The first full screenplay of Bryan Forbes
The French Government named the overland escape route used by mission marines W.E. Sparks and H.G. Hasler, the two real life survivors of Operation Frankton, the Frankton Trail.
The last feature of Patric Doonan.
The movie is based on the small boat unit called the Royal Marines Boom Patrol Detachment which was formed by Major H. G. Blondie Hasler (H.G. Hasler) during World War II. This movie is based on their adventures from their first mission and the book that documented them, 'Cockleshell Heroes '. The anchor character of Major Stringer (José Ferrer in this movie is derived from Hasler.
The movie's marketing had film posters celebrating the marines as the "Canoe Commandos".
The opening scenes of this movie include the reminiscences of Bill Sparks, one of the two survivors of the real-life Operation Frankton.
The Royal Marines and the Commandant-General Royal Marines trained this movie's actors in marine skills, performing drill and canoe sailing.
This film's closing epilogue states: "The producers gratefully acknowledge the assistance given to them in the making of the film by the Royal Marines and other branches of the Royal Navy."
This film's opening prologue states a brief history of the Royal Marines from 1664 to 1942's Second World War Operation Frankton.
This movie had three working titles. They were: 'Survivors Two', 'Canoe Commandos' and 'The Survivors'.
This movie's budget was considered expensive during the era in which it was produced.
Though the operation in the film is known as Operation Cockleshell, the real name of the operation to which the film was based on was Operation Frankton. It was conducted by twelve men of the Royal Marines Boom Patrol Detachment in December 1942.
Trevor Munn in his Trevor Howard biography, 'Trevor Howard: The Man and His Films', states: "What Trevor didn't say was that José Ferrer directed and José Ferrer starred and in the process didn't make himself too popular with Irving Allen. At the time Allen said, 'When Ferrer finished the film, we found that he had made a tour de force for José Ferrer. He seems to have forgotten about the rest of the cast. I've been doing close-ups of Trevor Howard that Joe forgot to do.'"