SOME FRENCH FUZES

Version francophone


French time fuse, 'type 22/31 modèle 1897', mounted on a shrapnel 75 mm shell head
Main charcteristics of French fuzes

PERCUSSION FUZES
Percussion fuze 25 Mle 1859(Desmarest)
Percussion fuze 25/38 Mle 1874 (Henriet)
Percussion fuze 25/38 Mle 1875 (Budin)
Percussion fuze for 37 mm and de 47 mm shells Mle 1877(Desmarest)
Percussion fuze SM 25/38, 30/45 and 40/55 Mle 1878, 1878-81 and -92(Siège et Montagne)
Percussion fuze 24/31 Mle 1899 and 1899-08 (Robin-Lejay)
Percussion fuze 24/31 Mle 1899-15 (Robin)
Percussion fuze Mle 1915 for 105 mm Schneider shells (Schneider)
Percussion fuze 24/31 Mle 1916 (Schneider)
Percussion fuze 24/31 Mle 1916 for trench mortar(Peuch-Remondy)

INSTANT EFFECT FUZES
Percussion fuze I 24/31 Mle 1914 (Peuch)
Percussion fuze I 22/31 Mle 1915 (Peuch) for Naud shell
Percussion fuse I.T. 24 Mle 1915 for trench mortar
Percussion fuze I.A. 24/31 Mle 1915 and I.A.L. Mle 1916 (Lefèvre)
Percussion fuze T.C.A.L. 34/31 Mle 1917 and Mle 1918 (Lefèvre)
Percussion fuze RY 24/31 Mle 1917 (Remondy)
Percussion fuze RYG 24/31 Mle 1918 (Remondy-Gaba)
Percussion fuse I.T.R. 24 shortened Mle 1918 for trench mortar(Remondy)

TIME, OR TIME AND PERCUSSION FUZES
Time and percussion field fuze 25/38 Mle 1880 (Budin)
Time and percussion siege fuze 40/55 Mle 1880, 25/38 Mle 1881 and 30/55 Mle 1882 (Siège et Montagne)
Time and percussion field fuze 25/38 Mle 1880/85 (Budin)
Time and percussion siege fuze 25/38 Mle 1881/85 (Siège et Montagne)
Time and percussion field fuze 30/38 Mle 1884 and 1884 T (Saussier)
Time and percussion fuze 30/55 Mle 1889 et 1889 T or 30/55 Time fuze Mle 1913 (Saussier)
Time and percussion fuze 40/55 Mle 1880/93 (Siège et Montagne)
Time and percussion or time fuze 22/31 Mle 1897 or 1916 (Saussier)
Time and percussion or time fuze 24/31 Mle 1915 or 1916 (Robin)
Time and percussion or time elongated fuze 24/31 A Mle 1916 or 1918 (Robin)
Time and percussion or time long distance fuze 24/31 LD 1917 or 1918 (Robin)
Time and percussion or time increased long distance fuze 24/31 LDA 1918 (Robin)
Double rings time and percussion fuze St Chamond



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French fuses

Fusée Scnheider

Humiliated by its quick defeat against Germany in 1870 in which one of France weaknesses proved to be its obsolete artillery technique and tactics, the French Army dedicated much energy of its best technicians to to develop these weapons and ammunitions. The end of the XIXth century was the time for a remarkable technological evolutionnof this 'science', both in the guns and in the shells and fuzes technologies, in all the geopolitical powers that were all wanting to get better weapons than their potential future enemies for the next war. The ultimate modernization wave before 1914 mainly concerned the consequence of the appearance in 1987 of the famous '75' French gun, outclassing so much its competitors that it became a world reference and induced all the other countries to enter a modernization race.

In France the elites of the time could not resist to the tentation to consider this new weapon suitable for most the missions of a modern war. The spirits were clearly in the mood of rationalisation and optimization of the resources. It is a possible and personnal clue to understand the French fuzes history : comparatively to the profusion of the German models, there were relatively less French fuzes families in use during WW1, with often similar shapes and with factory-modulable properties (for instance addition of a detonator to adapt to the TNT loaded shells, or of a small compressed gunpowder piece retarding the burst with some hundredth of a second).

Their relative polyvalence can make the French fuzes classification sometimes uneasy. For instance :

  • many of the percussion fuzes designed after 1914 were designed to be 'instant effect' fuzes and were tranformed into normal percussion fuzes (delayed or not) by addition of a small delays in the pyrotechnics by the factory
  • some fuzes designed for the classical artillery were also used with the trench artillery

For this reason, the choice has been made to include in the instant effect fuzes of this study only the ones that allowed a real 'premature' explosion over the ground surface, and keep the other 'instant effect' fuzes having optionnal 'percussion' or 'delayed percussion' variants in the 'percussion fuzes section'. Also, we did not try to separate the trench artillery fuzes from the artillery fuzes.

Another French fuzes characteristic concerns the time and tima and percussion fuzes : France was the only country to prefer almost exclusively the tubular spiral type fuzes , while all other countries adopted the rotating discs types.

French WW1 fuzes models also differentiate themselves from some the other countries' ones by their relative simplicity and their low mass. Finally, compared to German fuzes, French ones are entirely made in noble metals (brass), proving this nation remained well delivered with minerals and metals by its allies and colonies throughout the war.

For this latter reason, the French fuzes that can be found nowadays on battlefields or in collections are often less impressive by their mass than most of the other nations ones, but often in relative better condition, being less corroded than the German fuzes using more and more cheap material with the maritime blocus going on.

One final - and potentially lethal - characteristic of the French fuzes is the presence, for the ones designed after the introduction of modern high explosive shells replacing gunpowder shells, of a screwed or sometimes integrated small detonator at the end of the tail, filled with a small quantity of unstable explosive stuff. They were to provoke the detonation of a bigger primer inserted in the shell. These small detonators are sometimes still attached on the fuze that can be observed in ancient battlefields and remain dangerous even after more than 100 years.

The French fuzes denominations are simple and relatively well normalized, indicating most of the time the available function and properties, the external diameter of the fuze at the junction with the shell, the one of the tail thread, the year of the design and/or revision, and often the name of the designer (person or company).



