of Bavaria and Saxony," replied Oxenstiern, "have been paid for their services, which, as vassals, they were bound to render the Emperor, with the possession of important provinces; and shall we, who have sacrificed our king for Germany, be dismissed with the miserable sum of 2,500,000 florins?" The disappointment of their expectations was the more severe, because the Swedes had calculated upon being recompensed with the Duchy of Pomerania, the present possessor of which was old and without heirs. But the succession of this territory was confirmed by the treaty of Prague to the Elector of Brandenburg; and all the neighbouring powers declared against allowing the Swedes to obtain a footing within the empire.
Never, in the whole course of the war, had the prospects of the Swedes looked more gloomy, than in the year 1635, immediately after the conclusion of the treaty of Prague. Many of their allies, particularly among the free cities, abandoned them to benefit by the peace; others were compelled to accede to it by the victorious arms of the Emperor. Augsburg, subdued by famine, surrendered under the severest conditions; Wurtzburg and Coburg were lost to the Austrians. The League of Heilbronn was formally dissolved. Nearly the whole of Upper Germany, the chief seat of the Swedish power, was reduced under the Emperor. Saxony, on the strength of the treaty of Prague, demanded the evacuation of Thuringia, Halberstadt, and Magdeburg. Philipsburg, the military depot of France, was surprised by the Austrians, with all the stores it contained; and this severe loss checked the activity of France. To complete the embarrassments of Sweden, the truce with Poland was drawing to a close. To support a war at the same time with Poland and in Germany, was far beyond the power of Sweden; and all that remained was to choose between them. Pride and ambition declared in favour of continuing the German war, at whatever sacrifice on the side of Poland. An army, however, was necessary to command the respect of Poland, and to give weight to Sweden in any negotiations for a truce or a peace.
The mind of Oxenstiern, firm, and inexhaustible in expedients, set itself manfully to meet these calamities, which all combined to overwhelm Sweden; and his shrewd understanding taught him how to turn even misfortunes to his advantage. The defection of so many German cities of the empire deprived him, it is true, of a great part of his former allies, but at the same time it freed him from the necessity of paying any regard to their interests. The more the number of his enemies increased, the more provinces and magazines were opened to his troops. The gross ingratitude of the States, and the haughty contempt with which the Emperor behaved, (who did not even condescend to treat directly with him about a peace,) excited in him the courage of despair, and a noble determination to maintain the struggle to the last. The continuance of war, however unfortunate it might prove, could not render the situation of Sweden worse than it now was; and if Germany was to be evacuated, it was at least better and nobler to do so sword in hand, and to yield to force rather than to fear.
In the extremity in which the Swedes were now placed by the desertion of their allies, they addressed themselves to France, who met them with the greatest encouragement. The interests of the two crowns were closely united, and France would have injured herself by allowing the Swedish power in Germany to decline. The helpless situation of the Swedes, was rather an additional motive with France to cement more closely their alliance, and to take a more active part in the German war. Since the alliance with Sweden, at Beerwald, in 1632, France had maintained the war against the Emperor, by the arms of Gustavus Adolphus, without any open or formal breach, by furnishing subsidies and increasing the number of his enemies. But alarmed at the unexpected rapidity and success of the Swedish arms, France, in anxiety to restore the balance of power, which was disturbed by the preponderance of the Swedes, seemed, for a time, to have lost sight of her original designs. She endeavoured to protect the Roman Catholic princes of the empire against the Swedish conqueror, by the treaties of neutrality, and when this plan failed, she even meditated herself to declare war against him. But no sooner had the death of Gustavus Adolphus, and the desperate situation of the Swedish affairs, dispelled this apprehension, than she returned with fresh zeal to her first design, and readily afforded in this misfortune the aid which in the hour of success she had refused. Freed from the checks which the ambition and vigilance of Gustavus Adolphus placed upon her plans of aggrandizement, France availed herself of the favourable opportunity afforded by the defeat of Nordlingen, to obtain the entire direction of the war, and to prescribe laws to those who sued for her powerful protection. The moment seemed to smile upon her boldest plans, and those which had formerly seemed chimerical, now appeared to be justified by circumstances. She now turned her whole attention to the war in Germany; and, as soon as she had secured her own private ends by a treaty with the Germans, she suddenly entered the political arena as an active and a commanding power. While the other belligerent states had been exhausting themselves in a tedious contest, France had been reserving her strength, and maintained the contest by money alone; but now, when the state of things called for more active measures, she seized the sword, and astonished Europe by the boldness and magnitude of her undertakings. At the same moment, she fitted out two fleets, and sent six different armies into the field, while she subsidized a foreign crown and several of the German princes. Animated by this powerful co-operation, the Swedes and Germans awoke from the consternation, and hoped, sword in hand, to obtain a more honourable peace than that of Prague. Abandoned by their confederates, who had been reconciled to the Emperor, they formed a still closer alliance with France, which increased her support with their growing necessities, at the same time taking a more active, although secret share in the German war, until at last, she threw off the mask altogether, and in her own name made an unequivocal declaration of war against the Emperor.