Canon of 75 Mdle 1897
Country:France
Caliber:75mm
tube length:2.58m
weight:1,140 kg
curb weight:1,970 kg
initial projectile speed:575m/s
horizontal fields of fire:6°
vertical field of fire:-11° to +18°
range:11,000m
projectile weight:6.195 kg
The 75 mm model 1897 gun is a field artillery piece of the French army, which is one of the most famous guns of all time. Of a revolutionary design for its time, it brings together, in fact, all the latest improvements in artillery at the end of the 19th century, namely:the use of smokeless powder, cartridge ammunition, fusing shell, loading by the breech according to the Nordenfelt process, and a hydropneumatic recoil brake. This synthesis, by eliminating the effects of recoil, finally made possible an old gunner's dream, rapid fire.
Having become an emblem of French military power, soon known as the seventy-five, or even our glorious seventy-five, it is the object of worship on the part of French soldiers and patriots, who see in it a miracle solution to any problem. . This enthusiasm will lead to the neglect, among other things, of the modernization of heavy artillery, an error that will be hard paid for during the First World War. Indeed if the 75 is the best field gun of the time, it is much less comfortable and useful in a war of position, where one needs heavy artillery, to reach the entrenched troops. He will nevertheless distinguish himself in a glorious way, but largely thanks to his servants who will pay a heavy price. Still in service in large numbers in the French army in 1940, it proved to be overwhelmed this time in mobile warfare, because it had been delayed in making it suitable for automobile traction, which was now necessary. However, it will experience a second youth as an anti-tank gun, in the hands of the Wehrmacht and the Free French forces.
Birth
In September 1892, an experimental 52 mm caliber rapid-fire cannon, designed by Captain Sainte-Claire Deville, was tested at the Bourges arsenal. General Mathieu, director of artillery, asks Commander Deport, polytechnician and artillery officer, who directs the Puteaux workshops, to undertake the production of an enlarged version with a caliber of 75 millimeters. The project takes the designation of 75C. At the same time, two other projects were launched, mainly intended to mislead German intelligence, 75A and 75B. A first test firing of the 75C was carried out at the beginning of 1893, but there were still problems with the tightness and reliability of the recoil brake. It will be the same during the shootings of November 25, 1893 and May 19, 1894, nevertheless after the second, the Minister of War, General Mercier, decides to order 340 guns. In November 1894, Deport discouraged, decided to retire, and was replaced by Sainte-Claire Deville, who was assisted by Captain Rimailho. He decides to completely overhaul the brake, but using the steel blocks ordered for the manufacture of those of the first model; three years of study will be necessary to arrive at a satisfactory result, brake II. It also widens the scope of the study, by including everything that is necessary for the service of the piece, that is to say in particular the problem of an efficient supply of ammunition, made essential by the high rate of fire. General Langlois also ordered him to provide for the use of fusing fire, by modifying the device for unblocking the vents, which he had made for his 52 gun.
To solve the supply problem, Sainte-Claire Deville broke with the use of artillery, which until then placed its ammunition boxes well behind the guns. He designed a fore-end box, which overturned right next to the gun, thus reducing the fatigue of the outfitters, who no longer had to transport the shells over several meters to feed the guns. The tilting of the box elegantly solves both the problem of transporting the cartridges, which transported horizontally, would risk undergoing unacceptable deformations, but also provides the providers with shelter, because during firing they are covered by the bottom of the box and its doors, and can relatively protected, extract and prepare the shells for the rest of the firing team. At the level, several innovations, in addition to the recoil brake, are implemented, to allow rapid firing, to immobilize the piece, the two wheels are equipped with a drop brake, whose pads are interposed between the ground and the tread, plus a spade on the back of the arrow, sinks into the ground, on the first shot.
