DORSET, EARLS, MARQUESSES AND DUKES OF, English titles one or more of which had been borne by the families of Beaufort, Grey and Sackville. About 1070 Osmund, or Osmer, an alleged son of Henry, count of Sees, by a sister of William the Conqueror, is said to have been created earl of Dorset, but the authority is a very late one and Osmund describes himself simply as bishop (of Salisbury). William de Mohun of Dunster, a parti san of the empress Matilda, appears as earl of Dorset or Somerset, these two shires being in early times united under a single sheriff. In John Beaufort, earl of Somerset (d. 1410), the eldest son of John of Gaunt, duke of Lancaster, and Catherine Swinford, was created marquess of Dorset ; two years later, however, he was reduced to his former rank of earl of Somerset. In 1411 his brother Thomas, afterwards duke of Exeter, was created earl of Dorset, and in 1441 his youngest son, Edmund, obtained the same dignity. Two years later Edmund was created marquess of Dorset and still later duke of Somerset. Edmund's son Henry, duke of Somerset and marquess of Dorset, was attainted during the Wars of the Roses, and was beheaded after the battle of Hexham in May 1464, when the titles became extinct. In 1475 Thomas Grey, 8th Lord Ferrers of Groby (1451-1501), a son of Sir John Grey (d. 1461) and a stepson of King Edward IV., having resigned the earldom of Huntingdon, which he had received in 1471, was created marquess of Dorset (see below). He was succeeded in this title by his son Thomas (1477-1530), and then by his grand son Henry (1510-54), who was created duke of Suffolk in 1551. When in Feb. 2554 Suffolk was beheaded for sharing in the rising of Sir Thomas Wyat, the marquessate of Dorset again became extinct; but in 1604 Thomas Sackville (see the account of the family under SACKVILLE, IST EARL) was created earl of Dorset (see below), and his descendant, the 7th earl, was created duke in 17 2o. In 1843 the titles became extinct.