Though she was completed too late for the war, she was commissioned into the Naval Overseas Transportation Service (NOTS) of the United States Navy as USS West Cobalt (ID-3836) in January 1919.

Just over four months later, the ship was torpedoed and sunk by German submarine U-99 while carrying supplies to the UK in Convoy SC 7 during the Second World War.

[3] Upon completion of West Cobalt in December 1918,[1] a month after the end of fighting in the First World War, she was handed over to the United States Navy for use in the NOTS.

[2] After undergoing sea trials, West Cobalt sailed for San Pedro, California, on 11 January to load a cargo of grain on behalf of the American Relief Administration.

[2] Many details of West Cobalt's post-Navy career remain undiscovered, but mentions in shipping reports in contemporary newspapers offer hints at her activities.

[9] On 15 October of that year, the captain and four other officers of West Cobalt were arrested at New Orleans after 12 US quarts (11 L) of liquor—against the law under Prohibition—were found on board the ship.

[12] In June 1940, the United States Maritime Commission (USMC) granted permission to Lykes to sell West Cobalt and three other ships to the Bank Line of Glasgow for transfer to British registry.

[15] On the night of 15/16 July, West Cobalt dropped astern of the convoy and was last sighted at 01:00 by British merchant ship Loch Don.

[15] Soon transferred to the Ministry of War Transport, the newly renamed ship, now named Empire Miniver, was assigned to Andrew Weir & Co. of London for operation.

[17][18] Though three ships from the convoy were sunk, two were damaged, and a sixth was a total loss,[18] Empire Miniver arrived at Hampton Roads, on 15 September and at Baltimore two days later.