The fuzes pictured below to illustrate that page are inert and have been observed in museums or private commections. They are not coming from battlefileds diggings and have not been manipulated.

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Percussion fuses


Desmarest percussion fuze Mle 1859
25 mm percussion fuze without detonator Mle 1859 System Desmarest

The presence in this section of this rudimentary fuze that was not in use in WW1 only makes sense because it gives a good starting point for the story of the French percussion fuzes used during WW1. Appearing in 1859, the Desmarest percussion fuze was mounted on the 4, 8 and 12 shells that were shot during the 1870 short war opposing France and Germany.

It survived this war, as models dated from the following years of the same decade can be found, but was then replaced by the many successive models that abounded afterwards.

This fuze was indeed a rather primitive direct action fuze. The brass body was composed with an hexagonal head and a 25mm diameter threaded tail whose back wall was bored with a communication vent to the shell's inside. A primer was placed inside the cylindric room bored into the fuze, held inside a wooden piece fixed against the lower wall of the tail. At the opposite side a wooden plug was closing the fuze hexagonal head, and was bearing in the iside a protuding static percussion pin aiming the distant primer. These two wooden pieces were simply fixed by nails and screws trhough the brass body.

At the impact on a solid target, the fuze top wooden plug was pushed back to the inside and the percussion pin hit the static primer, triggering the flame communicated to the shell body through the vent. This design was accompanied by weaknesses : particularly, this kind of fuze was often failing when penetrating into too soft targets, or when the contact with a stiff target was not perpendicular enough.

Astonishly, this latter weakness was sometimes converted into an asset by a quite random shooting texchnique : a tangent trajectory was searched, provoking the shell bounce on the target while the friction heat was hoped enough to trigger the fuze primer ignition so that the shell could explose in flight after the rebound, with an antipersonnel effect. ..

This fuze only safety was a thin steel plate protecting the top wooden plug and attached to it by two little nails. It had to be removed before use.

5 variants of this fuze with different thread diameters were existing for the use with the shells in service : 20, 22, 25, 30 and 31 mm.


22 mm Desmarest fuze. The profile looks like a simple nutscrew with hexagonal head. This item is dated 1875.
22 mm Desmarest fuze. This view shows the cylindric central room, the top wood plug is missing.
22 mm Desmarest fuze. Top view : there are some wood remains inside the fuze body.
22 mm Desmarest fuze. Rear view with the central vent communicating the flame to the shell, and the two holes for the screws attaching the inner wood piece bearing the primer.
22 mm Desmarest fuze. Rear view, notice the lateral hole inside the hexagonal head for the nail fixing the top wooden plug.
Desmarest fuze. Vintage scheme.



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25/38 Henriet fuze Mle 1874/75
25/38 mm percussion fuze without detonator System Henriet, modèle 1874/75

During the last XIXth century decades, the artillery was subject of a very quick technological evolution applied also to the ammunitions and fuzes. In France, after the very rudimentary direct action fuzes came the very first inertia percussion mechanism fuzes such as the Tardy (1860), Double Réaction (1865), Friction Tardy (1870) and Maucourant (1876) systems.

The frustration created by the France's defeat in 1870 against Germany galvanized the minds and amplified the innovations even further. In 1874 the Explosives section Chief Henriet from the Ecole de Pyrotechnie has his new 'mixte' revolutionary time and percussion fully brass fuze ('fusée mixte Henriet de 30mm Mle 1874')adopted. This was to be the mother of most of the following percussion fuzes in France for the following decades.

While tye time system was still similar to antique systems with its linear fuzing tube (but with an touch of innovation with the presence of a concussion system to ignite it), the percussion system was keeping very little of the preceeding systems and introduced safety mechanisms based on a safety spring and brasse plades (staple).

The percussion-only version of this fuze, the Fusée percutante de 25/38 mm Système Henriet, modèle 1874 et 1874/75 was keeping the same inner architecture but without the time system organs (fuzing tube and concussion system), had a 25mm diamteter threaded tail and a 38mm lower diameter head cone.

The percussion mechanism was located inside a cylindrical room parallel to the body axis. It was composed of a static primer block fixed to a large metallic head screw, and a mobile inertia block bearing the percussion pin. A double safety system was integrated :

  • a thin soft metal membrane was covering the primer and could only be pierced by the percussion pin when this latter was propulsed by a sufficient energy. This system was inherited from the first French inertia percussion fuzes.
  • the percussion pin could slide inside the hollow mobile graze pellet (inertia block) and its tip was hidden at rest inside this room, kept in this position by a safety spring. This spring could only be compressed by the force actin on the shell as the shot start, and locked in the compressed position by a brass blades 'staple' arming system. This new mechanism was to live a long life in the French next percussion systems.
A gunpowder room was machined parallel to the percussion system, linked to it at its upper extremity by a channel, and communicating to the shell at the fuze bottom by a vent.

At the shot start inside the barrel, the safety spring in the graze pellet was compressed by the recoil force, allowing the inertia block to move back and unmask the friction pin tip. This tip opened the brasse blades and was kept in this position by themd was the block was clipsed in this postion by them, arming the mechanism. In flight, only the protective membrane was preventing an accidental explosion.

At the impact on a target, the inertia block propulsed the percussion pin to the front. This one was easily peircing the protective membrane and triggered the primer. The created flame was communicated to the gunpowder room and amplified by it, then directed to the tail rear through the vent, triggering the shell ewplosion.

The Henriet fuzed was arming the olds a 5 and 7 explosive shells, but also the explosive shells more modern 80, 90 et 95 mm fieldguns, aa well as those of the 138mm siege gun. It was interchangeable with the 'fusée Budin Mle 1875 ', and these obsolete fuzes were very likely used with old shells stoks shot with these old guns coming back from arsenals durig the first period of WW1.


25/38 Mod 74/75 Henriet fuze. Notice the side hole in the thread, bored in order to allow the communication between the top of the gunpowder room and the percussion system. Its position permits to see the difference with a 74/75 model equipped with an elongated room.
25/38 Mod 74/75 Henriet fuze. Rear view with the almost central vent of the percussion system and the more exentric hole of the gunpowder room
25/38 Mod 74/75 Henriet fuze. Marking '75' gives the 1875 manufacturing year
25/38 Mod 74/75 Henriet fuze. Front view with the exentric upper screw of the percussion system.
25/38 Mod 74/75 Henriet fuze at the side of the Budin fuze with the same profile
25/38 Mod 74/75 Henriet fuze. Modern sheme showing the arming sequence using the brass blades staple and the percussion sequence on the target. Notice the gumpowder room parallel to the percussion mechanism room, typical of an original Mod 74.



