Canon de 370 modèle 75/79 Glissement  The Canon de 370 modèle 75/79 Glissement was a French Railway gun designed during World War I but produced too late to see action during the war. The six guns built were held in reserve between the wars and were not mobilized by France during World War II. 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. 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. 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 engines 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. The mle 75/79 started life as "Canon de 370 modèle 1875/1879" naval guns which were the primary armament of the two Amiral Baudin-class ironclads of the French Navy. The guns were typical built-up guns of the period with several layers of steel reinforcing hoops. The guns used an interrupted screw breech and fired separate loading bagged charges and projectiles. To load the gun barrel was lowered and a shell was brought forward by an elevated hoist on the rear of the carriage. The guns consisted of a large rectangular steel base, which was suspended on two eight-axle articulated rail bogies manufactured by Schneider. The number of axles was determined by the weight limit for European railways of 17 tonnes per axle. The carriage was similar to that used by the contemporary Obusier de 520 modèle 1916 produced by Schneider. Since the carriage did not have a traversing mechanism it was aimed by drawing the guns across a section of curved track.