Archibald Algernon Henry St. Maur, formerly Seymour, 13th Duke of Somerset, etc. (30 December 1810 - 28 Berkeley Square, London, Oct 1891) was the son of Edward St. Maur, 11th Duke of Somerset and Lady Charlotte Douglas-Hamilton. He was also a baronet. His motto, French: Foy Pour Devoir, "Faith for Duty", has been adopted by HMS Somerset (IV) by permission.
He was baptized on 17 June 1811 at St. George's, Hanover Square, London,[1] and succeeded his brother Edward Seymour, 12th Duke of Somerset, in 1885. In his younger years, he had served as a captain in the Royal Horse Guards.[2] He spent much of his life at Burton Hall, in The Wolds, managing the estate.[3] He served as High Sheriff of Leicestershire for 1844.
Archibald died at his London home in Berkeley Square,[4] unmarried and childless. He was buried in the churchyard at Maiden Bradley, Wiltshire on 16 January 1891.[5] A memorial in the style of a grave was erected in the churchyard at Berry Pomeroy, Devon. His titles passed to his brother, Algernon St. Maur.