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Budin fuze 25/38 Mle 1875
25/38 mm percussion fuze without detonator System Budin, model 1875

The years after the 1870 war, that had seen the Armies of the French Emperor Napoleon III being defeated by those of the young German First Reich, coincided with numerous developments of military technologies, particularily in the artillery domain, therefore in the fuzes technology as well.

The old percussion fuses Desmarest (1859) and Tardy (1860) were progressively replaced by a new generation of more sophisticated devices. The principles of those new percussion systems Henriet (1874), Budin (1875), Siège et Montagne (1878), Saussier (1887) et Robin (1888), equipped with more and more reliable safety, arming and percussion mechanisms, were afterwards used in the XXst century fuses.

The bronze Percussion fuse of 25/38 mm System Budin, model 1875 presented here was invented by the Lieutenant Budin. It seems to be inspired from the 1874 Henriet fuze whose principle has been globally kept (including the bras blades staple arming system), but shows three major modifications that provided new standards :
  • the percussion pin was now static and fixed to the top plug, while the primer ('percussion cap') was contained in the mobile graze pellet ('inertia mobile block') and could slide into it
  • this choice allowed to integrate the gunpowder room inside the inertia mobile block behind the primer, and consequently to have the percussion system back right in the fuze axis, a less sensible position to the centrifuge forces
  • a safety spring replaced the metal protection mebrace for the in-flight safety.
At rest, the percussion cap was maintained out of range of the the percussion pin since it was masked inside the cylindric mobile graze pellet positioned at the middle of the tail central room by the action of the safety spring on the top and the one of the protuding brass blades 'staple' on the bottom.

At the shot start, the inertia forces was violently pushing the mobile graze pellet backwards, pressing the brass blades and letting the percussion cap block entering entirely inside the central room of the block. Once unmasked this way, the primer was only separated from the friction pin by the safety spring during the flight time, and the shell was armed.

When hitting the target , the solidary ensemble mobile inertia block / percussion cap was propulsed towards the front, compressing the safety spring and came in contact with the percussion pin, triggering the shell burst under the action of the gunpowder room flame under the primer.

The fuze top plug bearing the friction pin was machined with a circumference rupture groove, allowing the head to fracture at this level at the impact without influence on the below percussion mechabism.

When this fuze was armed, a simple cm fall was enough to trigger its burst. Two modifications (1879 for the Navy, and 1881 for the Army) are known and indicated on the fuze body by a 'M' stamp.

The Budin fuze was arming the olds a 5 and 7 explosive shells, but also the explosive shells more modern 80, 90 et 95 mm fieldguns, aa well as those of the 138mm siege gun. It was interchangeable with the 'fusée Henriet Mle 1874 et 1874/75 ', and these obsolete fuzes were very likely used with old shells stocks fired with these old guns coming back from arsenals durig the first period of WW1.


25/38 Mod 75 Budin fuze. Markings : 'CP - 74', and two small 'B' on the cone top. It is an enigma to me that this item hs been built in 1874 (before the 75 mod adoption date ?)...
25/38 Mod 75 Budin fuze. Wartime scheme.
25/38 Mod 75 Budin fuze. Top view with the large head plug
25/38 Mod 75 Budin fuze. These 5 items markings show several manufacturing years ('74', '75', '76' et '77').
25/38 Mod 75 Budin fuze. Top view
Budin percussion system (extracted from a 25/38 Mle 1880 time and percussion fuze)
25/38 Mod 75 Budin fuze. Rear view of two pieces showing the flame communication channel from the gunpowder room
25/38 Mod 75 Budin fuze. Vintage scheme shomwing the arming sequence



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Fuze for 37 mm and 47 mm shells Mle 1877
13.5 mm fuze without detonator for 37 mm and 47 mm shells, system Desmarest, model 1877

In 1877, the Frech Army and Navy choose a miniaturized version of the 22 mm Mle 1859 Desmarest fuze for the 37 mm and 47 mm pig iron shells.

Apart from the reduced dimensions, the very simple inner mechanism of the initial Desmarest system was kept with the pushable wooden plug bearing the percussion pin, protected by a gum varnish layer and attached to the fuze body by nails, and the rear wooden piece holding the primer, fixed by pins, linked to the shell body by a drilled communication vent through the brass bottom and protected by a paper sheet.

The 25 Mle 1877 percussion fuze for 37 mm and 47 mm shells, system Desmarest profile was reduced proportionnally to adapt to the small 37 mm and 47 mm shells with a 13.5 mm tail thread, and the head was given a tronconic shape whose angle was related to the shell ogive instead of the hexagonal shape of the original fuze. A tin washer was providing the safe link between the fuze and the shell.

The Desmarest Mle 1877 fuze was used with the explosive projectiles of the
  • 37 mm guns : revolving guns, quick fire guns, Mle 1916 TR, SA modèle 1917 guns, SA Mle 1918, SA Mle 1918 and Mle 1937.
  • 47 mm guns : Mle 1885 and 1902.
An equivalent version was used by Germans for their 37 mm guns during WW1.


Mle 77 Desmarest fuze. Markings 'L4 7 4 16'. notice the tin washer.
Mle 77 Desmarest fuze. Front view on the wooden block protection.
Mle 77 Desmarest fuze. Rear view on the flamne vent
Mle 77 Desmarest fuze. View on an item still attached to its 37 mm shell. The wooden plug protection has disappeared and remains of wood can still be seen
Mle 77 Desmarest fuze. Modern scheme



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25/38, 30/45 and 40/55 S.M. fuze Mle 1878-81 and 1878-92
25/38, 30/45 and 40/55 mm percussion fuze without detonator Siege and Mountain ("S.M.") model 1878-81 and 1878-92

Designed in 1878 for the Siege and Mountain artillery ('S.M.'), whose bell-type trajectories setting needed the use of variaiable propulsive charges quantities that did not permit to ensure the arming of the usual percussion fuzes Budin or Henriet, the bronze fusée percutante Siège et Montagne (S.M.) modèle 1878 was built to be armed with the same safety standards whatever the initial speed given by the propulsive charge value. Moreover, its sensitivity allowed to provide a normal function at the arrival on the target even for relatively low speeds.

