Lagrange-class submarine

The "Lagrange"-class submarines were a class of foursubmarines built for the French Navy during World War I and the interwar period. Threeships of this type were built in the Arsenal de Toulon from 1913 to 1924, and onewas built at the Arsenal de Rochefort shipyard. Entering the French "Marine Nationale" from 1918 to 1924, the submarines served until the mid-1930s.
Design.
The "Lagrange"-class submarines were constructed as part of the French fleet's expansion programmes from 1913 to 1914. The ships were designed by Julien Hutter, who slightly modified his previous project, the s, using two Parsons steam turbines with a power of . During construction, though, the idea was abandoned and the ships were instead equipped with diesel engines.
 long, with a beam of and a draught of , "Lagrange"-class submarines could dive up to . The submarines had a surfaced displacement of and a submerged displacement of . Propulsion while surfaced was provided by two diesel motors built by Swiss manufacturer, Sulzer, and two electric motors. The submarines' electrical propulsion allowed them to attain speeds of while submerged and on the surface. They had surfaced range of at and a submerged range of at .
The ships were equipped with eight torpedo tubes (fourin the bow; twostern and twoexternal), with a total of tentorpedoes and two guns. The crew of a ship comprised forty-sevenmen.
Ships.
Of the four"Lagrange"-class submarines, threewere built in the Arsenal de Toulon and one in the Arsenal de Rochefort. The ships were laid down between 1913 and 1914 and launched between 1917 and 1924. The ships were named after French scholars: Joseph-Louis Lagrange, Pierre-Simon Laplace, Henri Victor Regnault and the constructor of submarines Gaston Romazzotti.
Service.
Of the foursubmarines, only twowere commissioned before the end of World War I: "Lagrange" and "Romazzotti", which operated in the Mediterranean Sea.
From 1922 to 1923, the ships underwent a major refit in which they received new major conning towers, bridges and periscopes. All ships served in the Mediterranean Sea until 1935 for "Lagrange" and 1937 for the other threeships.