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. On 28 January 1944, during the Battle of Monte Cassino, Mimoun was seriously injured by fragmentation in his left leg originating from shells fired by the Germans. American doctors working in the field hospital recommended its amputation. Determined not to lose his leg, he refused. Fortunately, a French surgeon there managed to successfully perform an operation and his left leg was saved. He was later sent to a Naples hospital for convalescence. He recovered sufficiently to the extent that he could still engage in military combat in the last part of World World II. In the summer of 1944, Lance Corporal Mimoun participated in the Allied invasion of France from the Mediterranean Sea. After that campaign, he was involved in the liberation of the Jura Mountains from the German troops. He spent the winter of 1944–1945 in the Vosges Mountains before taking part in the Western Allied invasion of Germany. He spent about one year in Germany.