The Canon de 240 TR Mle 1903 sur affût-truck Mle 1914 was a French

railway gun A railway gun, also called a railroad gun, is a large artillery piece, often surplus naval artillery, mounted on, transported by, and fired from a specially designed railway wagon. Many countries have built railway guns, but the best-known are ...

and

siege gun Siege artillery (also siege guns or siege cannons) are heavy guns designed to bombard fortifications, cities, and other fixed targets. They are distinct from field artillery and are a class of siege weapon capable of firing heavy cannonballs o ...

used by the

French Army The French Army, officially known as the Land Army (french: Armée de Terre, ), is the land-based and largest component of the French Armed Forces. It is responsible to the Government of France, along with the other components of the Armed Force ...

during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

History

Before the First World War, the doctrine of the

was geared towards a war of rapid maneuver. Although the majority of combatants had heavy field artillery prior to the outbreak of the First World War, none had adequate numbers of heavy guns in service and once the Western Front stagnated and

trench warfare Trench warfare is a type of land warfare using occupied lines largely comprising military trenches, in which troops are well-protected from the enemy's small arms fire and are substantially sheltered from artillery. Trench warfare became ar ...

set in the light field guns that the combatants went to war with were beginning to show their limitations when facing an enemy who was now dug into prepared positions.

Indirect fire Indirect fire is aiming and firing a projectile without relying on a direct line of sight between the gun and its target, as in the case of direct fire. Aiming is performed by calculating azimuth and inclination, and may include correcting aim ...

interdiction Interdiction is a military term for the act of delaying, disrupting, or destroying enemy forces or supplies en route to the battle area. A distinction is often made between strategic and tactical interdiction. The former refers to operations whose ...

and

counter-battery fire Counter-battery fire (sometimes called counter-fire) is a battlefield tactic employed to defeat the enemy's indirect fire elements (multiple rocket launchers, artillery and mortars), including their target acquisition, as well as their command ...

emphasized the importance of long-range heavy artillery. Since aircraft of the period were not yet capable of carrying large diameter bombs the burden of delivering heavy firepower fell on the artillery. Two sources of heavy artillery suitable for conversion to field use were surplus coastal defense guns and

naval guns A navy, naval force, or maritime force is the branch of a nation's armed forces principally designated for naval warfare, naval and amphibious warfare; namely, lake-borne, riverine, littoral zone, littoral, or ocean-borne combat operations and ...

. However, a paradox faced artillery designers of the time; while large caliber naval guns were common, large caliber land weapons were not due to their weight, complexity, and lack of mobility. Large caliber field guns often required extensive site preparation because the guns had to be broken down into multiple loads light enough to be towed by a horse team or the few

traction engine A traction engine is a steam engine, steam-powered tractor used to move heavy loads on roads, plough ground or to provide power at a chosen location. The name derives from the Latin ''tractus'', meaning 'drawn', since the prime function of any t ...

s of the time and then reassembled before use. Building a new gun could address the problem of disassembling, transporting and reassembling a large gun, but it did not necessarily address how to convert existing heavy weapons to make them more mobile. Rail transport proved to be the most practical solution because the problems of heavy weight, lack of mobility and reduced setup time were addressed.

Design

* Gun - The Canon de 240 TR Mle 1903 sur affût-truck Mle 1914 was designed by Canet and manufactured by Schneider. It started life as a coastal defense gun called the ''Canon de 240 TR Mle 1884-1903 sur affût G Mle 1903.'' It was a typical

built-up gun A built-up gun is artillery with a specially reinforced barrel. An inner tube of metal stretches within its elastic limit under the pressure of confined powder gases to transmit stress to outer cylinders that are under tension.Fairfield (1921) p. ...

of the period made from steel with a rifled inner tube and reinforced by layers of external tubes. * Breech - The gun fired separate loading cased charges and projectiles in which bags of propellant were placed inside a brass case to vary range and velocity. The shell casing together with the breech provided

obturation In the field of firearms and airguns, obturation denotes necessary barrel blockage or fit by a deformed soft projectile (obturation in general is closing up an opening). A bullet or pellet, made of soft material and often with a concave base, ...

