William Cavendish

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 who was briefly nominal Prime Minister of Great Britain. He was the first son of William Cavendish, 3rd Duke of Devonshire and Catherine Hoskins.

Devonshire was given the Garter and appointed First Lord of the Treasury (most historians consider him Prime Minister during this service) in November 1756, and he served as First Lord until May 1757 in an administration effectively run by William Pitt. Devonshire's administration secured increased money for the war, troops were sent to America and a Militia Act was passed.

The administration was eventually brought down for a variety of reasons including the opposition of George II and the alleged mishandling of the trial and execution of Admiral John Byng. It was replaced by the Second Newcastle Ministry headed by the Duke of Newcastle and including Pitt, Henry Fox and the Duke of Bedford. This government steered Britain through most of the Seven Years' War leading the country to ultimate victory.