Cardinal Richelieu had the merit of effecting this truce with Poland. This great statesman, who guided the helm of Europe, while in France he repressed the rage of faction and the insolence of the nobles, pursued steadily, amidst the cares of a stormy administration, his plan of lowering the ascendancy of the House of Austria. But circumstances opposed considerable obstacles to the execution of his designs; and even the greatest minds cannot, with impunity, defy the prejudices of the age. The minister of a Roman Catholic king, and a Cardinal, he was prevented by the purple he bore from joining the enemies of that church in an open attack on a power which had the address to sanctify its ambitious encroachments under the name of religion. The external deference which Richelieu was obliged to pay to the narrow views of his contemporaries limited his exertions to secret negociations, by which he endeavoured to gain the hand of others to accomplish the enlightened projects of his own mind. After a fruitless attempt to prevent the peace between Denmark and the Emperor, he had recourse to Gustavus Adolphus, the hero of his age. No exertion was spared to bring this monarch to a favourable decision, and at the same time to facilitate the execution of it. Charnasse, an unsuspected agent of the Cardinal, proceeded to Polish Prussia, where Gustavus Adolphus was conducting the war against Sigismund, and alternately visited these princes, in order to persuade them to a truce or peace. Gustavus had been long inclined to it, and the French minister succeeded at last in opening the eyes of Sigismund to his true interests, and to the deceitful policy of the Emperor. A truce for six years was agreed on, Gustavus being allowed to retain all his conquests. This treaty gave him also what he had so long desired, the liberty of directing his arms against the Emperor. For this the French ambassador offered him the alliance of his sovereign and considerable subsidies. But Gustavus Adolphus was justly apprehensive lest the acceptance of the assistance should make him dependent upon France, and fetter him in his career of conquest, while an alliance with a Roman Catholic power might excite distrust among the Protestants.