Canon de 240 L Mle 1884


The Canon de 240 mm L modèle 1884 was a heavy artillery piece originally employed as coastal artillery and later converted to siege artillery and railway artillery roles. Mle 1884 guns were used in both World War I and World War II.

History

The Canon de 240 mm L mle 1884 was one of a series of heavy artillery pieces designed by Colonel Charles Ragon de Bange. On 11 May 1874 three de Bange heavy cannons and two mortars were ordered by the French Army.
The mle 1884 was advanced for its time due to being built completely of steel instead of a steel liner and cast iron reinforcing hoops of the previous Canon de 240 mm C mle 1870-87. The mle 1884 was also breech loaded with a de Bange obturator and a simple hydraulic recoil system.

Variants

Coastal Artillery

In the coastal artillery role, the mle 1884 was mounted on a variety of barbettes which normally consisted of a large diameter geared steel ring set into a concrete slab behind a parapet. A rectangular steel firing platform sat on top of the ring with the barrel of the gun overhanging the parapet at the front and an overhanging loading platform to the rear. The firing platform was then traversed by a worm gear which attached to the base.
The recoil system for the mle 1884 consisted of a U shaped gun cradle which held the trunnioned barrel and a slightly inclined firing platform with hydraulic buffers. When the gun fired the hydraulic buffer slowed the recoil of the cradle which slid up a set of inclined rails on the firing platform and then returned to position by the combined action of the buffers and gravity. Later some mle 1884's were modified to use a Canet to reduce the number of crew needed to service the gun and increase its rate of fire. The resulting gun was designated the Canon de 240 TR mle 1884/03. At the outbreak of the First World War, it is estimated there were 149 mle 1884's deployed in coastal fortifications.

Siege Artillery

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, nor had they foreseen the growing importance of heavy artillery once the Western Front stagnated and trench warfare set in. Two sources of heavy artillery suitable for conversion to field use were coastal fortifications and surplus naval guns. Suitable field and rail carriages were built for these guns in an effort to give their forces the heavy field artillery needed to overcome trenches and hardened concrete fortifications.
Although an older design the need for heavy artillery on the Western Front was so pressing that at least five different mounts were devised for the mle 1884: two static and three railroad. The initial conversion of 16 guns was carried out by the Arsenal de Toulon and was designated the Canon de 240 mm mle 1884 sur affût à échantigolles. These consisted of the steel firing platform of the coastal gun being placed on top a platform made from wooden beams. There was no traverse mechanism so the entire platform had to be aligned with the target. Despite these limitations, the conversions were considered successful.
In 1915 St. Chamond was given the task of building a carriage for the mle 1884 and the design was accepted in 1916. The new gun was designated the Canon de 240 mm mle 1884 sur affût à Tracteur Saint-Chamont or Canon de 240 mm L modèle 1884 and St. Chamond completed sixty guns between October 1916 and October 1917. For transport, the mle 1884 could be broken down into two loads each with their own carriage. Each carriage was towed by an artillery tractor with the tractors consuming about of gasoline per. Therefore, the artillery tractors were only used near the front with long-distance transport accomplished by rail. Once onsite the guns could be assembled in approximately 24 hours by cranes and block & tackle.
The new mount used the same large diameter geared base as the coastal mount with 10° traverse and 38° elevation was possible. The new guns were popular due to good barrel wear, long range, and heavy shell. Guns that survived the war were designated the Canon de Mle 84/17 and used again during World War II. In 1939, twelve guns were mobilized and those captured by the Wehrmacht after the Fall of France were designated Kanone 556 and used for coastal defense.

Railway Artillery

In addition to its siege gun and coastal artillery roles, the mle 1884 was also converted to act as railway artillery: