After the unsuccessful attempt of the King of Denmark to check the Emperor's progress, Gustavus Adolphus was the only prince in Europe from whom oppressed liberty could look for protection -- the only one who, while he was personally qualified to conduct such an enterprise, had both political motives to recommend and wrongs to justify it. Before the commencement of the war in Lower Saxony, important political interests induced him, as well as the King of Denmark, to offer his services and his army for the defence of Germany; but the offer of the latter had, to his own misfortune, been preferred. Since that time, Wallenstein and the Emperor had adopted measures which must have been equally offensive to him as a man and as a king. Imperial troops had been despatched to the aid of the Polish king, Sigismund, to defend Prussia against the Swedes. When the king complained to Wallenstein of this act of hostility, he received for answer, "The Emperor has more soldiers than he wants for himself, he must help his friends." The Swedish ambassadors had been insolently ordered by Wallenstein to withdraw from the conference at Lubeck; and when, unawed by this command, they were courageous enough to remain, contrary to the law of nations, he had threatened them with violence. Ferdinand had also insulted the Swedish flag, and intercepted the king's despatches to Transylvania. He also threw every obstacle in the way of a peace betwixt Poland and Sweden, supported the pretensions of Sigismund to the Swedish throne, and denied the right of Gustavus to the title of king. Deigning no regard to the repeated remonstrances of Gustavus, he rather aggravated the offence by new grievances, than acceded the required satisfaction. So many personal motives, supported by important considerations, both of policy and religion, and seconded by pressing invitations from Germany, had their full weight with a prince, who was naturally the more jealous of his royal prerogative the more it was questioned, who was flattered by the glory he hoped to gain as Protector of the Oppressed, and passionately loved war as the element of his genius. But, until a truce or peace with Poland should set his hands free, a new and dangerous war was not to be thought of.