The story was inspired by events in Louis L'Amour's life when he served in the European campaign. Louis L'Amour for those who may not know was a prolific writer of Westerns and single-handedly reinvented that literary form.
He told his WWII tales at the Brown Derby on Vine Stree in Hollywood. Louis often met with Cobb who ran the place. They often spoke of American Natives especially the Crow Indians in Wyoming and Montana. In any case, someone overheard Louis's WWII tales and it became this film.
I don't know if Louis L'Amour was ever credited. I don't think so. Much of this author's early life could easily serve as an exciting source of several entertaining and illuminating films.