After her navy service ended, she was SS Siboney for the New York & Cuba Mail Steamship Co. (commonly called the Ward Line).

During World War II she served the U.S. Army as transport USAT Siboney and as hospital ship USAHS Charles A. Stafford.

Renamed USAHS Charles A. Stafford after a U.S. Army doctor killed in action in Australia, the ship served in both the European and the Pacific Theatres.

[6] Siboney sailed from Philadelphia on 16 April as a unit of the Cruiser and Transport Force, and arrived at Newport News two days later to embark her first contingent of troops.

[7] Siboney returned to New York on 2 September at the conclusion of her 17th trip, having traveled over 115,000 nautical miles (213,000 km) and transported approximately 55,000 military passengers to and from French ports.

[8] On 10 September at Hoboken, Siboney was decommissioned and turned over to the War Department, who returned the ship to the Ward Line, her original owners.

[6] After her reacquisition, the Ward Line placed SS Siboney in transatlantic service on a New York to Havana, Tenerife, Bilbao, Santander, and Vigo route.

[10][11] Despite considerable damage, Siboney was refitted and placed in service again and, by March 1921, the Ward Line was advertising passage to Spain via Havana aboard her.

On 27 June 1922, Siboney—freshly returned from Havana with a load of pineapples—was raided by United States Customs Service inspectors who seized 300 bottles of smuggled liquor on board.

[16] In December 1923, four boiler room workers were arrested when police became suspicious of a man who had apparently just delivered a supply of alcohol to the docked ship.

[17] Siboney underwent a major refit in 1924 during which time she was replaced on her routes by SS Yucatán, formerly the North German Lloyd ship Prinz Waldemar.

[21] By 1939, Siboney, still on the New York–Cuba–Mexico route, sported a new paint scheme of "dove grey" hull and black funnels with white markings to reflect this change in name.

[12][23] During her American Export service, one of her passengers to the U.S. was French aviator and writer Antoine de Saint-Exupéry, when he emigrated in January 1941 to Asharoken, New York after Germany's armistice with France.

[26] At the conclusion of her seventh and final journey for American Export, Siboney was placed under time charter for duty as an Army transport.

Based in New York, she made trips up and down the Atlantic and into the Caribbean, and, by the end of 1941, had called at Bermuda, San Juan, Trinidad, St. John's, Charleston, Newport News, Cristóbal, Jamaica, and Panama.

[3] December 1941 saw Siboney depart from New York to Trinidad and on to Cape Town, then sailing up the east coast of Africa to Basra, Iraq, and Bandar Shahpur, Iran.

After undergoing six weeks of repairs at Bethlehem Steel Company, the transport sailed for Halifax, Iceland, and the Clyde, Scotland, in late May, returning to New York in July.

[27] In early December 1942 Siboney departed for Newfoundland but put into Halifax for two months of drydocking and repairs after she collided with SS City of Kimberly.

After returning to New York in February 1943, she made several transatlantic runs, calling at Casablanca, Oran, Gibraltar, Clyde, Durban, Rio de Janeiro, Trinidad, and Cuba over the next 11 months.

With her conversion complete in September 1944, the Stafford, equipped with new boilers, a single stack in place of her original two, and other improvements, moved to her new homeport of Charleston.