The most powerful of these kings was Christian I., who founded the dynasty of Oldenburgh, and who united under his sway the kingdoms of Denmark, Sweden, and Norway. He reigned from 1448 to 1481; and in his family the crown of Sweden remained until the revolution effected by Gustavus Vasa, in 1525, and by which revolution Sweden was made independent of Denmark. [Sidenote: Gustavus Vasa.] Gustavus Vasa was a nobleman descended from the ancient kings of Sweden, and who, from the oppression to which his country was subjected by Christian and the Archbishop of Upsal, was forced to seek refuge amid the forests of Dalecarlia. When Stockholm was pillaged and her noblest citizens massacred by the cruel tyrant of the country, Gustavus headed an insurrection, defeated the king's forces, and was made king himself by the Diet. He, perceiving that the Catholic clergy were opposed to the liberties and the great interests of his country, seized their fortresses and lands, became a convert to the doctrine of the reformers, and introduced Lutheranism into the kingdom, which has ever since been the established religion of Sweden. He was despotic in his government, but ruled for the good of his subjects, and was distinguished for many noble qualities. The celebrated Gustavus Adolphus was his descendant, and was more absolute and powerful than even Gustavus Vasa. But he is chiefly memorable as the great hero of the Thirty Years' War, and as the greatest general of his age. Under his sway, Sweden was the most powerful of the northern kingdoms. He was succeeded by his daughter Christina, a woman of most extraordinary qualities; a woman of genius, of taste, and of culture; a woman who, at twenty-seven, became wearied of the world, and of the enjoyment of unlimited power, and who changed her religion, retired from her country, and abdicated her throne, that she might, unmolested, enjoy the elegant pleasures of Rome, and be solaced by the literature, religion, and art of that splendid capital. It was in the society of men of genius that she spent most of her time, and was the life of the most intellectual circle which then existed in Europe. She was succeeded by her cousin, who was elected King of Sweden, by the title of _Charles Gustavus X._, and he was succeeded by Charles XI., the father of Charles XII. Charles XII. was fifteen years of age when he came to the throne, in the year 1697, and found his country strong in resources, and his army the best disciplined in Europe. His territories were one third larger than those of France when ruled by Louis XIV., though not so thickly populated. [Sidenote: Early Days of Charles XII.] The young monarch, at first, gave but few indications of the remarkable qualities which afterwards distinguished him. He was idle, dissipated, haughty, and luxurious. When he came to the council chamber, he was absent and indifferent, and generally sat with both legs thrown across the table.