to seal the breech during firing. Since the cases could be filled with bags of propellant ahead of time and loaded more quickly than guns using only bagged propellant it was considered a rapid-fire gun and the "TR" in its name stood for ''tir rapide'' or rapid-fire in English. The guns had a Canet rotating block breech that was a bit unusua
as seen here
on a Canet gun. The breech was

semicircular In mathematics (and more specifically geometry), a semicircle is a one-dimensional locus of points that forms half of a circle. The full arc of a semicircle always measures 180° (equivalently, radians, or a half-turn). It has only one line o ...

in shape and was hinged at its center. When the breech was opened the projectile and casing were fed in and then the breech block was rotated 90° upward to seal the breech. When the gun fired the breech was opened, the case was ejected and the next round inserted. * Recoil System - The recoil system for the gun consisted of a U shaped gun cradle which held the

trunnion A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions a ...

ed barrel and a slightly inclined firing platform with a hydro-gravity recoil system. When the gun fired the hydraulic buffers on top and at the front of the cradle slowed the recoil of the cradle which slid up a set of inclined rails on the firing platform and then returned the gun to position by the combined action of the buffers and gravity. *Rail Carriage - Rather than being a true railway gun it was more of a multi-mode siege gun because the carriage built by St Chamond could be reconfigured to run on standard gauge rails, narrow gauge rails or fitted with road wheels like the

Mortier de 293 Danois sur affut-truck modèle 1914 The Mortier de 293 Danois sur affut-truck modèle 1914 was a French railway gun and siege gun used by the French Army during World War I and World War II. History Before the First World War, the doctrine of the French Army was geared towards a wa ...

which was similar in construction and configuration. In the center of the carriage, there were the two standard gauge 4-wheeled railroad

bogies A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of transp ...

that could be raised or lowered. There was also a narrow gauge 4-wheeled bogie at both ends that could also be raised and lowered. Lastly, jackscrews are provided on the car body for transferring from one set of trucks to the other. Road wheels could be substituted for the narrow-gauge trucks and the carriage could be towed by a traction engine. At the front of the carriage, there was a shear leg derrick that could be used to load and unload the gun for transport. The normal procedure was to transport the barrel and base on their own carriages on standard gauge rails until near the front and then transport both on narrow gauge rails or road wheels to the front. Site preparation consisted of creating a level piece of ground by laying a bed of stones and timbers then lowering the carriage onto the base plate. The base plate is prevented from moving by two anchors buried in front of the mount. The gun is then reassembled on the base plate and made ready for action. *Traverse and Elevation - The carriage employed a car traversing or ''berceau'' system where the car and trucks were placed on a base plate and could be traversed 7° left/right of the center line. The base plate is arranged with a pintle in front and the car has two rollers behind. At the rear of the rail carriage, there was a shell hoist and there was also a small cart which ran on rails to the breech for ammunition handling. The gun was loaded at +10° and could be elevated to a maximum of +40°. *Pros and Cons - Although adaptable the gun required considerable setup time.

World War I

The Canon de 240 TR Mle 1903 was assigned to units of the ALGP (''artillerie lourde à grande puissance'') during World War I. At first, they were organized in 4 groups of 2 batteries of 2 guns per battery. Later the guns were reorganized into 2 groups 1 with 3 batteries and 2 with 2 batteries of 3 guns with 1 spare. When the war ended there were 8 guns left in service.

Gallery

File:Canon de 240 Mle 1903-2.jpg, A schematic of the major gun components. File:Sur le front de la Somme. Transport de pièces lourdes par chemin de fer Decauville (15124305336).jpg, A barrel removed for transport on narrow gauge rails. File:Canon de 240 Mle 1903-3.jpg, A carriage placed on road wheels without gun. File:Popular science monthly (1872) (14802579093).jpg, Reassembling a gun onsite. File:Laden eines 24cm-Geschützes im Lager von Mailly.jpg, An assembled gun on wide gauge rails. File:Rohrseele_für_Kugelverschluss_155mm_R.Cie_Mle1907.JPG, The breech mechanism as used on a 155 mm gun.

References

{{DEFAULTSORT:Canon de 240 TR Mle 1903 240 mm artillery Artillery of France World War I artillery of France Railway guns World War I railway artillery of France World War I guns