After repeated extensions of the armistice which by common consent prevailed, the King of Sweden resumed hostilities in July, 1621; and the war raged with varying success until September, 1629, when another armistice was concluded for six years. The chief result of this exhausting warfare was the stipulation which was agreed to, that liberty of conscience should be granted to Protestants and Catholics, and that the commerce between Poland and Sweden was declared free.
The renown of these wars, two of which had been brought to a triumphant issue, spread far over Europe; and the Protestant princes of Germany became aware that there was a great military captain of their own faith in the Scandinavian North. They were at that time sorely oppressed, the success of the imperial arms, under Tilly and Wallenstein, seeming to threaten the very existence of the Reformed Faith. The Emperor Ferdinand II. was carrying everything with a high hand after the defeat of King Christian IV. of Denmark, who, with more courage than success, had undertaken to champion the Protestant cause. It was in this desperate strait that all eyes turned toward the young King of Sweden. An appeal was sent to him for aid, in the name of their common religion; and Gustavus, after a brief hesitation, accepted the call. He had long watched with deep concern the war of devastation by which Wallenstein and the scarcely less terrible Tilly were seeking to destroy the fruits of the Reformation; and it is said that he had a clear presentiment that sooner or later he would be drawn into the struggle. Leaving his domestic affairs in the hands of his friend, the Chancellor Oxenstiern, he embarked in June, 1630, with a force of but fifteen thousand men, for Germany, and landed on midsummer day on the island of Usedom, on the coast of Pomerania.
The Emperor Ferdinand professed to be much amused when he heard that Gustavus Adolphus had invaded his dominions.
"So we have got another kingling on our hands," he exclaimed mockingly. He was far from foreseeing what trouble he was to have for eighteen years to come, in getting that kingling and his troops off his hands.
Gustavus was the first to step upon the German soil, at the disembarkation; and in the sight of all his army he fell upon his knees and prayed for the blessing of God upon the vast enterprise which had been confided to him. As he arose from his prayer, he seized a spade and began instantly the work upon the intrenchments of the camp.
If his troops were few in number, it is not to be denied that they were excellent in quality. Many were hardened veterans from the king's earlier campaigns; among his recently acquired mercenaries there was a Scotch brigade, from which he drew many of his best officers. We hear much during the following years, of Hepburn, Seaton, Leslie, Mackay, and Monroe, whose names betray their Caledonian origin. You would have supposed now that the Protestant princes, having secured the aid of Gustavus, would have made haste to identify themselves with his cause and to reinforce him with money and troops. But, strange to relate, no sooner had he landed than they began to grow afraid of him and to ask themselves whether they might not after all, be able to make more tolerable terms with the emperor by the sacrifice of their religion, than with this foreign invader, who, if he was victorious, might dictate his own terms. Had they not, in other words, jumped from the frying-pan into the fire?
The two princes who had hitherto been the most prominent champions of Protestantism in Germany (though both half-hearted and pusillanimous shufflers) were Gustavus's brother-in-law, the Elector of Brandenburg, and the Elector of Saxony. They were now doing their best to wriggle out of their obligations, and by a shameful neutrality avert the emperor's displeasure. But they had reckoned without their host if they supposed that Gustavus would lend himself to such a scheme. The reply which he gave to Herr von Wilmerstorff, who had been sent to him by the Elector to urge an armistice, was refreshingly plain, while the argument which accompanied it was completely unanswerable. When nevertheless the Elector continued to resort to shilly-shallying and all sorts of ambiguous tactics, Gustavus lost his patience, marched his army to the gates of Berlin, and compelled him to make his choice of party once, for all. The treaty of alliance was then signed, on the Elector's part reluctantly and with a heavy heart; for these two brothers-in-law were so vastly different, that it was scarcely to be expected that they would be congenial. Gustavus, though he was not without personal ambition, was fired with noble zeal for the Protestant cause, and believed it worthy of any sacrifice, however great; while the Elector was only bent on saving his own precious skin and extricating himself with the least possible damage from the dangerous situation in which he had been caught.
Gustavus Adolphus before the battle of Lutzen.