In order to reach this specicication, several modifications were provided to the classical percussion Budin system with mobile primer-bearer inertia block, safety spring and brase blades staple arming device :
  • heavier brass inertia mobile block to increase its inertia at the departure and at the impact
  • longer safety spring to withold the shots at high propulsive charge, but souple enough to be compressed by shots at lower charge
  • low energy arming system by a brand new washer staple located at the top of the inertia mobile block and engaging into the upper grooves of the percussion cap bearer slightly unmasked under the low energy of the low propulsive charge shots by a limited compression of the arming spring under the action of the inertia block
  • high energy arming system with a grooved lead flange placed at the tail bottom below the inertia mobile block, on which inner grooves machined inside the bottom of the cylindrical inertia block were engaging when this one was able to compress entirely the arming spring under the action of shots at high propulsivle charge.
These modifications were perfectly fullfilling theur mission for the use with bell-trajectory and low initial speed guns and howitzers, at the detriment of a considerable elongation of the fuze tail, making it uncompatible with light ammunitions, as well as a certain sensitivity to the shell stability in flight. Being designed to have a sensitive arming behavior, it was of course to handle with care since it could be armed just by a fall of 3 to 4 meters high !

These characteristics were at the origin of the choice of this fuze for equipping the projectiles of the very first reglementary French trench mortars, awaiting for the arrival of specific devices.

The Siège et Montagne percussion fuze was mainly used with the explosive shells of the
  • 120 mm and over heavy guns and mortars
  • 58 nr1 trench mortars

Many variants of that fuze are known, either due to modifications of their inner mechanisms (identified by the design year) or by their shape :

Inner mechanism variants :
  • the original fusée percutante Siège et Montagne (S.M.) modèle 1878 that had a plug-free head and a tail large bottom plug with a vent in order to insert the percussion mechanism by the rear
  • the fusée percutante Siège et Montagne (S.M.) modèle 1878-81 that was differing by the existence of a large head plug that was bearing the friction pin and allowing the insertion of the percussion system by the top. The tail rear was only pierced by the vent.
  • the fusée percutante Siège et Montagne (S.M.) modèle 1878-92 that appeared later and could be identified by its smaller front primer-bearer plug , and its large rear tail plug (with vent) allowing to insert again the percussion mechanism by the rear.
  • the fusée percutante Siège et Montagne (S.M.) modèle 1878-81 M15 was a very late variant of the mod. 1878-81 and was introduced in 1915, with a cylindrical head (replacing the usual trnoconic one) and re-inforded safety spring, designed to equipe the shells of the huge 370mm mortars

Profile and thread size variants (for adaptation to different shells) :
  • 25/38 (25 mm thread, cone base 38 mm)
  • 30/45 (30 mm thread, cone base 45 mm)
  • 40/55 (40 mm thread, cone base 55 mm)


25/38 Mod 78 Siège et Montagne fuze. Original model. Markings : '78'. Notice the considerable elongation of the tail compared to the previous fuzes types, necessary in order to include the double arming system.
Different variants of Siège et Montagne fuzes. Top view allowing to indentify the various variants : mod. 1878 (without plug), 1878/81 (large plug) and 1878/92 (narrow plug).
30/45 Mod 78-81 fuze. Several items including one still having a part of the shell
30/45 Mod 78-92 fuze. Several items including two still having a part of the shell
30/45 Mod 78-81 fuzes observed at Massiges (Champagne). Notice the exploded tail and shell envelopes. The visble thread is the one of the detonator ECP 12-14 in wheich the fuze tail was inserted. Markings : '30 45' - 'Mle 78 81' - '82' - 'ECP R 6 08'
30/45 Mod 78-81 fuze. Top view. Red paint traces at the bottom of the threads, typical of the mod 81 not modified 1915 (black paint). Markings : '81'
30/45 Mod 78-92 fuze. The '92' variant, that can be identified with its narrow plug, that has been partially ejected by the explosion. These models are less easy to find.
Different variants of Siège et Montagne fuzes. Rear view showing the different tail configuration; with simple vents for tyhe models 1878/81, and large tail plugs for the models 1878 and 1878/92.
Different variants of Siège et Montagne fuzes, and different threads. From left to right, 35/38 Mle 1878/92 (unusually with a thread adaptor on a 25/38 type), 30/45 Mle 1878/81, 25/38 Mle 1878/81, 25/38 Mle 1878, and 30/45 1878 (/92 ?).
30/45 Mod 78-81 fuze. This item is still on the shell remainings : a French 'mushroom' as nicknamed by the battlefield visitors, part of a medium caliber shell (as shown by the wall thickness), observed in Massiges (Champagne)
30/45 Mod 78-81 fuze. Wartime scheme. The rupture groove machined in the head plug was introduced with the Budin fuze and was made to keep the lower mechanism of the fuze intact, including the percussion pin, if the impact shock energy was big enough to break the fuze head



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Percussion fuze 24/31 Mle 1899 and 1899-08
24/31 mm percussion fuze with detonator model 1899 and 1899-08 system Robin - Lejay

The inertia percussion system with brass blades staple safety was subject to a new evolution in 1886 with the design known as the Robin system (name of its inventor). Starting from the 1875 Budin system used in the 25/38 Mod 1875 percussion fuze percussion fuze with a static percussion pin fixed under the head plug, and a mobile graze pellet bearing the primer and armed by a brass blades staples system, it was inheriting the improvements given in 1884 by the Saussier system used in the 30/38 Mod 1884 time and percussion fuze.

