The Canon de 138 mm Modèle 1910 was a medium calibre naval gun of the French Navy

French Navy

The French Navy, officially the Marine nationale and often called La Royale is the maritime arm of the French military. It includes a full range of fighting vessels, from patrol boats to a nuclear powered aircraft carrier and 10 nuclear-powered submarines, four of which are capable of launching...

 used during World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 and World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. It was carried by the dreadnoughts of the Courbet

Courbet class battleship

The Courbet class battleships were the first dreadnoughts built for the French Navy before World War I. The class comprised four ships: , , , and . All four ships were deployed to the Mediterranean Sea for the entirety of World War I, spending most of their time escorting French troop convoys from...

 and Bretagne

Bretagne class battleship

The Bretagne class battleships were the first "super-dreadnoughts" built for the French Navy during the First World War. The class comprised three vessels: Bretagne, the lead ship, Provence, and Lorraine. They were an improvement of the previous , and mounted ten guns instead of twelve guns as on...

 classes as their secondary armament and planned for use in the Normandie class battleship

Normandie class battleship

The Normandie-class dreadnought battleships were ordered for the French Navy before the First World War. They were named after provinces of France. These ships were never completed as battleships because the war stopped their construction...

s. It was used as the primary armament for the Arras-class sloops and planned for the light cruiser Lamotte Picquet that was canceled in 1915. It was also used in coast defense batteries during both World Wars.

Design

The 55 caliber Mle 1910 used the typical built-up construction of its time. It had a screw breech and used separate-loading ammunition. In the battleships it was installed in armored casemates, using central pivot mounts, but no details are available. Presumably a variant of this mount was used for the sloops. Initially the casemate mount had a range of elevation from -10° to +15°, but this was later changed to -7° to +25°. The casemate mount could traverse a total of 160°.

Ammunition

The 10.4 kilograms (22.9 lb) propellant charge for the Mle 1910 was contained in a cartridge case that would be used for all succeeding French guns of this caliber. Of course the actual amount of powder would vary with each gun, but it standardized the chamber size for all 138.6 mm (5.5 in) French guns.

Shell type	Weight	Muzzle velocity	Range
semi-armor piercing Armor-piercing shot and shell An armor-piercing shell is a type of ammunition designed to penetrate armor. From the 1860s to 1950s, a major application of armor-piercing projectiles was to defeat the thick armor carried on many warships. From the 1920s onwards, armor-piercing weapons were required for anti-tank missions...	39.5 kg (87.1 lb)	790 m/s (2,591.9 ft/s)	16.1 km (17,607.2 yd)
high-explosive	31.5 kg (69.4 lb)	840 m/s	15.1 km (16,513.6 yd)

Coast defense duties

Twenty Mle 1910 guns were used by the Germans as coast defense guns along the French Mediterranean coast, although it is unclear if these guns were simply taken over by the Germans or if they were emplaced by them.