In December 1896, the tests of the new piece proved to be extremely conclusive:ten thousand rounds were fired at a rate of twenty rounds per minute, without incident. An order of six hundred copies was therefore launched for 1897. The production of each element of the 75 was carried out in two associated factories, a measure advocated by Deville, to promote better interchangeability of spare parts. The guns are manufactured in Bourges and Tarbes, the carriages in Tarbes and Tulle, the boxes in Saint-Étienne and Châtellerault, and the slides and brakes in Puteaux and Saint-Étienne. An armaments commission, created in December 1897 and headed by General Gras, was responsible for coordinating and controlling manufacturing. The gun officially entered service in the French army on March 28, 1898, and was presented to the public for the first time on July 14, 1899, during the parade on the Champs Élysées. In the meantime, to continue to deceive Germany, General Deloye, Mathieu's successor, continued the tests of the 75A and 75B, going so far as to suggest that the 75B might be adopted. This disinformation enterprise, in the context of the Dreyfus affair, bore fruit:the Kaiser's army in fact precipitously adopted, in 1896, a model of 77 mm gun, with a rigid mounting, completely outdated compared to the 1897 model. , and did not pursue studies on a similar piece, presented by Conrad Haussner, in 1891, which suffered from the same problems as the first French brakes.
Description
The weapon system making up the 75 mm model 1897 equipment is made up of three rolling elements, the barrel, the front end and the rear end-box, which combine to give two types of attachment:the car -gun and the car-box. As is traditional in French artillery since the Vallière system, elements such as wheels are interchangeable. Three types of wheels will also be produced:wheel n°7, reinforced wheel n°7 and reinforced wheel n°7C, the first two consist of seven wooden rims connected to the hubs, also by fourteen wooden spokes. The hub engages on the axle stub, via a bronze bushing. The reinforced wheel is provided with metal shoes which reinforce the connection between the spokes and the rims, and with a metal circle which reinforces the circumference of the rims, as for the 7C wheel, it only has two rims for simplification. in curved wood.
The cannon
The barrel itself consists of a single steel tube, reinforced at the rear by a cylinder head sleeve, it is 2.72 meters long and provided with twenty-four grooves with constant pitch to the right and deep of 0.5 millimeters, over a length of 2.23 meters. It rests on a bronze jacket which serves as a carriage during recoil. It is closed at the rear by a Nordenfeld-type eccentric screw breech block. This element allows a very fast and safe firing, the opening and the closing of the breech, is done by a simple movement of about 120° of the crank handle, which closed the chamber, by a rotation of the screw- breech, the tightness of which was also ensured by the brass casing of the shell. As the striker was only in front of the socket primer when the breech was fully locked, any premature action on the fire pull cord could not trigger the shot, making the operation very safe. After the shot, the opening of the breech activated a mechanism for extracting the casing, which is pulled by its rear rim.
The barrel is only connected to the carriage by the firing brake device, the trunnions of the latter rest on the flanges, and to the barrel by a rod. The principle of long recoil is quite simple in principle, but it was difficult to develop and make reliable, with the technologies of the time. The Deport type I brake and the Sainte-Claire Deville type II brake, although they differ little in principle, are markedly different in their construction. Rather than a spring, the compression of an enclosed volume of air is used to obtain the recovery of the energy of the recoil and the return to battery thanks to it. The barrel-holder rod has a piston at its rear which pushes on the oil contained in the upper tube, and forces that to pass through a vent in the lower tube, where it pushes back the free piston which separates it from compressed air. The kinetic energy of the recoil and the force exerted by the compressed air are thus gradually balanced, gently damping the movement of the barrel. This once stopped, the air relaxes again pushing the oil and therefore the barrel. In total, the mobile assembly, weighing 461 kilograms, moves back a length of between 1.14 and 1.22 meters.