Briefly introduced by the Navy in its 18/28 Mle 1886 time and percussion fuze for 65mm shell, this new Robin system became famous with the 22/31 mm percussion fuze without detonator Mod. 1888, system Robin. It was introducing major evolutions, including :
  • a mobile arming inertia block with two external shoulders , one for the arming staple, the other fot the safety staple
  • an arming staple brass blades system equipped with a small inertia block and designed to grip the upper shoulder of the primer-bearer graze pellet at the shot departure, after the safety spring had been compressed.
  • a safety staple brass blades system pressing at rest against the primer-bearer pellet lower shoulder , keeping this latter in a low position, and opening itself at the shot departure under the action of the backwards movement of the inertia block
  • a safety spring designed to prevent in flight contact between the primer bearer inertia block and the percussion pin, not acting in compression between those two pieces, but rather acting in tension between the base of the mobile block and the fuze bottem.
This Robin percussion system was offering an improved safety although still providing a good sensitivity, and was adopted in the majority of the percussion or time and percussion French fuzes that will follow.

The most famous fuze that inherited this system was the 24/31 mm percussion fuze with detonator Mod. 1899 System Robin-Lejay, the first of the French percussion fuzes designed with an integrated detonator for the use on high explosive shells (not filled with gunpowder), and classical device used with French WW1 explosive shells of most calibers in August 1914.

The fuze was divided in three different parts :
  • at the middle, a cylundrical brass body with truncated head cone was hosting a Robin percussion system. The body had a 24 mm external thread and the cone base was 31 mm diameter.
  • at the head, a steel cap (or very seldom in brass) was including an additionnal safety system called Lejay system. It was a new inertia and staple arming system allowing to retract at the shot departure a cylinder that was masking the percussion pin.
  • at the rear, below the Robin system safety tension spring, a small brass tube included a 'fire relay' that was amplifying the primer flame. The body presented on this side a thread on which one could screw a 2 grams fulminate small cylindrical detonator, needed to make the high explosive shell charge detonate directly or with an intermediate bigger detonator.
This fuze was used on most of the high explosive projectiles of various calibers, completed when needed with a threaded ring that could adapt the shell holes dimensions to the fuze 24 mm thread, for the :
  • 75 mm Mle 1897 fieldguns
  • 80 mm Mle 1877 fieldguns
  • 90 mm Mle 1877 fieldguns
  • 95 mm Mle 1888 fieldguns
  • 120 mm guns
  • 155 mm guns and mortars
  • 58 Nr2 (heavy load LS bomb) and 75T trench mortars
In 1908, a 24/31 mm percussion fuze with detonator Mod. 1899-08 System Robin-Lejay variant was adopted, integrating a small 0,05 seconds delay in a shortened and enlarged tail tube, to allow the 75 mm fieldguns ricochet fire (allowing to destroy soldiers with percussion shells shot with a low propelling charge at a small (< 15 degrees) angle in order to bounce on the ground and explode at low altitude).

In 1914, the French Army had to admit soon that the artillery fire had to be made most of the time at a range too long to allow such tangeant fire. Consequently the original model non-delay fuzes were used again.

Both variants cannot be differentiated externally, unless if the safety steel cap paint is still visible ; white vernish for the delay-free original Mle 99 fuze, and black vernish for the delayed Mle 99-O8 fuze, or thanks to the rear tube shape.


24/31 Mod 99 or 99-08 fuze.
24/31 Mod 99 or 99-08 fuzes. This kind of fuze remnants such as the ones at the left can often be seen on ancient WW1 battlefields
24/31 Mod 99 or 99-08 fuze. Three entire items, with their detonator attached
24/31 Mod 99 or 99-08 fuze. At the left an unusual specimen on which the Lejay system cap is made in brass instead of steel.
24/31 Mod 99 or 99-08 fuze. Detonator removed
24/31 Mod 99 or 99-08 fuze. Rear view showing the arming staple blades Vand the mobile arming mobile inertia block with the two external shouldres, removed from its room inside the fuze.
24/31 Mod 99 or 99-08 fuze. Cap removed (picture Luc Malchair)
F24/31 Mod 99 or 99-08 fuze. Cut-through showing the Lejay system inside the fuze head cap
24/31 Mod 99 or 99-08 fuze. Note the original paint markings traces as well as the groove at the top tof the cap that allowed to unscrew the Lejay arming system
24/31 Mod 99 or 99-08 fuze. Wartime scheme showing marking types.
24/31 Mod 99-08 fuze (with 0,05 s delay). Wartime scheme



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Percussion fuze 24/31 Mle 1899-1915, systeme Robin
24/31 mm percussion fuze with detonator mod. 1899-15 first and second model, system Robin

The use of the 24/31 Mle 1899 and 1899-08 percussion fuzes was presenting some issues in particular situations :
  • with heavy artillery shells having an important impact energy and high residual speed, or with the 75 mm fieldguns shells hitting a herd surface, the steel head cap hosting the Lejay safety system could be damaged and penetrate inside the fuze body, preventing the Robin system to function appropriately and causing duds
  • with short barrel guns firing with small propelling charges, the initial acceleration could be too low to arm the fuze, this being another cause of duds.
A new model, named 24/31 mm percussion fuze with detonator, model 1899-15 (first model), system Robin, was then created as an evolution of the 24/31 Mle 1899 and 1899-08 percussion fuzes inspired by the first WW1 months experience that saw a more and more frequent use of the explosive shells, the increasing use by the French Army of heavy guns coming in addition to the 75 mm Mle 1897 batteries, and the invention of the trench artillery shooting low speed projectiles.

The new fuze was still keeping the 'Robin' percussion system of the 1899 and 1899-08 fuze, contained in a brass tube whose lower part was very similar, while the tronconic (with a right angle bevel at the base) upper part was more massive (and therefore more resistant), and did not integrate the 'Lejay' safety system for the percussion pin that was now fixed to a simple head plug.

In the 24/31 mm percussion fuze with detonator, model 1899-15 (second model), system Robin that came shortly after, the fuze head plug to which the percussion pin was attached replaced by a much smaller one (its diameter becoming similar to the one or the percussion pin) so that the fuze head was even more massive and resistant.

