Is it ensure, insure, or assure?
name given to a man of great hardihood or bravery, c.1300, first applied to Edmund II, king of England (d.1016), later also to Oliver Cromwell and his troops. Old Ironsides as a nickname of U.S.S. "Constitution" dates from that ship's defeat of H.M.S. "Guerriere" on Aug. 19, 1812, in the War of 1812.