Gustavus II., or Gustavus Adolphus (1594-1632), became King of Sweden in 1611, on the death of his father, Charles IX., the son of Gustavus Vasa. He had received the best education which the times could give, and early gave proof of the restless energy, the stern force of character, and the firm adhesion to the Lutheran faith which distinguished his character in after life. At the time of his accession the country was overrun by Danish troops, but after a struggle of two years he secured a peace by which Sweden retained Gottenborg, Calmar, and Oeland. He next turned his attention to an enterprise which occupied him for the rest of his life - the establishment of Swedish sovereignty in the Baltic Sea. With this object he engaged in a war with Russia, and in 1617 he could boast that Russian vessels had been driven from the Baltic coasts. He next became involved in a war with his nephew Sigismund of Poland, the legal heir to the Swedish throne, who had been excluded on account of his adhesion to the Roman Catholic religion. This contest brought him into connection with Germany, for the Emperor Ferdinand was Sigismund's brother-in-law, and would be likely to render him aid. In 1620 Gustavus espoused the sister of George William, Elector of Brandenburg. The extension of Swedish power, the support of the German princes in their efforts to maintain their independence, and the furtherance of German Protestantism gradually formed themselves in his mind as parts of one great scheme. In 1628 he sent relief to Stralsund during its siege by Wallenstein. A treaty with Poland in 1629, which placed Elbing, Braunsberg, and Memel in his hands, left him free to take a more active part in Germat affairs. In 1630 he landed in Pomerania, leaving Sweden under the government of his chancellor Oxenstjerna. The aged Boguslav, Duke of Pomerania, was persuaded to promise him support and to make him his heir, and by the treaty of Barwalde (January, 1631) a large French subsidy was secured for a period of five years ; but the princes of North Germany were loath to enter on a course which would openly sever their connection with the empire. Fear alone induced the Elector of Brandenburg to admit his troops into Spandau, and John George, Elector of Saxony, joined him too late for him to avert the fall of Magdeburg. On September 17 Tilly, the Imperial general, was defeated by a joint army of Swedes and Saxons at Breitenfeld near Leipzig. After rejecting the overtures of Wallenstein, Gustavus determined on marching to the Rhine provinces, as a centre of Protestant influence, where he might form the Coi'pus Evanc/elicorum, which was to take the place of the Empire. After establishing his power in the Palatinate and wintering at Mentz, he advanced in the following spring through Franconia into Bavaria. Tilly was defeated and mortally wounded at the passage of the Lech, and Gustavus entered Munich in triumph; but in the meantime Wallenstein had been recalled, and, after failing to storm his entrenchments at Nuremberg (September, 1632), Gustavus was forced to follow him into Saxony. He was overtaken and defeated at Liitzen, but Gustavus himself, cut off by his rash impetuosity from the main body of his troops, lost his life in the battle. The fame of Gustavus is based on his career as the champion of European Protestantism, but he also introduced many domestic reforms which endeared him to his own countrymen.