The 340mm/45 Modèle 1912 gun (13.4") was a heavy naval gun of the French Navy. While the calibres of the naval guns of the French Navy were usually very close to those of their British counterparts, the calibre of 340 mm is specific to the French Navy. The built-up gun was designed to be carried by the Normandie and Lyon classes in quadruple gun turrets, but no ship of these types was completed as a battleship. They were carried by the Bretagne-class battleships in twin turrets.