Three versions of both these models were existing, depending on the optionnal integrated delay value :
  • a fuze without delay ('sans retard' - SR) with a head painted in black
  • a fuze with a small delay ('court retard' - CR) of 0.05 seconds with a head painted in white
  • a fuze with a long delay ('long retard - LR) of 0.15 seconds with a head painted in white and the taoil in violet
These variants cannot be recognized if the marking is gone, unless traces of the head paint are still visible. The weakness of the safety spring in flight was a reason why some models were equipped with a stronger safety spring for the use with some kinds of guns whose shell could be subject to some instability on its trajectory. For these models the base bevelled sector of the tronconic head was painted in green.

A last variant with steel body and a short delay was also introduced in 1916 for the anti-tank fire, with a hemi-spherical head painted in yellow. This fuze was used with various calibers high explosive shells of many guns and mortars :
  • 75 mm Mle 1897 fieldguns
  • 80 mm Mle 1877 fieldguns
  • 90 mm Mle 1877 fieldguns
  • 95 mm Mle 1888 fieldguns
  • 120mm guns
  • 155 mm guns and howitzers
  • 220 mm guns and howitzers
  • 58 Nr2 trench mortars (LS bomb with middle or heavy charge)


24/31 Mod 99-15 fuze.
24/31 Mod 99-15 fuzes. First model (at left) with the large head plug and remains of black paint indicating a non-delayed fuze, and second model (at right) with the small head plug
24/31 Mod 99-15 fuzes. Side view of a first and a second model, unstinguishables.
24/31 Mod 99-15 fuzes. First and second models, tail detonators removed
24/31 Mod 99-15 fuze. Phicture courtesy Luc Malchair
24/31 Mod 99-15 fuze. Modern scheme (secon model with small head plug



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Mod 1915 Schneider fuze for 105 mm shells
Schneider percussion head fuze M 1915 with detonator for middle caliber shell.

Usually restricted to the French Army arsenals such as the Ecole Centrale de Pyrotechnie, the design and manufacturing of the WW1 French fuzes was extended to some private companies, whose artillery weapons designed for exportation were progressively adopted by the Head Quarter.

This is how the adoption of the good 105mm Mle 1913 fieldgun of the Etablissements Schneider in Le Creusot (Burgundy) opened the door to the delivery by the same company of ammunitions and fuzes of its own design too. This explains why these devices not designed in the usual arsenals sometimes integrate radically different technological choices.

This is the case with this brass Schneider percussion head fuze M 1915 with detonator for middle caliber shell, that was atypical for several reasons :
  • its tail and thread diameter (47,5 / 55 mm) is specific to the Schneider 105 mm mod 1913 high explosive shell
  • its shape and heavy weight are uncommon as compared to the other French percussion fuzes usually lighter
  • the two steps arming of the percussion system was using both the effects of the inertia and the centrifugal force
  • it is the only percussion French fuze equipped witn a pyrotechnic arming system that was doubling the percussion system safety device

The ingenious percussion system designed by Schneider was functionning thanks to inertia and its arming was based on both inertia and spin. It was composed of a static percussion pin, separated from a primer-bearing heavy graze pellet by a safety spring. This pellet movements were prevented at rest by segments pushed inside a groove machined on the pellet by a spring wrapped around them. A cylindric safety ring was pressed against the upper part of the pellet room by a ring spring.

A the shot departure, inertia forces pushed back the safety ring around the segments, compressing its spring. As long as the acceleration was continuing, (in the barrel), The segments were not able to spread despite the shells spin and the fuze was secure. At the muzzle exit, the acceleration stopped, and the ring spring was pushing up the ring. This allowed the segments to spread under the effect of the centrifugal force that was ellarging the spring wrapping them. The graze pellet movements were now only prevented by the safety spring palced between the percussion pin and the primer carp. At the impact, this spring was easily compressed by the arrival shock propulsing the pellet frontwards and provoking the explosion. The primer flame was transmitted to the tail detonator (Schneider type) through a vent.

This percussion system was reproduced, with a scale factor, in the several 24/31 Mod 1916 Percussion fuzes system Schneider.

Located in the fuze head top under a threaded plug, the additional pyrotechnic safety system was acting like most of the German fuzes systems ; at the shot departure, a concutor was hitting a small primer igniting a gunpowder pellet. The combustion of this pellet freed the movements of a piston that was maintaining at rest the heavy graze pellet and was also masking the tip of the percussion pin.

The fuze was hermetic and the absence of any combustion gasses escape vent was compensated by an inner reservoir room.

This fuze was excluvely used with the high explosive shells of the
  • 105 mm Mle 1913 Schneider fieldguns
It wa available in a version without any delay, or in a long lle a été développée en version non retardée, ou a long retard de 0,25 seconds delayed version

Alternative accentuated conical shape versions have been observed on the battlefields (see pictures) but no relative information was found.


Mle 1915 Schneider fuze for middle caliber shell. Associeted to the specific tail detonator made by Schneider as well (picture Luc Malchair)
Mle 1915 Schneider fuze for middle caliber shell. View on the specific Schneider tail detonator (unscrewed) - Picture Luc Malchair
Mle 1915 Schneider fuze for middle caliber shell. Another item observed in Champagne. Only the upper part survived : the 47,5 mm thread has been destroyed
Mle 1915 Schneider fuze for middle caliber shell. Original version (at the right) together with the unidentified variant (at left) observed in Champagne.
Mle 1915 Schneider fuze for middle caliber shell. Rear view that shows just like a cut-through at the level of the thread : both the variant and the original one seem identical viewed from below
Mle 1915 Schneider fuze for middle caliber shell. Two specimens : one is still mounted on a 105mm Schneider shell top remnant. Upper view with the screwed plug hiding the pyrotechnic safety
Mle 1915 Schneider fuze for middle caliber shell. Side view of the two specimens; the shell burst almost expelled the left fuze from the steel ogive.
Mle 1915 Schneider fuze for middle caliber shell. Wartime scheme



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24/31 Schneider percussion fuze
24/31 percussion fuze with detonator model 1916, system Schneider

The Le Creusot Schneider plants know-how was famous throughout the world in various metallurgy and mechanics techniques, including artillery. Rather succesful in export markets before WW1, they participated to the French war effort by designing and manufacturing guns and ammunitions.

In 1916, Schneider proposed a new percussion fuze based on the percussion mechanism developped for its Schneider percussion fuze Mle 1915 for middle calibre shells, and supposed to replace the instant effect percussion fuzes 'I' Mle 1914 and 'I.A.' Mle 1915 or 'I.A.L.' Mle 1916 that were experiencing numerous issues.

