Served as quartermaster on board the U.S.S. Oneida in the engagement at Mobile Bay, 5 August 1864. Acting as captain of the after 11-inch gun, and wounded in several places, Sheridan remained at his gun until the firing had ceased and then took the place of the signal quartermaster who had been injured by a fall. Recommended for his gallantry and intelligence, Sheridan served courageously throughout this battle which resulted in the capture of the rebel ram Tennessee and the damaging of Fort Morgan.