Canon de 75 antiaérien mle 1913-1917

The Canon de 75 antiaérien mle 1913-1917 were a family of French 75 mm anti-aircraft guns designed and manufactured by Schneider et Cie at Le Creusot. These guns were used by the French Army during the First World War and Second World War.

History
The origins of the modèle 1913-1917 go back to the Canon de 75 modèle 1897 field gun which was first employed on improvised anti-aircraft mounts, which were typically earthen embankments or scaffolds to get the muzzle pointed skyward. Later in the war specialized anti-aircraft mounts were developed.

These included:
 * Canon de 75 mm antiaérien mle 1913 - a self-propelled version, on the back of a De Dion-Bouton truck chassis.
 * Canon de 75 mm antiaérien mle 1915 - a pit mounted high-angle steel girder framework with 360° traverse. There was also a version with a rotating platform mounted on a concrete pedestal.
 * Canon de 75 mm antiaérien mle 1917 - a single-axle towed version with three outriggers. This had all fire-control equipment mounted on the carriage and was a Schneider design.

The most common anti-aircraft configuration was a fixed battery of four mle 1915 guns located near major cities, factories or military bases. Target range was measured by optical coincidence rangefinders and height by optical height finders which measured the distance to the target and the elevation angle, which together gave the height of the aircraft. These coordinates were transmitted to a single Brocq fire-control station, which was an electric tachymetric device that calculated target speed, altitude and direction to determine deflection angles. These calculations were then transmitted to displays on each gun for the crew to aim at for barrage fire. The guns themselves had only simple sights and lacked the ability to engage individual targets.

Anti-aircraft effectiveness during the First World War was poor, but many of these systems remained in use without upgrades until the Second World War. By which time they were nearly useless against faster, higher flying targets. During the late 1920s it was realized that the mle 1897 was outmoded as an anti-aircraft weapon and development of a new gun barrel was begun in 1928. The goals of the rearmament program were faster rate of fire, higher muzzle velocity, increased vertical range, modern fire control and greater mobility with new gun carriages. However the priority for armaments at that time was the construction of the Maginot Line fortifications and work progressed at a slow pace. This slow pace and lack of funds meant all three anti-aircraft versions of the mle 1897 were still in use in large numbers when World War II began in 1939. It is estimated that 913 mle 1897 anti-aircraft guns were still in service in 1940.

Modernizations
Some of the first guns to be upgraded were the fixed emplacements around high priority targets such as Paris. These mle 1915 guns had their barrels replaced with new 53 caliber barrels built by Schneider. Likewise some mle 1913 self-propelled guns and towed mle 1917 guns also had their barrels replaced to produce the Canon de 75 mm contre aéronefs mle 17/34. Large numbers of 75 mm guns were captured by Germany after the French defeat in 1940.

Guns in German service were given the designations:
 * 7.5 cm FK 97(f) - These were un-modernized mle 1897 guns. Some were sold to Axis satellites, some were converted to 7.5 cm Pak 97/38 anti-tank guns and others were integrated into Atlantic Wall defenses.
 * 7.5 cm Flak M.17/34(f) - These were modernized mle 17/34 guns that remained in German service as anti-aircraft guns.