Procyon was built in 1919 by the American International Shipbuilding Corp., Hog Island, Pennsylvania, and launched as the SS Shaume; taken over by the Navy on 8 November 1921 from the U.S. Shipping Board, under executive order of 29 October 1921; and commissioned on 30 November 1921, Lt. Bertram David in command. Procyon served as flagship of Commander Fleet Base Force, U.S. Battle Fleet, until she was decommissioned on 1 April 1931.