This 24/31 percussion fuze with detonator model 1916, system Schneider was entirely made of brass. Its shape was similar to the one of the classical French percussion fuzes using the 24/31 template as well as the profile of its most usual variants (Tracés A. 1644 B., A. 1772 and A. 1820 similar to the Robin-Lejay fuze Mle 1899; Tracés A. 1644 B.A. and A. 1853 similar to the Peuch fuze Mle 1914).

In the inside, the fuze was using the percussion mechanism of the Schneider percussion head fuze M 1915 with detonator for middle caliber shell with smaller scale dimensions, with the same two-steps arming mechanism by inertia (ring) et centrifugal force (segments), but withoiut the additional pyrotechnics armin system.

Since the mechanism could only be armed by rotation speeds > 12000 turns/minute, this fuze could only be used with the projectiles of the 75mm Mle 1897 fieldgun. The attached explosive charge was again a 2 grams fulminate detonator. The fuze was existing in 2 versions : one without delay (head painted in white), and one with a small 0.05s delay (head peinted in black).

The same base was used for several fuzes, whose most known ones, named by their Schneider's catalog 'numéro de tracé' (dramwing number) were :
  • a first group composed with fuzes whose head and body were made oof a single block, and whose tail detonator (left male thread) was screwed inside an adptating ring (left thread) attached to the fuze body :
    • Tracé A. 1644 B. de 24/31 mmwith a profile similar to the one of the Robin/Lejay Mle 1899 fuze
    • Tracé A. 1644 B.A. de 24/31 mm with a shorter head and a profile similar to the one of the 'I' fuze Mle 1914 Peuch
    • Tracé A. 1644 D. ter. de 24/40.5 mm with an ogival head
  • a secong group composed of fuzes whose head and body were assembled, and whose tail detonator Un second groupe formé de fusées dont la tête et le corps étaient assemblées, et dont l'amorce de détonateur (left male thread) was directly screwed inside the female thread of the fuze tail whose lower profile was straightening :
    • Tracé A. 1772 de 24/31 mm with a profile similar to the one of the A. 1644. B. fuze and the Robin/Lejay Mle 1899 fuze
    • Tracé A. 1820 de 24/31 mm with a profile similar to the one of the A. 1644. B. fuze and the Robin/Lejay Mle 1899 fuze
    • Tracé A. 1853 de 24/31 mm with a profile similar to the one of the A. 1644. B.A. fuze and the 'I' fuze Mle 1914 Peuch
  • an elongated fuze :
    • Tracé A. 1837 de 24/31 mm with a profile similar to the one of the I.A. fuze system Lefèvre
These fuzes were used with the chemical and high explosive shells of the
  • 75 mm Mle 1897 fieldguns


Schneider Fuze Mle 1916 tracé A. 1644 B. Notice the profile similar to the 24/31 Robin/Lejay Mle 1899 fuze
Schneider fuze Mle 1916 tracé A. 1644 B. A first evident difference with the 24/31 Mle 1899 fuze is the head cap in brass instead of steel and not screwed to the body.
Schneider fuze Mle 1916 tracé A. 1644 B. Another major external differnce with the 24/31 Mle 1899 can be seen with the tail detonator whose male thread is inserted inside a brass adaptator ring.
Schneider fuze Mle 1916 tracé A. 1644 B. This specimen still shows some white paint traces that designate a non-delayed variant
Schneider fuze Mle 1916 tracé A. 1644 B. Zoom on the top cap with the hole containing the pin that was holding the percussion pin holder in position
Schneider fuze Mle 1916 tracé A. 1644 B. (top) and Schneider fuze Mle 1916 tracé A. 1853 (bottom). In addition to the evident head cap height difference, notice the tail profile difference, the tail detonator fixing difference, and the joint difference between the head cap and the body, typical to the two main families
Schneider fuze Mle 1916 tracé A. 1772 or 1820. The scewed head typical of this family is almost removed by the shock.
Schneider fuze Mle 1916 tracé A. 1853. This time the profile is similar to the one of the 24/31 'I' Mle 1914 fuze
Schneider fuze Mle 1916 tracé A. 1644 D. ter. of 24/40.5 mm. These fuzes profile is completely different, with a very specific conical head.
Schneider fuze Mle 1916 tracé A. 1772 or 1820. on a 75 mm shell ogive
Schneider fuze Mle 1916 tracé A. 1772 or 1820. wartime scheme



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24/31 Mod 1916 'P.R.' percussion fuze
24/31 Mle 1916 percussion fuze with detonator, system Peuch-Remondy, for trench artillery

In 1916, Captain Remondy improved the helicoidal ramps safety system of the 24/31 Mod 1914 percussion fuze system Peuch, in order to make it compatible with the projectiles and firing conditions of the trench mortars.

In this new new version, logically taking the name 24/31 Mle 1916 percussion fuze, system Peuch-Remondy, the designer was introducing several improvements. As a first noticeable one, the head system with a mobile percussion-pin bearing plug pressed against the inner room by steel balls was replaced with a simple massive head including the percussion pin. This characteristic made the fuze particularily robust and less sensitive to humidity, therefore better adapted to the tough conditions of the trench artillery.

The safety device with rear inertia block, helicoidal ramps mobile inertia block with primer cap and the separated safety section masking the primer was also slightly modified. Whereas the upper mobile safety section was kept similar with its diagonal-ramps cut teeth, this time the lower mobile inertia block was composed of a symetrical hollow section with the opposite diagonal-ramps cut teeth, and the primer cap was now located in a new distinct central cylinder around which the upper and lower sections could slide and equipped with lateral studs whose faced were machined to adopt the shape of the space between the two helicoidal ramps of the upper and lower sections.

