The line of
Hesse-Kassel (or 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; this formed the
Landgraviate of Hesse-Kassel. Additions were made to it by inheritance from his brother's possessions. His son,
Maurice the Learned (1572–1632) was Landgrave of Hesse-Kassel from 1592 until 1627. Maurice converted to Calvinism 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 1627 in favour of his son
William V (1602–1637). His younger sons received apanages, which created several cadet lines of the house (Hesse-Rotenburg,
Hesse-Eschwege and
Hesse-Rheinfels), of which, with amalgamation, that of Hesse-Rheinfels-Rotenburg survived till 1834. In 1627, Ernest (1623–1693), a younger son of Maurice, received
Rheinfels and lower
Katzenelnbogen as his inheritance. Some years later, on the deaths of two of his brothers,
Frederick, Landgrave of Hesse-Eschwege (1617–1655) and
Herman IV, Landgrave of Hesse-Rotenburg (1607–1658), he added
Eschwege,
Rotenburg,
Wanfried and other districts to his possessions. Ernest, who was a convert to the Roman Catholic Church, was a great traveller and a voluminous writer. About 1700 his two sons,
William (d. 1725) and
Charles (or Karl) (d. 1711), divided their territories, and founded the families of Hesse-Rotenburg and
Hesse-Wanfried. The latter family died out in 1755, when William's grandson,
Constantine (d. 1778), reunited the lands except Rheinfels, which had been acquired by Hesse-Kassel in 1735, and ruled them as Landgrave of Hesse-Rotenburg. At the
peace of Lunéville in 1801, the part of the landgraviate on the left bank of the Rhine was surrendered to France and, in 1815, other parts were ceded to Prussia, the landgrave
Victor Amadeus being compensated by the abbey of Corvey and the Silesian
Duchy of Ratibor. Victor was the last male member of his family, so, with the consent of Prussia, he bequeathed his
allodial estates to his nephews the princes Victor and
Chlodwig of
Hohenlohe-Waldenburg-Schillingsfürst. When the landgrave died on 12 November 1834 the remaining parts of Hesse-Rotenburg were united with Hesse-Kassel according to the arrangement of 1627. Hesse-Rotenburg was never completely independent of Hesse-Kassel. The most important member of the family was probably
Polyxena,
Queen consort of Sardinia as wife of
Charles Emmanuel III of Sardinia. Perhaps the most famous member of this family was
Charles Constantine (1752–1821), a younger son of Landgrave
Constantine, who took part in the French Revolution under the name
Citoyen Hesse. ==List of landgraves==