When World War II broke out in 1939, he was mobilised as a non-commissioned officer in the train transport corps. According to his official biography, he helped Jewish people to escape Nazi persecution following the July 1942 mass arrests in Paris, called the "Rafle du Vel' d'Hiv", and another raid in the area of Grenoble in the non-occupied zone: "In July 1942, two fleeing Jews asked him for help. Having discovered the persecution taking place, he immediately went to learn how to make false passports. Starting in August 1942, he guided Jewish people to Switzerland".