Lyon-class battleship

The Lyon class was a proposed type of battleship which was planned for the French Navy in 1913, with construction scheduled to begin in 1915. The class was to have comprised four ships: Lyon, Lille, Duquesne, and Tourville. The first two were named for cities in France, while the rest honored French admirals Abraham Duquesne and Anne Hilarion de Tourville. The design was an improvement on the previous Normandie-class battleship, and mounted a fourth quadruple gun turret, for a total of sixteen 340 mm guns. Construction was cancelled due to the outbreak of World War I in August 1914 before any of the ships could be laid down.

Design
Starting in 1910, the French Navy began a dreadnought battleship construction program, starting with the four ships of the Courbet-class battleship that year. The three-ship Bretagne-class battleship was authorized the next year, and five Normandie-class battleships followed in 1912. Design work began in 1912; the design staff submitted several proposals for the new battleships. Displacements ranged from 27000 MT to 29000 MT; the various designs featured a main battery of fourteen or sixteen 340 mm guns, eight or ten 380 mm guns, or twenty 305 mm guns, in a mix of quadruple or twin gun turrets.

In 1913, the Navy authorized a fourth class of battleships, Lyon, which was scheduled for 1915. The design staff determined the 38 cm gun would take too long to design, so the proposals that incorporated these weapons were cancelled. The design staff settled on one of the two 34 cm proposals. The first proposal, which mounted fourteen guns, was a 27500 MT ship 185 m long. On 24 November 1913, the design staff instead chose the slightly larger second design, armed with sixteen guns in four quadruple turrets. The first two ships, Lyon and Lille, were scheduled to be ordered on 1 January 1915, and Duquesne and Tourville would have followed on 1 April 1915. World War I broke out in August 1914, however, and shifting military requirements, particularly for the army, forced the cancellation of the class.

Characteristics
The ships would have been 190 m long between perpendiculars and 194.5 m long overall. They would have had a beam of 29 m and a draft of 8.65 to 9.2 m. Their full load displacement was estimated at 29000 MT. The propulsion system had not been settled by the time the class was cancelled; the design staff proposed either the mixed steam turbine and triple expansion engine system used in the first four ships of the preceding Normandie class or the all-turbine system used in the last ship of the previous class, Béarn. They also considered new geared turbines that had proved satisfactory in the new destroyer Enseigne Gabolde. The final design called for a propulsion system rated at 43000 shp with a top speed of 23 kn. An unknown number of boilers were trunked into two funnels amidships.

Sixteen 340mm/45 Modèle 1912 guns mounted in four quadruple turrets comprised the main battery. The turrets, which were equipped with electric-hydraulic training and elevation gear, were all mounted on the centerline, though the arrangement is not clear. According to Conway's All the World's Fighting Ships, one turret was placed forward, one amidships, and two in a superfiring pair aft. The contemporary Journal of United States Artillery, however, suggests the turrets would have been mounted in two superfiring pairs, forward and aft. The turrets weighed 1500 MT, and were electrically trained and hydraulically elevated. The guns were divided into pairs and mounted in twin cradles; a 40 mm thick bulkhead divided the turrets. Each pair of guns had its own ammunition hoist and magazine. They could be fired simultaneously or independently. The guns had a range of 16000 m and had a rate of fire of two rounds per minute. The shells were 540 kg armor-piercing rounds and were fired with a muzzle velocity of 800 m/s.

The secondary battery was to consist of twenty-four guns, either the 138.6 mm /55 Modèle 1910 or a new automatic model, each singly-mounted in casemates in the hull. The M1910 guns fired a 36.5 kg shell at a muzzle velocity of 830 m/s. The ships would also have been equipped with an unknown number of 40 mm or 47 mm anti-aircraft guns and six torpedo tubes of unknown size, submerged in the hull. The ships would have been protected with a variation of the armor layout of the previous Normandie class. The primary alterations were slightly thinner casemate armor and upper deck plating to compensate for improved armor below the waterline.