The 203mm/55 Modèle 1931 gun was a medium naval gun of the French Navy. The type was used on the Algérie as main battery, mounted in four twin turrets. These guns used the same ammunition as the 203mm/50 Modèle 1924 gun and were very similar except for the longer bore. It is believed that the guns were built from tubes of elder 240mm/50 Modèle 1902 guns.