The gun carriage is made up of an arrow made up of two flanges, held together by spacers, all in heavy sheet steel, the assembly is streamlined on the top by a thinner sheet, which includes a cushion, on which rests the barrel brake, in the road position. On the flanges are fixed the two axle covers, the butt spade and two butt handles. On the two axle covers, are fixed the tubular axle whose two conical ends engage in the wheel hubs, but also the two independent steel shields, which protect the servants on the battlefield, the one on the left is reinforced by a flying buttress which fixes it to the flange. In 1909, the shields having proved to be too fragile in the field, their arrangement will be modified, the buttress is moved to the right shield, and a removable crosspiece connects them above the barrel, as well as angles below.
Below the arrow, we find the mechanism that is used to set up the wheel brake, when firing, the rigid assembly of the two pads, when unlocked, descends to the ground, behind the wheels, pivoting around the axle. A slide comes to block the rod at the back of the assembly, during the setting in battery by the servants who raise the butt of the barrel. The two wheels are then forced to mount on the runners and the part then rests on three fixed points, the two runners and the butt spade. The latter sinks into the ground during the first shot, the barrel moving back about ten centimeters, thereafter it becomes almost completely immobile, during the following shots, which allows the servants to remain in its immediate vicinity.
The front end
It consists of an axle, a track of 1.51 meters, carrying a chest where are housed vertically in four groups of cells, 72 shells. it weighs 774 kilograms when loaded with high-explosive shells, and 830 when loaded with bullet shells. It is surmounted by a bench seat for two servants and extended by a 2.7 meter drawbar to which are hitched six, or sometimes four draft horses. When placing a piece in battery, the front end of a gun is placed to the left of the piece and reversed, to give easy access to the ammunition which is found horizontally. The rocket knockout device is fixed in the center of the ammunition chest. This high-precision mechanical assembly makes it possible to precisely and quickly adjust the combustion time of the 22/31 delay fuzes of the bullet shells. Timing adjustment is achieved by a cut made in the rocket's spiral powder wick, so the device includes a blade holder operated by a lever, and a set of gears that converts the desired distance into blade position on the rocket, all in double to speed up the maneuver. Subsequently a modified model, with two graduations, will be introduced allowing the 22/31A fuzes to be adjusted as well, which have a maximum delay of 31 seconds instead of 24.
The box rear end
This trailer, which attaches to the same limber as the gun, carries 48 additional shells, for a total of 72 shells for each box car. Each piece is accompanied by its box, which gives it a total of 120 moves available. furthermore, each battery of four pieces, has eight additional caisson cars, which are divided between the 5th, 6th and 7th pieces of the battery, making a total of 1248 shells for the battery or 312 for each piece. In combat, the first four so-called firing pieces, i.e. a cannon car and a box car, as well as the fifth, with two box cars, deploy on the firing position. The two other pieces of each three caisson cars, are placed four or five hundred meters behind, in a sheltered position, to constitute the combat level. They are accompanied by an eighth piece, which includes a forge car and the battery van. The ninth battery piece, which includes three food vans and a fodder car, is generally assigned to the regimental train, to free the battery leaders from supply duties.
Sights and accessories
Ammunition
The ammunition used by the 75 model 1897, is of the cartridge type, that is to say that the shell is crimped on a brass casing, which contains the propellant charge, which allows the rapid loading of the shot, but which ensures, by its base, also the perfect tightness of the barrel when firing. The propellant mixture used is powder B (after the name of General Boulanger), developed in 1884 by the chemist Paul Vieille. It is smokeless which allows rapid firing, black powder would make rapid firing impossible due to fumes given off and fouling of the tube, but its lack of stability in hot climates will force engineers to paint the material in a light color, blue gray will be adopted instead of the usual olive green. Subsequently, the powder department will improve the mixture by adding a small amount of diphenylamine. Three types of charges are available, the normal charge, the reduced one which allows more plunging shots and less fatigue on the material, and the special decoppering charges, which contain small amounts of lead and tin, to clean the scratches of the tube , remnants of copper left by the shells. The three types of charges are distinguished by the marking of the muzzle velocity obtained on the cartridge.
