While being a bank clerk in 1942, Paris-born Roger Masmonteil published his first illustrations in Allô 18, the magazine of the firemen where he fulfilled his military service during the War. Back in civil life, Mas returned to his work at a bank. He eventually found employment as the successor of José Cabrero Arnal on his series 'Gavroche et G. Latine' in Avant-Garde and 'Becdor le Canard' in L'Humanité. In addition, Mas illustrated 'Barbichette', created with a script by Jean-Claude, also in L'Humanité.