Wallenstein grew too powerful for the emperor he saved, and was killed for it
A poor Protestant noble from Bohemia, Albrecht von Wallenstein converted, married money and raised an army of 50,000 men for the Catholic emperor. He became one of the richest men in the Holy Roman Empire. Then he tried to negotiate peace on his own, and his master approved his assassination.
He was born on 24 September 1583 at Heřmanice in Bohemia, into an impoverished Protestant branch of the old Waldstein family that owned a castle and seven villages. His parents followed Lutheran and Hussite traditions, raised him speaking Czech and German, and died while he was a boy. As a student at Altdorf near Nuremberg he brawled, fought duels, landed in the town jail and beat a servant so badly he had to pay compensation. Later travels through France and Italy, with study at Bologna and Padua, left him fluent in four languages. Legend says he kept swearing in Czech.
After two years fighting the Ottomans in Hungary, he converted to Catholicism in 1606, perhaps influenced by the Jesuits at Olomouc and by Habsburg rules that kept Protestants out of high office, though no source settles his motives. In 1609 he married a rich widow, whose death in 1614 left him her estates, and in 1617 he began raising troops for the emperor as a military entrepreneur.
The Thirty Years' War made him. He fought against the Bohemian rebels of 1618 and was rewarded with confiscated lands after White Mountain in 1620. In 1625 he raised his great army, crushed the Protestants at Dessau Bridge the following year and carved out the Duchy of Friedland for himself. By April 1628 he was supreme commander on land and Admiral of the Baltic.
His ambition alarmed Ferdinand II, who dismissed him in 1630. Protestant victories forced the emperor to bring him back, and Wallenstein beat Gustavus Adolphus of Sweden at Alte Veste; the Swedish king later died at Lützen. Convinced the war could drag on for decades, Wallenstein arranged truces in summer 1633 to open peace talks, and even considered joining the Protestants. Enemies called it treason. On 25 February 1634 he was murdered at Eger with Ferdinand's approval. Historians now count him among the great commanders of the early modern age.
Source: Albrecht von Wallenstein