[1] Assigned to the Naval Overseas Transportation Service, Western Chief departed Portland on 12 July 1918 carrying 7,170 tons of flour and proceeded via the Panama Canal to New York City, making port there on 15 August 1918.

After unloading her flour, she loaded 20 trucks and moved to Norfolk, Virginia, from which she got underway on 22 August 1918 as part of a convoy bound for France.

She called at the Hook of Holland; Dartmouth, England; Danzig, Germany; and Copenhagen, Denmark, before she returned to the United States, making port at Baltimore, Maryland, on 25 June 1919.

Early in World War II, the British government purchased Western Chief to help to alleviate the shipping shortage the United Kingdom faced due to losses to Axis submarines.

In British service, Western Chief was on a voyage, under Captain Eric Alexander Brown, Master with Hogarth's shipowners, as a part of Convoy SC 24 when she was sunk at 13:07 on 14 March 1941 by the Italian submarine Emo in the North Atlantic Ocean 250 nautical miles (463 km) south of Iceland at 58°52′N 21°13′W / 58.867°N 21.217°W / 58.867; -21.217.