The class consisted of five dreadnought battleships ordered for the French Navy in 1912–1913, , the lead ship, , , , and . The design incorporated a radical arrangement for the twelve 340 mm (13.4 in) main battery guns: three quadruple-gun turrets, the first of their kind, as opposed to the twin-gun turrets used by most other navies. The first four ships were to be fitted with an unusual hybrid propulsion system that used both steam turbines and triple-expansion steam engines to increase fuel efficiency.
The ships were never completed due to shifting production requirements and a shortage of labor after the beginning of World War I in 1914. The first four ships were sufficiently advanced in construction to permit their launching to clear the slipways for other, more important work. Many of the guns built for the ships were converted for use by the Army. After the war, the French Navy considered several proposals to complete the ships, either as originally designed or modernized to account for lessons from the war. The weak French post-war economy forestalled these plans, and the first four ships were broken up.
The last ship, , which was not significantly advanced at the time work halted, was converted into an aircraft carrier in the 1920s. She remained in service in various capacities until the 1960s, and was ultimately scrapped in 1967.
Development
In December 1911, the French Navy's Technical Committee () issued a report that examined the design of the that had been ordered for 1912. They concluded that the amidships gun turret was an unsatisfactory choice, based on experiences from the 1880s with blast damage on battleships from their own guns. This position influenced the construction of the next class of dreadnought battleships, for which design work began shortly thereafter.
The French Navy's design staff () submitted the first draft of the new dreadnought design in February 1912. The size of French shipyard facilities significantly affected the design. Length was limited to , beam to , and draft to approximately . These dimensions limited the design to a displacement of around and a speed of , depending on the armament arrangement.
The design staff presented three armament alternatives, all armed with a secondary armament of twenty guns in a new twin-gun casemate mounting. The first was a design with the same ten 340 mm guns as the s, but with a top speed greater than 21 knots. The second was for a ship with a dozen 340 mm guns arranged in two quadruple-gun turrets fore and aft of the superstructure with superfiring twin-gun turrets and a speed of 20 knots. The last proposal was a ship that was armed with sixteen guns in four quadruple turrets and a speed of 20 knots.
The staff also prepared two design options for the propulsion system. One used two sets of direct-drive steam turbines, as in the class; the one ultimately selected was a hybrid system that used one set of direct-drive turbines on the two inner propeller shafts, and two vertical triple-expansion steam engines (VTE) on the outer shafts for low-speed cruising. This was intended to reduce coal consumption at cruising speeds, as direct-drive turbines are very inefficient at moderate to low speeds. The fifth ship, , was instead equipped with two sets of turbines to allow her to match the fuel consumption rate of the turbine-equipped class.
The General Staff decided in March 1912 to retain the 340 mm gun of the class and favored the all-turbine design. They chose the new quadruple turret and preferred an armament of twelve guns in two quadruple and two double turrets. The following month, the Naval Supreme Council () could not reach a decision on the quadruple turret as it was still being developed, but wished to revisit the issue once it was further along. The council rejected the twin-gun casemate mounting proposed for the secondary armament and proposed a mixture of eighteen 138.6 mm and a dozen guns. It accepted the hybrid propulsion system, and the armor layout of the class was to be retained, with an increase in the thickness of the main belt if possible. Théophile Delcassé, the Naval Minister (), accepted the council's recommendations with the proviso that the -class arrangement of five twin turrets, including one amidships, would be substituted if the quadruple turrets were not ready in time.
The Technical Department prepared two new designs, A7, which incorporated the five twin turrets, and A7bis, with three quadruple turrets. The A7bis design was some lighter than the A7 design, and on 6 April the Navy accepted a quadruple-gun-turret design submitted by Saint-Chamond. On 22 May it realized that the 100 mm gun would not ne ready by the time construction was scheduled to begin, so the design reverted to the 138.6 mm gun. Further work revealed that two additional guns could be accommodated, and the Naval Supreme Council accepted the design with twenty-four 138.6 mm guns on 8 July.
Description The -class ships were long at the waterline, and long overall. They had a beam of and a mean draft of at full load. They were intended to displace at normal load and at deep load. The ships were subdivided by transverse bulkheads into 21 watertight compartments.
The first four ships were equipped with one set of steam turbines driving the inner pair of four-bladed, propellers. and had license-built Parsons turbines, had turbines by Rateau-Bretagne, and s turbines were built by Schneider-Zoelly. The four ships had a pair of four-cylinder vertical triple-expansion engines that drove the two outer three-bladed, propellers for steaming astern or cruising at low speed. The last ship, , was equipped with two sets of Parsons turbines, each driving a pair of three-bladed, 3.34 m propellers. and were fitted with 21 Guyot-du Temple-Normand small-tube boilers, and were equipped with 28 Belleville large-tube boilers, while had 28 Niclausse boilers. All of the boilers operated at a pressure of .
