John Ireland replaced Wendell Corey who was forced to drop out of the role of William Quantrill due to illness.
During shooting, John Farrow took over direction for a few days when William Dieterle was stricken with a virus infection. Farrow's work is uncredited on screen credits.
Location shooting took place near Gallup, NM, at six different camps. Navajo Indians from a nearby reservation were recruited as extras, and Chief Long Bow, a full-blooded Pueblo Indian, acted as translator.
Alan Ladd and Arthur Kennedy both served in the First US Motion Picture Unit of the US Army Air Forces in World War II.