The Poles made a pretence of setting their own king, Sigismund, upon the throne of Sweden; and for eighteen years Gustavus Adolphus had bravely defended his rights, and protected and extended his kingdom up to the truce of Altenmarket, concluded in 1629 through the intervention of Richelieu, who had need of the young King of Sweden in order to oppose the Emperor Ferdinand and the dangerous power of the house of Austria.

Summoned to Germany by the Protestant princes who were being oppressed and despoiled, and assured of assistance and subsidies from the King of France, Gustavus Adolphus had, no doubt, ideas of a glorious destiny, which have been flippantly taxed with egotistical ambition.

Perhaps, in the noble joy of victory, when he "was marching on without fighting," seeing provinces submit, one after another, without his being hardly at the pains to draw his sword, might he have sometimes dreamed of a Protestant empire and the imperial crown upon his head; but, assuredly, such was not the aim of his enterprise and of his life.

"I must in the end make a sacrifice of myself," he had said on bidding farewell to the Estates of Sweden; and it was to the cause of Protestantism in Europe that he made this sacrifice.

Sincerely religious in heart, Gustavus Adolphus was not ignorant that his principal political strength was in the hands of the Protestant princes; and he put at their service the incomparable splendor of his military genius.