Inspired by the Oradour tragedy.
Because her parents were close to the wartime Nazi regime, the flamethrower sequence was traumatic for Romy Schneider. She later confessed that she did not play the character, she WAS the character. The sequence was not shown to German audiences.
Lino Ventura was asked to be Philippe Noiret 's character but refused because it was too violent for him.
According to director Robert Enrico in his biography, on the set of this film Romy Schneider could not bear Philippe Noiret anymore. She found him rude.
Philippe Noiret was very upset from the beginning of the shooting because Romy Schneider was always late on the set. But he rapidly came to her and reassured her with great care.