Question: Who is William Cavendish, 5Th Duke Of Devonshire's paternal grandfather?

Knowledge 1: William Cavendish, 5th Duke of Devonshire
William Cavendish, 5th Duke of Devonshire, (14 December 1748 – 29 July 1811), was a British nobleman, aristocrat, and politician.He was the eldest son of William Cavendish, 4th Duke of Devonshire, by his wife, the heiress Lady Charlotte Boyle, "suo jure" Baroness Clifford, who brought in considerable money and estates to the Cavendish family.He was invited to join the Cabinet on three occasions, but declined each offer.He was Lord High Treasurer of Ireland and Governor of Cork, and Lord Lieutenant of Derbyshire.The 5th Duke is best known for his first wife Georgiana, Duchess of Devonshire.At the age of about twenty, Devonshire toured Italy with William Fitzherbert which is where they commissioned the pair of portraits by Pompeo Batoni. [SEP] Knowledge 2: William Cavendish, 4th Duke of Devonshire
William Cavendish, 4th Duke of Devonshire, (8 May 1720 – 2 October 1764), styled Lord Cavendish before 1729 and Marquess of Hartington between 1729 and 1755, was a British Whig statesman and nobleman who was briefly nominal Prime Minister of Great Britain.He was the first son of William Cavendish, 3rd Duke of Devonshire and his wife, the former Catherine Hoskins.
Knowledge 1: William Cavendish, 5th Duke of Devonshire
William Cavendish, 5th Duke of Devonshire, (14 December 1748 – 29 July 1811), was a British nobleman, aristocrat, and politician.He was the eldest son of William Cavendish, 4th Duke of Devonshire, by his wife, the heiress Lady Charlotte Boyle, "suo jure" Baroness Clifford, who brought in considerable money and estates to the Cavendish family.He was invited to join the Cabinet on three occasions, but declined each offer.He was Lord High Treasurer of Ireland and Governor of Cork, and Lord Lieutenant of Derbyshire.The 5th Duke is best known for his first wife Georgiana, Duchess of Devonshire.At the age of about twenty, Devonshire toured Italy with William Fitzherbert which is where they commissioned the pair of portraits by Pompeo Batoni. [SEP] Knowledge 2: Blanche Cavendish, Countess of Burlington
Blanche Cavendish, Countess of Burlington(" née" Howard; 11 January 1812 – 27 April 1840) was the wife of William Cavendish, 2nd Earl of Burlington, who would later become the 7th Duke of Devonshire.
Knowledge 1: William Cavendish, 5th Duke of Devonshire
William Cavendish, 5th Duke of Devonshire, (14 December 1748 – 29 July 1811), was a British nobleman, aristocrat, and politician.He was the eldest son of William Cavendish, 4th Duke of Devonshire, by his wife, the heiress Lady Charlotte Boyle, "suo jure" Baroness Clifford, who brought in considerable money and estates to the Cavendish family.He was invited to join the Cabinet on three occasions, but declined each offer.He was Lord High Treasurer of Ireland and Governor of Cork, and Lord Lieutenant of Derbyshire.The 5th Duke is best known for his first wife Georgiana, Duchess of Devonshire.At the age of about twenty, Devonshire toured Italy with William Fitzherbert which is where they commissioned the pair of portraits by Pompeo Batoni. [SEP] Knowledge 2: Georgiana Cavendish, Duchess of Devonshire
Georgiana Cavendish, Duchess of Devonshire(" née" Spencer;; 7 June 1757 – 30 March 1806), was an English socialite, political organizer, style icon, author, and activist.Of noble birth from the Spencer family, married into the Cavendish family, she was the first wife of William Cavendish, 5th Duke of Devonshire, and the mother of the 6th Duke of Devonshire.As the Duchess of Devonshire, she garnered much attention and fame in society during her lifetime.With a pre-eminent position in the peerage of England, the duchess was famous for her charisma, political influence, beauty, unusual marital arrangement, love affairs, socializing, and gambling.She was the great- great- great- grandaunt of Diana, Princess of Wales.Their lives, centuries apart, have been compared in tragedy.

Answer: William Cavendish, 3rd Duke of Devonshire