Mimoun's running career was interrupted when he was called up to fight for the Western Allies in the Tunisia Campaign and then in the Italian Campaign. In the Tunisia Campaign, he fought under the command of General Henri Giraud against the Afrika Korps. In July 1943, he was sent to fight in the Italian Campaign, where he was a lance corporal in the 83rd combat engineers battalion of the Algerian 3rd infantry division of the French Expeditionary Corps commanded by Marshal Alphonse Juin.