During World War I, Empress of Britain served as an armed merchant cruiser and a troop carrier. She returned to Canadian Pacific in 1919, but after one roundtrip to St. John, N.B., she underwent a major refitting, which included conversion to oil fuel. She returned to Liverpool-Québec service in the fall of 1920, and moved to Southampton-Québec in 1922. After conversion to cabin class accomodations in 1924, she was renamed Montroyal and placed back on the Liverpool-Québec service. In 1927, she was placed on an Antwerp-Southampton-Cherbourg-Québec service and was on that route when she made her final voyage in September 1929. She was scrapped in Norway in 1930.
Sources: Bonsor's North Atlantic Seaway; Haws' Merchant Fleets.