Lloyd Royal Belge (Great Britain) Ltd built the ship at Whiteinch, Glasgow, launching her on 26 April 1918 as Ypresville.

[1] Ypresville was built for the UK Government's Shipping Controller, a wartime agency that contracted James Gardiner and Company of Liverpool to manage her.

[2] In 1921 Convoy SS Co sold the ship back to British and South American, who returned her to RP Houston's management but kept her name as Willcasino.

[2] On 1 September 1939, the day that the UK and France declared war against Germany, Clan Macwhirter sailed unescorted from Majunga in Madagascar bound for Colombo in Ceylon.

[5] She continued to trade unescorted in the Indian Ocean and South Atlantic until 1 February 1940, when she reached Freetown in Sierra Leone with a cargo of wheat and maize from Rosario and Buenos Aires in Argentina.

[5] She then traded in the Indian Ocean between ports in Ceylon, India and South Africa until she reached Cape Town on 30 July.

On 13 March 1941 she left Freetown with Convoy SL 68, and when it dispersed at sea as planned she continued unescorted to Halifax, Nova Scotia.

[4] On 27 August at 0100 hours German submarine U-156,[2][4] commanded by Werner Hartenstein, torpedoed Clan Macwhirter about 190 miles northwest of Madeira.

[4] The Portuguese Navy responded by sending the aviso NRP Pedro Nunes, which rescued 67 crew members and seven gunners and landed them at Funchal.