The Mortier de 370 modèle 1914 Filloux (MLE) was a siege mortar. It was designed before the First World War and was used during the war.

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Mortier de 370 modèle 1914 Filloux
A mle 1914 5 km (3 mi) behind the front lines near Proyart, France.
Type	Coastal artillery Siege artillery
Place of origin	France
Service history
Used by	France
Wars	World War I World War II
Production history
Designer	Louis Filloux
Designed	1908-1912
Manufacturer	Fonderie de Bourges [fr] Schneider St. Chamond
Produced	1914-1916
No. built	10+2 spares
Specifications
Mass	28.6 t (28.1 long tons; 31.5 short tons)
Barrel length	2.96 m (9 ft 9 in)[1]
Shell	Separate loading bagged charges and projectiles
Shell weight	400–540 kg (880–1,190 lb)
Caliber	370 mm (15 in)
Breech	Interrupted screw[1]
Recoil	Hydraulic recoil mechanism
Carriage	garrison mount
Elevation	+6° to +65°
Traverse	12°
Rate of fire	1 shot every three minutes
Muzzle velocity	290–318 m/s (950–1,040 ft/s)
Maximum firing range	10.5 km (6.5 mi)[1]

Close

Although the majority of combatants had heavy field artillery prior to the outbreak of WWI, 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. Since aircraft of the period could not carry large 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.^[1]

However, a paradox faced artillery designers; 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 disassembled into multiple loads light enough to be towed by a horse team or traction engines and then reassembled before use. Building a new gun could address the problem of disassembly, transport and reassembly, but 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 weight, mobility and setup time were addressed.^[1]

The MLE was designed between 1908 and 1912 by French artillery officer Louis Filloux. The barrels were converted from surplus 340 mm (13 in) naval guns that were shortened and bored out to 370 mm (15 in). The guns were typical built-up guns with layers of steel reinforcing hoops. The guns used an interrupted screw breech and fired separate loading bagged charges and projectiles. During loading the barrel was lowered 6° and a shell was brought forward by a cart^[5] that ran on a rail to the breech of the mortar. A crane was used to lift projectiles onto the cart.^[2] Ten mortars and two spare barrels were ordered in November 1914 and built under the designer's supervision. Deliveries began in May 1915 and continued until January 1916.^[6]

The mortars fired separate loading bagged charges that weighed up to 82 kg (181 lb) and projectiles that weighed between 400–540 kg (880–1,190 lb). As the war progressed heavier projectiles were manufactured including armor-piercing and high explosive.^[9]

• A mle 1914 being transported on a narrow gauge railway.
• 370 mm Filloux mortar mounting details.
• A mle 1914 being positioned during the Somme Offensive 15 September 1916 Aisne Area, France.
• A mle 1914 being fired from a gully known as "La Baraquette" during the Somme Offensive 16 September 1916.