Guy didn’t know much about the history of the Swiss.
They fought several civil wars, some of them religious.
They also provided most of the best mercenaries of Europe for several centuries, and had a rep for giving no quarter.
Graham Greene wrote the brilliant screenplay for The Third Man and it was directed by Carol Reed. The movie really stars Joseph Cotton with a smaller but charismatic role for Orson Welles. That line is the most remembered of the movie (as is the score) and is spoken by the wily Harry Lime.