HESSE-CASSEL (in German _Kurhessen_, i.e. Electoral Hesse), now the government district of Cassel in the Prussian province of Hesse-Nassau. It was till 1866 a landgraviate and electorate of Germany, consisting of several detached masses of territory, to the N.E. of Frankfort-on-the-Main. It contained a superficial area of 3699 sq. m., and its population in 1864 was 745,063. _History._--The line of Hesse-Cassel was founded by William IV., surnamed the Wise, eldest son of Philip the Magnanimous. On his father's death in 1567 he received one half of Hesse, with Cassel as his capital; and this formed the landgraviate of Hesse-Cassel. Additions were made to it by inheritance from his brother's possessions. His son, Maurice the Learned (1592-1627), turned Protestant in 1605, became involved later in the Thirty Years' War, and, after being forced to cede some of his territories to the Darmstadt line, abdicated in favour of his son William V. (1627-1637), his younger sons receiving apanages which created several cadet lines of the house, of which that of Hesse-Rheinfels-Rotenburg survived till 1834. On the death of William V., whose territories had been conquered by the Imperialists, his widow Amalie Elizabeth, as regent for her son William VI. (1637-1663), reconquered the country and, with the aid of the French and Swedes, held it, together with part of Westphalia. At the peace of Westphalia (1648), accordingly, Hesse-Cassel was augmented by the larger part of the countship of Schaumburg and by the abbey of Hersfeld, secularized as a principality of the Empire. The Landgravine Amalie Elizabeth introduced the rule of primogeniture. William VI., who came of age in 1650, was an enlightened patron of learning and the arts. He was succeeded by his son William VII., an infant, who died in 1670, and was succeeded by his brother Charles (1670-1730). Charles's chief claim to remembrance is that he was the first ruler to adopt the system of hiring his soldiers out to foreign powers as mercenaries, as a means of improving the national finances. Frederick I., the next landgrave (1730-1751), had become by marriage king of Sweden, and on his death was succeeded in the landgraviate by his brother William VIII. (1751-1760), who fought as an ally of England during the Seven Years' War. From his successor Frederick II. (1760-1785), who had become a Roman Catholic, 22,000 Hessian troops were hired by England for about L3,191,000, to assist in the war against the North American colonies. This action, often bitterly criticized, has of late years found apologists (cf. v. Werthern, _Die hessischen Hilfstruppen im nordamerikanischen Unabhangigkeitskriege_, Cassel, 1895). It is argued that the troops were in any case mercenaries, and that the practice was quite common. Whatever opinion may be held as to this, it is certain that Frederick spent the money well: he did much for the development of the economic and intellectual improvement of the country.