Sackville is the son of Charles Sackville, 6th Earl of Dorset and 1st Earl of Middlesex, and the former Lady Mary Compton, younger daughter of James Compton, 3rd Earl of Northampton. Styled Lord Buckhurst from birth, he succeeds his father as 7th Earl of Dorset and 2nd Earl of Middlesex in 1706, and is created Duke of Dorset in 1720.
Perhaps because he had been on a previous diplomatic mission to Hanover, Sackville is chosen to inform George I of his accession to the Crown in August 1714. George I initially favours him and numerous offices and honours are given to him: Privy Councillor, Knight of the Garter, Groom of the Stool, Lord Steward, Governor of Dover Castle and Lord Warden of the Cinque Ports. At George I’s coronation he carries the sceptre. At the coronation of George II he is Lord High Steward and carries St. Edward’s Crown. He quarrels with the King in 1717 and is told his services are no longer required, but he is made a Duke three years later.
Sackville serves twice as Lord Lieutenant of Ireland, from 1731 to 1737 and again from 1751 to 1755. In 1739, at the foundation of the Foundling Hospital, he is one of that charity’s original governors. His first term as Lord Lieutenant is uneventful. His second takes place at a time of acute political tension between the two main factions in the Irish Government, one led by Henry Boyle, the Speaker of the Irish House of Commons, the other by George Stone, the Anglican Archbishop of Armagh. Sackville, now heavily influenced by his son George Sackville, makes the mistake of openly backing the Archbishop. He is unable to oust Boyle from power, and is accused of being the Archbishop’s tool. He becomes extremely unpopular, leading to his eventual recall.
Sackville’s last years are uneventful, apart from a riot in 1757 caused by the passage of the Militia Act to raise an army for the Seven Years’ War, in which he narrowly escapes injury. He dies at Knole, a country house in west Kent, on October 9, 1765 and is buried at Withyham in East Sussex.
(Pictured: Oil on canvas Portrait of Lionel Sackville, 1st Duke of Dorset (1688-1765) by Godfrey Kneller (1646-1723), 1719, currently displayed at Commonwealth Secretariat, Marlborough House, London)