The ships' engines were rated at and were designed to give them a speed of , although use of forced draft was intended to increase their output to and the maximum speed to . The ships were designed to carry of coal and of fuel oil, but up to of coal could be stored in the hull. At a cruising speed of , the ships could steam for ; at , the range fell to , and at top speed, it dropped to . The ships would have had a crew of 44 officers and 1,160 enlisted men when serving as a flagship.
Armament The main battery of the class consisted of a dozen 45-caliber Canon de 340 mm Modèle 1912M guns mounted in three quadruple turrets. One turret was placed forward, one amidships, and one aft, all on the centerline. The turrets weighed , and were electrically trained and hydraulically elevated. The guns were divided into pairs and moved together in twin cradles; a -thick bulkhead divided the turrets in half. Each pair of guns had its own ammunition hoist and magazine. They could be fired simultaneously or independently. Had the ships been completed, these would have been the first quadruple turrets in the world.
The guns had a range of and a rate of fire of two rounds per minute. The shells were armor-piercing rounds and were fired with a muzzle velocity of . Each gun was to have been supplied with 100 rounds of ammunition. Five rangefinders provided fire-control for the main battery. Two of the rangefinders were mounted on the conning tower and the other three were placed atop each of the turrets. The turrets also had auxiliary gunnery-control stations.
The ships would also have been armed with a secondary battery of twenty-four 55-caliber 138.6 mm Modèle 1910 guns, each singly mounted in casemates near the main-gun turrets. These guns fired a shell at a muzzle velocity of . These guns would have been supplied with 275 rounds of ammunition each. Six Canon de Modèle 1902 anti-aircraft guns, which were converted from low-angle guns, would also have been carried by the ships. The ships also would have been equipped with six underwater torpedo tubes, three on each broadside, and carried 36 torpedoes.
Protection
The armor belt of the -class ships was made from Krupp cemented armor and extended almost the entire length of the hull (), save at the stern. The belt consisted of two rows of plates that were a total of high, of which was below the waterline. The thickest portion of the armor protected the hull between the barbettes of the end turrets and was thick. Each of the upper plates was tapered to a thickness of at its top edge and the lower plates were tapered to at their bottom edge. From No. 1 barbette to the bow, the plates progressively reduced in thickness from at the bow; the upper edges also progressively reduced from while the bottom edge of these plates was thick. Aft of the rear turret, the armor plates were progressively reduced in thickness from 260 millimeters to 140 millimeters. Their upper edges also progressively thinned from , and their lower edges were the same 80 millimeters in thickness as their forward equivalents. The aft belt terminated in a transverse bulkhead.
Above the waterline belt was an upper strake of 160-millimeter armor that extended between the fore and aft groups of casemates for the secondary armament. The portions of the barbettes that extended outside the upper armor were protected by plates, while the interior surfaces were only thick to save weight. The turrets were protected with an armor thickness of 300 millimeters on their faces, on the sides, and 100 millimeters on the roof. The sides of the conning tower were thick and its roof was also 100 millimeters thick. The lower armored deck consisted of a single plate of mild steel for a width of along the centerline, and another layer of the same thickness was added outboard of that. The deck sloped downwards to meet the bottom of the waterline belt, and a plate of armor steel reinforced the sloped portion of the deck to give a total thickness of . Two layers of plating made up the center of the upper armored deck, which was reinforced to a total of along the edges and above the magazine.
The hull of the s had a double bottom deep. Their propulsion machinery spaces and magazines were protected by a torpedo bulkhead that consisted of two layers of nickel-chrome steel plates. The outer side of the bulkhead was lined with a 10-millimeter plate of corrugated flexible steel intended to absorb the force of a torpedo detonation. Another measure intended to dissipate the force were tubes that extended from the double bottom to the upper armored deck, intended to divert the gases of a detonation away from the torpedo bulkhead. Concerned about the possibility of capsizing after asymmetric flooding, the design incorporated empty compartments below the waterline and outboard of the fore and aft 34-centimeter magazines, the engine rooms and the midships 138.6-millimeter magazines that were intended to be flooded if necessary to correct any list.
Ships + Construction data Ship Builder Laid down Launched In Service Fate , St Nazaire 18 April 1913 19 October 1914 — Incomplete, scrapped 1924–1925 , Brest1 October 1913 20 October 1914 — Incomplete, scrapped October 1924 , Lorient 20 September 1914 — Incomplete, scrapped 1923–1924 , Lormont 1 May 1913 1 May 1915 — Incomplete, scrapped June 1929 , La Seyne-sur-Mer 5 January 1914 15 April 1920 May 1927 Converted to an aircraft carrier, scrapped 1967
Construction and cancellation
Named after provinces of France, and were ordered on 18 April 1913, although neither was formally authorized until the enabling finance bill () was passed on 30 July, and and on that same day. had been planned to be ordered on 1 October 1914, but it was brought forward to 1 January; the five ships would permit the creation of two four-ship divisions with the three -class dreadnoughts then under construction.