Sergeant X of the Foreign Legion (1960)

In order to pay off some major gambling debts, a drifter agrees to perform a dangerous job for his debtors. Things start to go wrong when he finds out that his girlfriend, thinking he has deserted her, marries another man. Despondent and depressed, he joins the French Foreign Legion to "get away from it all", but soon discovers that it's not as easy as he thought.