She was laid down as "Begum" (MC hull 1099), on 17 January 1943, by the Kaiser Shipbuilding Co., Inc., Vancouver, Washington, under Maritime Commission contract, named "Natoma Bay" on 22 January 1943, after a bay in the Graham Islands off the southwest coast of Alaska; launched on 20 July 1943; sponsored by Lady Halifax, wife of the United Kingdom's ambassador to the United States; and commissioned on 14 October 1943, Captain Harold L. Meadow in command.