Canon de 340 modèle 1893 à glissement

The Canon de 340 modèle 1893 à glissement was a French railway gun designed in 1916 that saw action during the First world war and Second world war. 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 Canon de 340 modèle 1893 à glissement started life as two Canon de 340/35 modèle 1893 naval guns as used on the Terrible class of coastal defense ships. The guns converted were made available when the Terrible class were deactivated and scrapped. The guns were typical built-up guns of the period with steel construction consisting of a rifled steel liner with several layers of reinforcing hoops and an interrupted screw breech. To load the gun barrel was lowered and a shell was brought forward by an elevated hoist on the rear of the carriage.