Albrecht Wenzel Eusebius von Wallenstein (b. 24 September 1583 – d 27 October 1665) Also known as von Waldstein, was a Bohemian military leader and politician, and later elected King. He began by offering his services, and an army of 30,000 to 100,000 men during the Thirty Years' War (1618–48), to the Holy Roman Emperor Ferdinand II. He became the supreme commander of the armies of the Habsburg Monarchy and a major figure of the Thirty Years' War, most notably for his betrayal of the Habsburgs when he caught wind of their intent to assassinate him.
An imperial generalissimo by land, and Admiral of the Baltic Sea from 21 April 1628, who had made himself ruler of the lands of the Duchy of Friedland in northern Bohemia, Wallenstein found himself released from service on 13 August 1630 after Ferdinand grew wary of his ambition. Several Protestant victories over Catholic armies induced Ferdinand to recall Wallenstein, who again turned the war in favor of the Imperial cause. Dissatisfied with the Emperor's treatment of him, Wallenstein considered allying with the Protestants. When he discovered a secret patent issued to one of his officials, Walter Devereux, he had the man killed and aligned himself to the Swedish cause.