Built at William Cramp & Sons Shipbuilding Company in Philadelphia, the vessel was completed in April 1917. She was named Santa Paula and entered commercial service for the Grace Line.[3]
After the United States entered World War I, the vessel was requisitioned by the US Navy in August 1918 and became the commissioned USS Santa Paula ID-1590.[4] She was assigned to the Naval Overseas Transportation Service to carry cargo for United States forces fighting in France. She only completed one round-trip voyage, from New York to Marseilles and back, with 8,340 tons of general cargo, before the war ended.[5]
Santa Paula again sailed to Marseilles between 21 November and 14 January 1919, with supplies for US forces still in France. She was then transferred to the Cruiser and Transport Force. In late January, American troops home from France and would make four more round-trip voyages from New York to Brest Bordeaux and St. Nazaire between 22 March and 1 August. When the last of these voyages ended at New York, the ship was turned over to the custody of the Commandant, 3d Naval District, and was decommissioned on 21 August 1919 and simultaneously returned to the Grace Line.[5]
Santa Paula resumed service for the Grace Line. By 1925, the Intracoastal service had become unprofitable. However, the American-Hawaiian Steamship Company sought to expand its Pacific service and negotiated the purchase of six ships, including Santa Paula, from the Grace Line. She was renamed SS Montanan (American-Hawaiian's first SS Montanan had been sunk in World War I) and entered Pacific intercoastal service for her new owners.[6] During her inter-war service, she carried goods from Los Angeles and San Francisco to the Canal Zone and also made coastal voyages.[7]
Montanan was sailing as a civilian transport vessel in the Arabian Sea on June 3, 1943. She was sunk 150 nautical miles (280 km; 170 mi) south of Masirah Island, Oman, by the Imperial Japanese Navy submarine I-27[5][8] At 0735 a torpedo struck on the starboard side of the No. 2 hold, igniting the bunker fuel tanks and sending flames up the foremast. Just seven minutes later the ship sank bow first. Master Charles Harry McGahan was killed along with four other crew members and two of the Armed Guard. Survivors either jumped overboard or boarded her four lifeboats. Survivors in Life Boat No. 2 sailed for two days before rescue by the dhow Naranpasha. They were transferred to the armed trawler HMIS Baroda and arrived at Port Okha on June 11, 1943. Survivors in the other boats reached Masirah Island.[9]
^"Indian Ocean - Red Sea 1943". U.S. Ships Sunk or Damaged in South Atlantic, Indian Ocean and Red Sea During World War II. American Merchant Marine at War, www.usmm.org. Archived from the original on 30 September 2012. Retrieved 8 October 2012.