Henry Charles Keith Petty-Fitzmaurice, 5th Marquess of Lansdowne, (14 January 1845 – 3 June 1927) was a British statesman who served successively as the fifth Governor General of Canada, Viceroy of India, Secretary of State for War, and Secretary of State for Foreign Affairs. In 1917, during the First World War, he wrote to the press (the "Lansdowne Letter") vainly advocating a compromise peace. He has the distinction of having held senior positions in both Liberal Party and Conservative Party governments.