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In The Duchess, Ralph Fiennes portrayed William Cavendish, the 5th Duke of Devonshire, a pivotal figure during the reign of King George I and Queen Anne. Known for his political ambitions and complex relationship with his wife Georgiana Spencer, the Duchess of Devonshire, Fiennes brought depth and charisma to the role, capturing the essence of a conflicted nobleman torn between personal desires and societal expectations.