Charles X., Gastavus, born at Nykoping, Nov. 8, 1622, died at Gothenburg, Feb. 13, 1660. He was the son of John Casimir, prince palatine of Deux-Ponts, and of Catharine, daughter of Charles IX. and sister of Gustavus Adolphus of Sweden. He was carefully educated at the university of Upsal, and afterward travelled in Germany, France, and Switzerland. Gustavus Adolphus, falling at the battle of Liitzen (1632), left his kingdom to his in-fant daughter Christina. The Swedes, however, still carried on the thirty years' war in Germany, and Prince Charles in 1642 entered the Swedish army, and served with distinction under Torstenson. In 1648 he was appointed generalissimo of the Swedish forces in Germany. But the war having in that year been ended by the treaty of Westphalia, Charles returned to Sweden, where he was received with great favor, and was declared heir apparent to the crown. He became enamored of his erratic cousin Queen Christina, who however made light of his attachment, and refused to marry him, but in 1654 abdicated in his favor, and Charles was crowned June 16. He found his kingdom in great disorder. Most of the revenue was absorbed by the pension settled upon Christina, and the interval of peace had impaired the military spirit of the nation.
John Casimir, king of Poland, son of that Sigismund who had been set aside in Sweden in favor of Charles IX., made pretensions to the Swedish crown. Charles thereupon invaded Poland, gained several victories, captured Warsaw and Cracow, and in three months made himself master of all Poland, John Casimir taking refuge in Silesia. Frederick William, elector of Brandenburg, had made incursions into ducal Prussia, which gave umbrage to Charles, who marched against him, and compelled him to acknowledge himself a vassal of Sweden. The rapid success of the Swedes alarmed all Europe, and John Casimir, assured of support, renewed the war. In the depth of winter Charles marched again into Poland, gained a great victory over Czarniecki, and then moved upon Dantzic. The Poles rallied, and, aided by the Tartars, recaptured Warsaw, whither Charles and the elector of Brandenburg marched; and in July, 1656, a battle lasting three days was fought near that city, in which the Swedes were finally victorious. Charles rewarded the services of Frederick William by recognizing him as independent sovereign of Prussia. France, England, and Austria grew jealous of Sweden, the czar Alexis made some hostile movements, and Frederick III. of Denmark declared war against her, and invaded the duchy of Bremen. Charles, leaving a small force in Poland, marched into Holstein, sending Wrangel with another corps to Bremen, and the Swedes gained considerable successes in both directions; but a naval battle, lasting two days, was fought with no decisive result.
Charles was now without a single ally. Poland was in full insurrection; Russia, Austria, and Denmark were in arms; Turkey showed signs of hostility; and the elector of Brandenburg declared against Sweden. Charles resolved upon a sudden blow against Denmark, his nearest enemy. In January, 1658, at the head of 20,000 men, he appeared upon the shore of the Little Belt, which was now frozen over. He crossed upon the ice to the island of Funen, where he cut to pieces a Danish force of 4,500, and then advanced to Langland, Laaland, Falster, and finally to Sceland. The Danes were struck with terror at this unexpected invasion, and gladly accepted the terms offered by Charles, giving up some important places on the Belt. Charles also made peace with the Russians, ceding to them several conquests which they had made. In 1659 the king of Denmark began to show signs of hostile purposes, and Charles resolved to anticipate his overt action. He suddenly appeared with his fleet before Copenhagen. A vigorous assault by the Swedes was repulsed, and a blockade was thereupon established; but the Dutch were unwilling that either Sweden or Denmark should have entire control of the northern waters, and the Dutch fleets supplied provisions to the besieged capital.
Charles went back to Sweden to raise fresh subsidies; but while engaged in strengthening his armies and fleets, he died suddenly of fever. - Charles X. was a ruler of great ability and unbounded ambition, lie aspired to the sovereignty of the north of Europe. He purposed to extend the boundaries of Sweden from the gulf of Finland and Bothnia to the North sea; and according to the reports of the French ambassador, he cherished designs still more vast: when he had made himself master of the north, he would, like a second Alaric, descend upon Italy with a great army and navy, and bring Rome again under the power of the Goths. His life has been written by Pufendorf, Be Helms a Carole- Gustavo gestis (2 vols., Nuremberg, 1696); and in Swedish by Lundblad, who also translated the work into French (1825). He was succeeded by his infant son Charles XL (born in 1655, died in 1697).