SS Montanan was a cargo ship built in 1912 for the American-Hawaiian Steamship Company. During World War I service for the United States Army Transport Service, she was known as USAT Montanan. Montanan was built by the Maryland Steel Company as one of eight sister ships for the American-Hawaiian Steamship Company, and was employed in inter-coastal service via the Isthmus of Tehuantepec and the Panama Canal after it opened.

SM U-90 was a Type U-87 U-boat of the Imperial German Navy during World War I. Its commander Walter Remy made regular stops at remote island North Rona for provisions such as fresh mutton. On 15 May 1918, U-90 shelled the Hirta wireless station in St Kilda, Scotland. On 31 May 1918, U-90 torpedoed and sank USS President Lincoln, a former Hamburg America Line steamer that had been seized by the United States for troop transportation. From the U.S. Navy crew that abandoned the sinking vessel, U-90 captured Lieutenant Edouard Izac, eventually taking him to Germany. Izac later escaped German captivity and reported to the US Navy about German submarine movements.