Mansfeld, COUNTS OF, an old German noble family (founded circa 1060), whose ancestral castle stood at the east end of the Harz Mountains, 14 miles NW. of Halle. Two members of the family have acquired historical reputation. COUNT PETER ERNEST I., afterwards elevated to the rank of a prince, was born on 15th July 1517. Having taken part in Charles V.'s expedition against Tunis, and distinguished himself afterwards at the siege of Landrecies, he was made by the emperor governor of the duchy of Luxemburg. But in 1552, whilst raiding in Champagne, he was taken prisoner by the French, and not ransomed until 1557. He fought against them again at St Quentin. On the outbreak of the revolt in the Low Countries he made a name as one of the cleverest generals in the Spanish service. Having been sent by Alva to the assistance of the French king against the Protestants, he covered himself with glory at Montcontour (1569). He subsequently took part in many sieges and military operations in the Netherlands, and acted for a while as governor of the Spanish Low Countries. In 1597 he retired to Luxemburg, where he had gathered a valuable collection of antique art, and died there on 22d May 1604.
His illegitimate son, PETER ERNEST II., usually called Count Ernest von Mansfeld, was one of the most prominent military leaders during the Thirty Years' War (q.v.). Born at Luxemburg in 1580, he served his apprenticeship to war in the Austrian service in Hungary and in the Juliers dispute. As part of his reward he was promised his father's possessions; but when it came to the pinch, they were refused to him. This converted Mansfeld into an implacable enemy, and he went over to the side of the Protestant princes. He assisted the Duke of Savoy against the Spaniards (1613-17), and in 1618 was despatched to Bohemia, to aid the Count-Palatine Frederick, and captured Pilsen and other strong-holds. But the disaster of the Weissenberg compelled him to retreat to the Palatinate, from which he carried on for nearly two years a semi-predatory war on the imperialists, defeating Tilly at Wiesloch (April 1622). When Frederick abandoned the struggle, Mansfeld, with his chosen ally Christian of Brunswick, a swashbuckling adventurer like himself, fought his way through the
Spanish-Austrian forces to take service for the United Netherlands, beating Cordova at Fleurus (29th August). At the bidding of his new masters Mansfeld chastised the Count of East Friesland, and then, dismissing his army, retired into private life at The Hague. But in 1624 he resumed active work again at the solicitation of Richelieu. With an army of 12,000 men, raised mostly in England, he renewed the struggle on the Lower Elbe, till on 25th April 1626 he was crushingly defeated by Wallenstein at the bridge at Dessau. Once more raising a force of 12,000 in Brandenburg, with these and 5000 Danes he marched by way of Silesia to join hands in Moravia and Hungary with Bethlen Gabor of Transylvania. But the French and English subsidies failing, on which he relied for pay for his men, he was making his way to Venice with a few officers to raise fresh moneys when he fell sick and died, standing, clad in full panoply and supported by two attendants, at Racovitz, near Serajevó in Bosnia, on 29th November 1626. Count Ernest, a soldier of fortune, was the idol of his lawless soldiery, whom he frequently allowed to plunder and raid to their heart's content, so that they were a terror to friends as well as foes.