Emperor of Germany (1619-37), grandson of the preceding and son of Charles, younger brother of Maximilian II., born at Gratz; his detestation of the Protestants, early instilled into him by his mother and the Jesuits, under whom he was educated, was the ruling passion of his life, and involved the empire in constant warfare during his reign; an attempt on the part of Bohemia, restless under religious and political grievances, to break away from his rule, brought about the Thirty Years' War; by ruthless persecutions he re-established Catholicism in Bohemia, and reduced the country to subjection; but the war spread into Hungary and Germany, where Ferdinand was opposed by a confederacy of the Protestant States of Lower Saxony and Denmark, and in which the Protestant cause was in the end successfully sustained by the Swedish hero, Gustavus Adolphus, who had opposed to him the imperial generals Tilly and Wallenstein; his reign is regarded as one of disaster, bloodshed, and desolation to his empire, and his connivance at the assassination of Wallenstein will be forever remembered to his discredit (1578-1637).