SS Munargo was a commercial cargo and passenger ship built for the Munson Steamship Line by New York Shipbuilding Corp., Camden, New Jersey launched 17 September 1921.

[7] Munagro was set for her first commercial voyage on 7 January 1922 with accommodations for 297 passengers with all outside staterooms, an open verandah lounge and an 11,000 mile cruising range with plans to alternate the New York-Bahamas-Cuba-Miami service with the line's other ship Munamar.

[2][5] In June 1930 the ship took the Mexican and United States teams to the 1930 FIFA World Cup in Uruguay in an eighteen-day voyage from New York with stops at Rio de Janeiro and Santos, Brazil.

She departed 19 December for San Juan, Puerto Rico, with troops and civilian passengers, and thence steamed to Trinidad to take aboard suspected German agents for transportation to New York, arriving 5 January 1942.

[3] Munargo left New York 30 December with troops, cargo, and U.S. currency for Trinidad and Brazil, from which she sailed through the Panama Canal to San Francisco, California, arriving 18 March 1943.

[17] Under supervision of the Maintenance and Repair Branch of the Water Division at the New York Port of Embarkation converted Munargo to a hospital ship with the new name Thistle with a patient capacity of 455 making her first voyage to North Africa on 8 April 1944.

[21] Pressure to transport dependents reached Congressional level and in response, though Congress withdrew a resolution forcing Army to comply, about 30 vessels, the majority Army troop or hospital ships were designated for partial conversion to more suitable transports, including provision of "Cribs, high chairs, play pens, and baby baths" and special laundry facilities.

[23][24] The ship was active in this role when on 17 January 1948 USAT Thistle was reported in Pacific Stars and Stripes as having arrived that morning in Yokohama with "220 dependents, 38 enlisted men, three officers, 11 school teachers and ten DACs" (Department of Army Civilians) after a seventeen-day voyage from Seattle.

[citation needed] Thistle was declared surplus by the Army, returned to the Maritime Commission and laid up in the National Defense Reserve Fleet, Astoria, Oregon 1 November 1948.