Two main types of shells are mounted on the cartridges, the explosive shells and those with balls, commonly called shrapnel. The first high-explosive shell, the Model 1897 high-explosive shell, had a strong steel wall and a small amount of explosive charge (170 grams of black powder). It is fitted with a DE 22/31 double-effect fuze, which explodes on contact or with a maximum delay of 24 seconds. Its evolution, will give the 1900 model, with a thinner wall, weighing only 5.4 kilograms, but loaded with 695 grams of melinite, the use of which requires the use of a powdered melinite relay detonator. It also uses new types of fuzes which explode on or after impact, the 24/31 percussive series (model 1899, model 1899/1915, model 1914 and model 1916), to give it effectiveness against the fortifications. Some of the 1900 type shells are also provided with a smoke mixture, to facilitate firing adjustment. An aerodynamic braking device, a simple plate attaching to the tip of the warhead, will also be used, to give more curvature to the trajectory and achieve hidden objectives, but its use affected the accuracy of the shot. At the end of the war, General Dessaleux's 1917 and 1918 types appeared, which, with better profile, reached ranges of around eleven kilometres.
The bullet shells are also two types M and A. The M, of 1897, said to be mixed charge, contains 440 grams of black powder and 290 spherical bullets of twelve grams, in lead hardened with antimony, the whole surrounded thin steel walls. It will be practically supplanted by type A, or rear charge, where the lighter powder charge (110 grams), instead of being mixed with steel balls, is grouped at the rear of the shell. The 261 balls were then projected towards the ground, more effectively than with the M model. These two shells were subsequently modified for anti-aircraft use, the M shell giving the modified M 1911, the A becoming the A modified 1917, which used a delay fuze of up to forty seconds. Other shells will be designed during the war, the smoke shell of 1915, which contains in the body of the explosive shell, a composition based on phosphorus producing a thick cloud of smoke, for a few minutes, after its detonation, the 1916 illuminating shell, based on the bullet shell, including the DE 22/31 fuze, caused the ejection of an illuminating cartridge and its parachute, which then illuminated the battlefield for about forty seconds. The same year appeared the incendiary shell type G, which contained in the body of the ball shell M, six bags filled with a mixture of tarred rope and phosphorus, all ignited by a small quantity of black powder and a Model 1914 instantaneous fuse. Even more infamous are the poisonous shells, based on the high-explosive shell, but with only enough charge to rip open the wall and let the gas escape. Also in 1916, the engineer André Lefèvre, developed an armor-piercing shell, known as AL, which was made of very thick steel cast iron and loaded with 285 grams of TNT, ignited by a 24/31 Schneider 1916 rocket, weighing 7 .2 kilograms, it could reach the range of 9500 meters.
Part service
In addition to the gun chief who directs the operations, a team of six servants is necessary to use the gun to the maximum of its possibilities. When shooting, the team is distributed as follows:
* the shooter sits on a seat on the right, facing the gun, he is responsible for opening and closing the breech and firing, but also for changes of sight.
* the pointer seated on the left, takes care of pointing in elevation and drift.
* the loader behind the pointer, engages the cartridge in the chamber.
* behind the box, three other men work, two providers who supply the unblocker device with shells, the unblocker, then pierces the vents of the fuzes then transmits the prepared shell to the loader.
A well-trained team of gunners manages to fire up to 28 shots in one minute, but such a rate cannot be maintained for very long, due to the need to restock shells, but also to the fatigue generated and the overheating of the tube, in practice the sustained rate is more like six strokes per minute. If the firing is to continue, the ammunition in the front train trunk is first used, then that contained in the box attached to the gun, then the box cars return to the combat echelon, which directs them to the depot. army corps, to be reloaded there, and sends one of the caisson cars, which it has, to supply the piece. During a long firing phase, a noria is then established, which supplies the firing battery from the army corps depot, which is located a few kilometers behind.
