On 18 October 1919 the ship was decommissioned and transferred back to the USSB (later the United States Maritime Commission (USMC)).

The ship was operated for MoWT by Royal Mail Lines Ltd. and made several Atlantic crossings in convoy.

Iowa was a steel-hulled, cargo steamship, specially fitted for carrying livestock, and built as yard number 349 by Harland & Wolff Ltd at Belfast.

[6] In 1904 White Diamond deployed Iowa to open a new route between Galveston and Liverpool, bringing large cargos of cotton.

[5][7] Furness Withy considered Iowa too large for their services and sold her in 1913 to the Hamburg America Line who renamed her Bohemia, and intended to convert her to an emigrant carrier with a capacity of 1200 passengers in steerage class.

[8] After the outbreak of World War I on 28 July 1914, many German and Austrian ships took refuge in neutral ports, including the United States.

[9][10] After the United States entered World War I in April 1917, due to her German registry, Bohemia was seized by American customs authorities.

[11] The Navy took control of Artemis at Fletcher's Drydock in Hoboken, New Jersey assigning the identification number (ID.

[15] Laid up by 1923, Artemis remained inactive through the 1930s and into World War II, in the hands of the USSB and its successor, the USMC.

[7] Her port of registry was London and she was operated under the management of Royal Mail Lines Ltd.[17] Empire Bittern was a member of a number of convoys during World War II.

[19] On 23 July 1944, as part of Operation Overlord, Empire Bittern was sunk as an additional breakwater ship to reinforce Gooseberry 3 for Mulberry "B" at Gold Beach near Arromanches-les-Bains.

[3] Empire Bittern regained official number 115329 and had the wireless telegraph call sign BCGL.