Ferdinand II., emperor of Germany and king of Hungary and Bohemia, born July 9, 1578, died in Vienna, Feb. 15, 1637. He was the son of Charles, duke of Styria, third son of Ferdinand I. He was a zealous Catholic, and is said to have made a vow at Loretto that he would exterminate Protestantism. His cousin Matthias, emperor of Germany and king of Hungary and Bohemia, abdicated in his favor the crown of the latter country in 1617, and procured his election as king of the Romans and as his successor in Hungary. The states of Bohemia refused to acknowledge Ferdinand, and a powerful Protestant rising was organized, at the head of which was Count Thurn. Shortly after the death of Matthias (March, 1619), Ferdinand was besieged in Vienna, the insurgents threatening to shut him up in a monas-tery, and cause his children to be educated as Protestants. He however remained firm, and being relieved by the timely arrival of loyal troops, repaired to Frankfort and claimed the imperial crown. He received the votes of all the Catholic electors, and was crowned emperor. The states of Bohemia now offered the royal crown to the elector palatine, Frederick V., son-in-law of James I. of England. Hungary united with Bohemia against Ferdinand, and Bethlen Gabor of Transylvania joined his enemies.

This was properly the beginning of the thirty years' war. Ferdinand was supported by Spain, and Frederick was totally defeated at the battle of Prague in 1620, and driven into exile. Ferdinand was now acknowledged as emperor of Germany and king of Bohemia. He abolished the constitutional charter of Bohemia, and undertook most violent measures against the Protestants; but the latter strengthened their league in Germany by placing Christian IV. of Denmark at its head (1625). The imperialists, under Tilly and Wallenstein, were victorious in several campaigns; and the war was temporarily closed in 1629 by the peace of Lubeck. Ferdinand now redoubled the severity of his measures against the Protestants, when he received a formidable check by the intervention of Gustavus Adolphus of Sweden in 1630. The Protestants were upon the whole successful until the death of Gustavus at the battle of Lutzen, Nov. 6, 1632. The victory at Nordlingen in 1634 was the last great success of Ferdinand's army.