High Quality Content by WIKIPEDIA articles! The title Duke of Beaufort in the Peerage of England was created by Charles II in 1682 for Henry Somerset, 3rd Marquess of Worcester, a descendant of Charles Somerset, 1st Earl of Worcester, illegitimate son of Henry Beaufort, 3rd Duke of Somerset, a Lancastrian leader in the Wars of the Roses. The name Beaufort refers to a castle in Champagne, France (now Montmorency-Beaufort). It is the only current Dukedom to take its name from a place outside the British Isles. They are descendants in the male line from the House of Plantagenet through John of Gaunt and Edward III. Beaufort Castle was a possession of John of Gaunt, and the surname Beaufort was given to Gaunt's four illegitimate (later legitimated) children by his mistress and third wife, Katherine Swynford. The Duke of Beaufort holds two subsidiary titles: Marquess of Worcester (created 1642) and Earl of Worcester (1514). The title Marquess of Worcester is used as a courtesy title by the Duke's eldest son and heir. The title Earl of Glamorgan is used by the eldest son of the heir-apparent to the Dukedom. The Earl of Glamorgan's eldest son is known as Viscount Grosmont.