This film and also "13 Rue Madeleine" are loosely based on the real exploits of one of the few US Marines to serve in combat in the European Theater, WW2. A former Foreign Legionnaire, Colonel Peter Julien Ortiz, USMC Ret, was an officer with the OSS and led Operations Union I & II in southern France training, supplying and leading the Resistance against the Germans in 1944-45. His actual adventures earned him two Navy Crosses and were so incredible you'd hardly believe them in a movie.