Among the means of which Gustavus Vasa, the founder of the Swedish monarchy, availed himself to strengthen his new edifice, the Reformation had been one of the principal. A fundamental law of the kingdom excluded the adherents of popery from all offices of the state, and prohibited every future sovereign of Sweden from altering the religious constitution of the kingdom. But the second son and second successor of Gustavus had relapsed into popery, and his son Sigismund, also king of Poland, had been guilty of measures which menaced both the constitution and the established church. Headed by Charles, Duke of Sudermania, the third son of Gustavus, the Estates made a courageous resistance, which terminated, at last, in an open civil war between the uncle and nephew, and between the King and the people. Duke Charles, administrator of the kingdom during the absence of the king, had availed himself of Sigismund's long residence in Poland, and the just displeasure of the states, to ingratiate himself with the nation, and gradually to prepare his way to the throne. His views were not a little forwarded by Sigismund's imprudence. A general Diet ventured to abolish, in favour of the Protector, the rule of primogeniture which Gustavus had established in the succession, and placed the Duke of Sudermania on the throne, from which Sigismund, with his whole posterity, were solemnly excluded. The son of the new king (who reigned under the name of Charles IX.) was Gustavus Adolphus, whom, as the son of a usurper, the adherents of Sigismund refused to recognize. But if the obligations between monarchy and subjects are reciprocal, and states are not to be transmitted, like a lifeless heirloom, from hand to hand, a nation acting with unanimity must have the power of renouncing their allegiance to a sovereign who has violated his obligations to them, and of filling his place by a worthier object. Gustavus Adolphus had not completed his seventeenth year, when the Swedish throne became vacant by the death of his father. But the early maturity of his genius enabled the Estates to abridge in his favour the legal period of minority. With a glorious conquest over himself he commenced a reign which was to have victory for its constant attendant, a career which was to begin and end in success. The young Countess of Brahe, the daughter of a subject, had gained his early affections, and he had resolved to share with her the Swedish throne. But, constrained by time and circumstances, he made his attachment yield to the higher duties of a king, and heroism again took exclusive possession of a heart which was not destined by nature to confine itself within the limits of quiet domestic happiness.