[3] Assigned to the Naval Overseas Transportation Service, Westport got underway from Seattle bound for Arica, Chile.

[3] After taking aboard a shipment of railroad supplies for the United States Army in France, Westport got underway from Baltimore, Maryland on 1 January 1919 for her first transatlantic crossing.

[3] Westport was allocated the United States Official Number 216901 and the Code Letters KMVF.

Her port of registry was changed to London and she was placed under the management of Mungo, Campbell & Co Ltd.[6] Empire Nightingale would appear to have crossed the Atlantic Ocean from the United States independently, as she does not appear as a member of a convoy until 27 June,[7] when she departed Middlesbrough, Yorkshire as a member of Convoy EC 31.

The convoy had departed from Southend, Essex the previous day and arrived at the Clyde on 1 July.

Empire Nightingale departed Baltimore on 10 August for Halifax, Nova Scotia, Canada, arriving five days later.

[10] Empire Nightingale then joined Convoy FS 589, which departed that day and arrived at Southend on 10 September.

[19] She left the convoy at the Cape Cod Canal and sailed to Philadelphia, Pennsylvania, arriving on 29 April.

Empire Nightingale then joined convoy BX 16,[7] which had departed from Boston and arrived at Halifax on 14 May.

[7] She then joined Convoy BB 183, which departed on 7 June and arrived at Milford Haven, Pembrokeshire the next day.

Empire Nightingale then joined Convoy BX 33,[7] which had departed from Boston on 14 August and arrived at Halifax two days later.

Empire Nightingale departed from Botwood on 2 November with Convoy NJ 20, arriving at St. John's two days later.

[7] Empire Nightingale departed Avonmouth on 4 December for Penarth, Glamorgan, arriving later that day.

Empire Nightingale departed Bougie under escort on 3 February for Algiers, arriving two days later.

[7] Empire Nightingale did not sail in Convoy OS 49 km as planned, but instead departed from Swansea on 16 June for Milford Haven, arriving the next day.

Empire Nightingale was in the part of the convoy that formed KMS 17G and arrived at Gibraltar on 29 June.

[39] Carrying a cargo of phosphates, she joined Convoy MKS 20, which departed that day and arrived at Liverpool on 10 August.

Her destination was Ipswich, Suffolk, which was reached on 14 August via convoys WN 456A and FS 1192.

[42] She then joined Convoy EN 285, which departed on 24 September and arrived at Loch Ewe two days later.

[44] Empire Nightingale sailed on to Loch Ewe, and then joined Convoy WN 507.

Empire Nightingale was in the portion of the convoy that formed KMS 40 and arrived at Gibraltar on 7 February.

That port was reached on 18 March via Loch Ewe and convoys WN 557 and FS 1394.

Her cargo consisted of mail and stores and was stated as bound for Taranto, Apulia, Italy.

Empire Nightingale sailed with Convoy MKS 53 G on 29 June, but put back into Gibraltar the next day.

She was carrying a cargo of iron ore bound for Barrow-in-Furness,[58] arriving on 22 July.

Empire Nightingale was in the portion of the convoy that formed KMS 61 and arrived at Gibraltar on 4 September.

She then joined Convoy VN 64A, which departed that day and arrived at Naples, Campania, Italy on 12 September.

Empire Nightingale departed from Barrow-in-Furness on 28 November and sailed to the Belfast Lough, arriving the next day.

Empire Nightingale then joined Convoy SH 198, which sailed that day and arrived at Halifax on 20 January.

[65] She left the convoy at the Cape Cod Canal and arrived at New York on 27 January.