The ship served primarily as an ore carrier on runs between ports in Spain and her home country for seven years before being sold to Irish owners, the Limerick Steamship Co, with whom she operated for the remainder of her career.

Luimneach departed Huelva on 2 September 1940 under the command of Eric Septimus Jones, transporting 1,250 tons of pyrites back to Drogheda in Ireland.

Two days out of port, she was stopped in international waters by the German U-boat U-46, under the command of Engelbert Endrass, with two shots across her bow[3] about 170 miles west-southwest of Ushant.

[4] Some confusion existed between parties in this incident, with the merchant crew believing the submarine was Italian while Endrass was unsure of the nationality of the ship he'd stopped.

Endrass also reported in his log that the merchant crew "lost their heads completely" at the shots across their bow,[5] adding to the confusion aboard a neutral-flagged vessel under fire in a time of war.