Canopus was launched in 1919 by New York Shipbuilding Company, Camden, New Jersey, as the passenger liner SS Santa Leonora for W. R. Grace and Company, but taken over by the Navy upon completion in July 1919 and placed in commission at that time as USS Santa Leonora. She was briefly employed as a trans-Atlantic troop transport before being decommissioned and transferred to the U.S. Army in September 1919.