With the war over, the British contingent of the American Cruiser and Transport Force withdrew, leaving the United States with insufficient tonnage needed to quickly repatriate U.S. troops from Europe.
To rectify the problem, a total of 56 ships under the control of the U.S. government, including Black Arrow, were selected for conversion into troop transports.

Black Arrow was converted by the Morse Dry Dock and Repair Company of Brooklyn between 17 January and 15 March 1919, at a cost of $170,938—in the process becoming the first ship raised by the Morse Company's new floating dock, the largest of its type in the world.
While still undergoing conversion, the ship was commissioned into the U.S. Navy on 27 January as USS Black Arrow (ID-1534), with Lieutenant Commander Walter S. Lynch, USNRF, placed in command.
After conversion, the ship had a passenger capacity of 85 officers and 1,510 enlisted men, and a crew complement of 21 officers and 96 enlisted men,
Black Arrow subsequently made three round trips between the United States and France to repatriate troops.
On the first of these, the ship departed New York for Brest, France on or about 6 April,  making the return voyage between 26 April and 6 May, carrying artillery units of 82nd Division and a variety of other troops including a heavy mobile ordnance repair shop, the 34th evacuation hospital and casual units—1,585 men in total.
Departing New York 13 May, Black Arrow returned to Brest, then continued on to Bordeaux before clearing that port on the 31st for Newport News, Virginia, where on 13 June she arrived to disembark eight casual and two transportation companies, a bakery company, the 20th evacuation hospital and several sanitary squads.
Black Arrow's third and final repatriation voyage departed Bordeaux 7 July, arriving at New York on or about the 20th with nine motor companies, the 713th service park company, 53d guards company, ten casual companies and miscellaneous troops.
Altogether, Black Arrow returned a total of 4,759 troops to the United States on her three troop repatriation voyages, including 25 sick or wounded.

With her naval service complete, Black Arrow was decommissioned at Norfolk, Virginia, on 9 August 1919—thus reverting to the name SS Black Arrow—struck from the Naval Vessel Register the same day, and returned to the control of the United States Shipping Board.
With the war over, the British contingent of the American Cruiser and Transport Force withdrew, leaving the United States with insufficient tonnage needed to quickly repatriate U.S. troops from Europe. To rectify the problem, a total of 56 ships under the control of the U.S. government, including Black Arrow, were selected for conversion into troop transports.
Black Arrow was converted by the Morse Dry Dock and Repair Company of Brooklyn between 17 January and 15 March 1919, at a cost of $170,938—in the process becoming the first ship raised by the Morse Company's new floating dock, the largest of its type in the world. While still undergoing conversion, the ship was commissioned into the U.S. Navy on 27 January as USS Black Arrow (ID-1534), with Lieutenant Commander Walter S. Lynch, USNRF, placed in command. After conversion, the ship had a passenger capacity of 85 officers and 1,510 enlisted men, and a crew complement of 21 officers and 96 enlisted men,
Black Arrow subsequently made three round trips between the United States and France to repatriate troops. On the first of these, the ship departed New York for Brest, France on or about 6 April,  making the return voyage between 26 April and 6 May, carrying artillery units of 82nd Division and a variety of other troops including a heavy mobile ordnance repair shop, the 34th evacuation hospital and casual units—1,585 men in total. Departing New York 13 May, Black Arrow returned to Brest, then continued on to Bordeaux before clearing that port on the 31st for Newport News, Virginia, where on 13 June she arrived to disembark eight casual and two transportation companies, a bakery company, the 20th evacuation hospital and several sanitary squads. Black Arrow's third and final repatriation voyage departed Bordeaux 7 July, arriving at New York on or about the 20th with nine motor companies, the 713th service park company, 53d guards company, ten casual companies and miscellaneous troops. Altogether, Black Arrow returned a total of 4,759 troops to the United States on her three troop repatriation voyages, including 25 sick or wounded.
With her naval service complete, Black Arrow was decommissioned at Norfolk, Virginia, on 9 August 1919—thus reverting to the name SS Black Arrow—struck from the Naval Vessel Register the same day, and returned to the control of the United States Shipping Board.
USS Black Arrow