 Trenchard commanded the screw sloop , flagship of the South Atlantic Squadron, in 1869-71, then, with the rank of commodore, served for three years as an Inspector of the Third Lighthouse District.On August 10, 1875, Trenchard attained the rank of rear admiral and commanded the North Atlantic Squadron, with the as his flagship.In 1876, during the controversy over the Hayes-Tilden presidential election Trenchard was in command of a Naval Brigade that was stationed in Washington D.C., to preserve order.