To load the barrel, it was enough to open the rotary breech and insert the cartridge, then close the breech with a quick movement of the wrist. After firing, the recoil of the barrel did not drive the carriage back as in older models. The carriage of the 75 remained in place, but the tube of the barrel itself moved back into its housing at a distance of 1.20 m, then slid back to its initial position thanks to a hydraulic detent system. When the tube came back in place, all you had to do was open the breech, which automatically ejected the empty cartridge, then place another one inside.
The military advantages of this new gun were obvious. The gunners did not need to jump back when firing the cannon, as they had to when the carriage moved. As a result, they could load the gun more quickly, which otherwise remained in position, which avoided having to readjust the target with each shot. The 75 gun had a rate of about 6 rounds per minute with a range of 11 km. In critical situations, it could fire up to 20 rounds per minute.
Variants
One of the first derivatives of the 1897 model, the 75 De Dion Bouton auto gun model 1913, intended for defense against aircraft in the armies, is an extremely innovative model, with its gun on the platform of a truck, which can pivot on any the azimuth. However, it turns out to be ill-suited, due to a low pointing speed, the absence of suitable ammunition, and its cost. Only one specimen existed at the start of the war, but groups of autocannons were formed in 1916. In 1918, four hundred of them, ensured the defense of the French lines against the German air force, they were organized within five anti-aircraft artillery regiments, the 63rd, 64th, 65th, 66th and 166th, which each had four batteries of four autocannons, two companies of searchlights and one of protection balloons. They will be modified in 1934, by the assembly of a central post of direct fire, and will remain in service, for lack of anything better, during the Second World War, 236 of them still serving in March 1940. For the protection of the rear areas , within the air defense of the territory, another type of equipment is put into service, the 75 mm model 1897 on a model 1915 platform, this fixed part can be deployed in twenty-four hours, the platform allows the tube to be pointed from 0 to 75° in elevation and over an azimuth of 360°. During the 1930s, the speed of aircraft having become too high, these mountings were replaced by lighter 1939 model platforms. In April 1940, only twenty of them remained on the 1915 model platform, and fifteen on the 1939 model platform.
To rejuvenate the 75 in its role as a field gun, between the two wars, the French army tried to adapt it to automobile traction, which began to supplant horse-drawn vehicles during the 1930s. suspension and the wooden wheels, indeed limit its speed of movement to about eight kilometers per hour, beyond that, the vibrations risk damaging the part. After a proposal from André Citroën, who proposes a carrier train which is placed under the barrel, during transport, we decide to modify the part itself by modifying the running gear, two new versions of the 75 appear:
* Equipment of 75 model 1897 modified 1938, modification to adapt the 1897 model, to automobile traction, by replacing the original wheels with molded wheels with solid tyres, the felling brake is retained and the increase in mass to 1.5 tons, makes maneuvering the piece more difficult, there were about seven hundred copies modified in this way, some will be equipped with stamped rims and inner tube tires.
* Equipment of 75 model 1897 modified 1938-1940, improvement of the precedent, with pneumatic tires, and the felling brake replaced by drum brakes in the wheels.
In service
Units equipped with 75 model 1897
In 1897, when the piece entered service, the French army fielded forty field artillery regiments, the most recent of which were created in 1894. Subsequently, the adoption of the three-year national service, their number goes to sixty two. They are divided into three types, the regiments assigned to the army corps with four groups of batteries, twenty in number, and those assigned to the divisions which are with three groups, except ten which have in addition a fourth group called on horseback, which is to be detached from the cavalry division. Each group includes three batteries, making a total of 648 four-piece batteries.
The regimental staff comprises seventeen men, including three officers and three reserve officers, with thirteen horses, eleven of which are saddles, a van and two bicycles. The group staff is even larger with twenty-one men, including six officers, it brings together specialists as diverse as the medical officer and the veterinary officer, but also the butcher. It is equipped with a medical car, a meat car, two baggage wagons and fifteen horses, eight of which are saddles. In normal times, its personnel are assigned to the ninth piece of the first battery of the group, but in wartime, the whole is grouped in the regimental train.
