The Dukes of Devonshire are members of the aristocraticCavendish family in the United Kingdom. They were related to the 17th century Dukes of Newcastle, with whom they shared the family name of Cavendish. Although in modern usage the county of Devon is now rarely called 'Devonshire', the title remained 'Duke of Devonshire'.
The Duke's subsidiary titles are: Marquess of Hartington (created 1694), Earl of Devonshire (1618), Earl of Burlington (1831), Baron Cavendish of Hardwick (1605) and Baron Cavendish of Keighley (1831). The Duke of Devonshire's eldest son may use the courtesy titleMarquess of Hartington. The Marquessate of Hartington, the Earldom of Devonshire and the Barony of Cavendish of Hardwick are in the peerage of England, while the Earldom of Burlington and the Barony of Cavendish of Keighley are in the United Kingdom peerage.
William Cavendish's descendants were Earls of Devonshire at first. The dukedom started when William Cavendish, the 4th Earl of Devonshire, was created the 1st Duke of Devonshire in 1694 (see below).
Despite the title, the family estates center in Derbyshire. It is sometimes speculated that Derbyshire rather than Devonshire was intended on the original letters patent for the earldom, but no hard evidence supports this.
He was created earl of Devonshire in 1618 by James I., and was succeeded by William, 2nd earl (1591-1628), and the latter by his son William (1617-1684), a prominent royalist, and one of the original members of the Royal Society, who married a daughter of the 2nd earl of Salisbury.
William Cavendish, 1St duke of Devonshire (1640-1707), English statesman, eldest son of the earl of Devonshire last mentioned, was born on the 25th of January 1640.
He left Oxford in 1608, and became the private tutor for the eldest son of Lord Cavendish of Hardwick (later known as the Earl of Devonshire).
From 1634 to 1637 Hobbes returned to the continent with the young Earl of Devonshire.
In 1654 Hobbes was surprised by an unauthorized publication of a tract entitled Of Liberty and Necessity, which he had written in response to an attack by the bishop Bramhall on Leviathan.