Launched in 1931, the SS Mariposa was initially a luxury ocean liner among the quartet of vessels within the Matson Lines’ distinguished “White Fleet.” During World War II, it was repurposed and operated under the War Shipping Administration. It was closely linked with the US Army but was not formally classified as a US Army Transport. Functioning as a swift troop carrier, it facilitated the transportation of supplies and support forces to distant shores while conducting critical rescue missions for individuals stranded in foreign nations at the onset of the conflict. With a Navy-assigned troop capacity of 4,165 and a speed of 20.5 knots (38.0 km/h), the Mariposa belonged to the category of very large, rapid transports, commonly known as the “Monsters,” often navigating without an escort. Its conversion aimed to serve the US by swiftly ferrying troops, delivering essential supplies, and conducting rescues in regions affected by the war’s outbreak.

Source: Charles, Ronald W. “U.S. Army Center of Military History.” Troopships of World War II, History.Army.mil, Apr. 1947, history.army.mil/documents/WWII/wwii_Troopships.pdf.