The battery is the elementary unit of the French artillery, the adoption of the 1897 model, causes its reduction, because of the rate of fire, from six to four guns. This organization became official by a ministerial ordinance in 1899, then was fixed by the law of July 24, 1909. Its total staff was three officers and one hundred and sixty-eight men. The equipment includes sixteen cars, including four guns, twelve caissons, plus a forge and four vans. One hundred and sixty-eight horses, including thirty-six saddle horses, ensure its mobility. It is subdivided into nine gun platoons, commanded by a quartermaster, assisted by one or two brigadiers. In combat, the first five form the firing battery, commanded by the active lieutenant, the last four form the combat echelon led by the reserve second lieutenant, however the ninth is most of the time grouped with that of the other batteries, within the regimental train. The thirty mounted batteries, differ little with a staff of four officers and one hundred and seventy-five men, however to increase mobility most of the servants are mounted on saddle horses, there are therefore two hundred and five horses, of which eighty-two, in this type of battery.
First actions
The 75 model 1897 material was used for the first time in operations, in June 1900, during the international expedition against the Boxers. Three batteries were employed, particularly during the capture of Peking on August 13, where their efficiency impressed Field Marshal Von Waldersee, commanding the expeditionary force, who hastened to report to his government the superiority of the new gun. French artillery.
Later, in 1912, Serbia, Greece and Bulgaria, which bought the French cannon, first opposed the Turks, during the First Balkan War. The Turkish army is equipped with German 77 mm guns, which are clearly inferior. The Second Balkan War saw 75 mm fire against each other, with Bulgaria turning against its former allies.
In action during the First World War
France enters the war with four thousand 75mm guns at its disposal. Despite their lower effectiveness in the context of trench warfare, they nevertheless played a decisive role during the war, contributing in particular to stopping the Germans during the Battle of the Marne in 1914, and at Verdun in 1916. They are served by crews of very high competence, a good part of the artillery officers having come out of great schools like Polytechnique. They are one of the main weapons of the French army and no less than 17,500 guns were built during the war, the ammunition being produced at more than two hundred million units. The consumption of 75 shells became disproportionate:for example, no less than 3.75 million of them were fired during the month of March 1916 alone in Verdun.
France went through a serious crisis at the end of 1914 when the production and the stocks of shells, however important, proved to be insufficient. It was then decided to resort to private industry, in order to increase daily production from twenty to one hundred thousand shells. Many civilian industries are being converted, and thanks to female labor and the use of new manufacturing processes, such as making shells by machining rather than forging, production is increasing rapidly. En septembre 1914, onze mille obus sont produits, on passe à quarante six mille au début de 1915, puis à soixante quinze mille en juin de la même année. Mais, en conséquence, la qualité des munitions décline, provoquant plus souvent des éclatements et des gonflements du tube de l’arme (1 éclatement tous les 3 000 tirs en moyenne, contre 1 tout les 500 000 en 1914). La situation est telle que le commandement finit par ordonner de n’utiliser les 75 mm qu’en dernier recours Devenu colonel, Sainte-Claire Deville est chargé du problème et réussit dès septembre 1915 à redresser les standards de production, grâce à des contrôles plus stricts. Toutefois, la qualité n’atteint plus jamais celle d’avant-guerre.
En action pendant la Seconde Guerre mondiale
Encore en service durant la Seconde Guerre mondiale, il s’illustre lors de la bataille d’El Alamein. Lors de la Bataille de Bir Hakeim, en juin 1942, les canons de 75 de la brigade des français libres, servis par le le 1er RAFFL, sont un outil efficace de la défense de l’oasis. Les forces de l’Axe perdent 51 chars et une centaine de véhicules, pour une bonne partie à cause des 75.