The Duchy of Cleves (German: Herzogtum Kleve; Dutch: Hertogdom Kleef) was a state of the Holy Roman Empire which emerged from the medieval Hettergau [de].
It was situated in the northern Rhineland on both sides of the Lower Rhine, around its capital Cleves and the towns of Wesel, Kalkar, Xanten, Emmerich, Rees and Duisburg bordering the lands of the Prince-Bishopric of Münster in the east and the Duchy of Brabant in the west.
In the early 11th century Emperor Henry II entrusted the administration of the Klever Reichswald, a large forested area around the Kaiserpfalz at Nijmegen directly subordinate to the Imperial rule, to local Lower Lorrainian nobles at Geldern and Kleve.
[1] His daughter Anne of Cleves (1515–1557) even became Queen Consort of England for a few months in 1540, as her brother William, duke since 1539, quarreled with Emperor Charles V over the possession of Guelders and sought support from King Henry VIII.
He died without issue in 1609, and the War of the Jülich Succession broke out between the heirs of his two eldest sisters: Maria Eleonora, Duchess of Prussia, and Anna, Countess of Neuburg.
Finally incorporated into Brandenburg-Prussia by the Great Elector Frederick William I of Brandenburg in 1666[4] and part of the Kingdom of Prussia after 1701, Cleves was occupied by French forces in the Seven Years' War (1757–1762).