This new safety device allowed an arming process in two steps :
  • At rest a lower arming spring was holding the teethed lower mobile inertia block in up position, its teeh imbricated between the ones of the symetrical upper mobile safety section that was pushed against by a upper compressed safety spring. The lateral studs of the inner mobile cylinder bearing the primer were inserted between the imbricated teeth of the two mobile blocks, in contact with the bottom of the lower mobile block teeth and the top of the upper mobile block teeth. This global position was keeping the upper safety section in top position, masking the percussion cap of the inner cylinder and hence keeping this one out of range of the persussion pin.
  • At the shot departure under the action of the initial acceleration, the teethed lower mobile inertia block was pushed back and compressed the lower arming spring, while the upper mobile safety section was also pushed back, its teeth being forced to slide on the ramps of the inner cylinder studs and therefore giving the upper mobile block a rotation movement that was communicated to the lower teethed block by contact between the teeth lateral walls. This recoil and rotation complex movement allowed in a first time the lower block teeth tops to reach the level of the studs under the recoil action and then slide on them under the action of the rotation movement, making both upper and lower teethed blocks rotate about 1/6th of a turn. At the end of the movement, the ramped studs of the inner cylinder were located in the space between the bottom of the mobile upper section teeth and the top of the mobile lower section teeth, keeping from now on the lower arming spring compressed and unmasking the primer cap.
  • In flight from the exit of the muzzle, whith no more acceleration applied and the lower arming spring kept compressed, the upper safety spring was pushing back the locked assembly of the upper and lower teethed mobile blocks and the cylindrical primer-bearer block with the lower arming spring compressed and the primer unmasked, preventing this latter to be in contact with the percussion pin.
  • At the impact, the heavy locked mobile assembly was propulsed frontwards, compressing the upper safety spring, so that the percussion pin was igniting the primer. The resulting flame was communicated to the tail small detonator through a small pyrotechnic relay that could be added with a delay.
This system was designed to be armed under low accelerations, and therefore fully adapted for equipping the low-speed projectiles of the
  • 58 Nr2 (LS and DLS bombs with all possible propulsive charges) trench mortars
  • 150T and 240 LT trench mortars
This Peuch-Remondy fuze was developped both in an instantaneous version (fuze head painted in white) or with a 0.2 seconds delay (fuze head painted in black). The early models had a plain head body, the percussion pin being screwed in place from the body inside. Already in 1916 a modification was made with a small head threaded hole allowing to screw the percussion pin from the head. A more rare variant also existed with a large top head plug bearing the percussion pin .


24/31 P.R. fuze Mod 1916 with its tail detonator. This fuze made for low accelerations is still particularily sensitive and dangerous.
24/31 P.R. fuze Mod 1916. Second model with the head top small hole for the percussion pin insertion. This one is mounted on the upper part of a trench artillery bomb through a specific adatator.
24/31 P.R. fuze Mod 1916. Detonator removed (empty) - picture Luc Malchair
24/31 P.R. fuze Mod 1916. Initial model with plain head at the right, and second model with small head hole at the left. Both items are still attached to the remains of a trench artillery bomb that has been flattened by the explosion, but recognizable by their thin steel walls.
24/31 P.R. fuze Mod 1916. Paint markings remains on the cone
24/31 P.R. fuze Mod 1916. Wartime scheme explaining the inner mechanism arming sequence
24/31 P.R. fuze Mod 1916. Wartime scheme with a zoom on the helicoidal ramps



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Instant effect fuses


24/31 'I' fuze Mle 1914 system Peuch
24/31 instantaneous percussion fuze 'I' de 24/31 model 1914, system Peuch

In 1914 a new fuze was introduced, designed by the Workshop Manager Peuch of the French 'Ecole Centrale de Pyrotechnie'. Even if the shape and proportions could suggest just a small evolution of the classical percussion fuzes 24/31 Mle 1899 et 1899-08 Robin / Lejay, it was indeed a completely different inner mechanism that was proposed, giving birth to the first instantaneous (or 'quick action' French fuze.

The fusée-détonateur percutante 'I' de 24/31 model 1914 ''I' Instananeous percussion fuze with detonator, system Peuch was inheriting several innovating devices that allowed it a very quick percussion action by inertia and push-back :
  • a percussion system based on a classical mobile graze pellet (inertia block) with primer cap / static percussion pin / safety spring kind, but equipped with a really ingenious delayed action inertia arming system that was acting at the shot start by imbrication of a safety block in the mobile inertia block bearing the primer, that constituted with a rear inertia block a particularily quic acting inertia block propelled to the front at impact time
  • a push-back head plug simply inserted as piston inside the fuze top body, and held in place by the pressure of a tronconic screw on steel balls, and bearing the percussion pin. This latter could be propulsed towards the primer cap if the head plug was pushed back ay impact with a force sufficient to make the steel balls indent the brasse body
  • a tubular compressed gunpowder pyrotechnic relay that was transmitting the percussion cap flame very quickly to the small detonator filled with fulminate (2 grams) and screwed to the tail.
The delayed arming mechanism of the percussion system was based on the existence from top to the bottom of a hollow cylindrical safety upper mobile block with three teeth oriented backwards and machined with a helicoidal ramp shape, a symetrical lower inertia block with the same shape but whose teeth were oriented frontwards, a disc-shaped back inertia block with two pins parallel to the fuze axis, and a inner mobile rod that could slide inside these trhree hollow pieces and holding the percussion cap at its top.

At rest, the upper safety mobile block and the lower mobile block were placed teeth to teet, held together by the two pins of the disc inertia bloc traversing them, and by a small transverse tin pin. The upper safety spring located between the upper mobile block and the percussion pin, as well as the smaller arming spring wrapped around the base of the primer-bearer rod below the disc-shape mobile block were also maintaining this assembly at an intermediate position. In that elongated configuration, the assembly was long enough to mask the central rod's upper peimer cap that was therefore kept unaccessible to the percussion pin.

At the shot departure , the disc-shaped lower mobile bloc was violently pushed back, compressing the small rear arming spring and removing its two pins from the upper cylindrical teethed inertital block. The teethed inertia blocks were still held up for some tiny moments by the transverse tin pin, and the upper mobile block was given a rotating force under the action of the helicoidal cut teeth pressing against each other finally shearing the tin pin. The blocks then moved backwards, while the upper block rotation made the two block teeth mesh inside each other profiles. This was shortening the the two mobile blocks assembly, unmasking the percussion cap located at the top of the central rod.

At the muzzle exit, with the disappearing acceleration, la masselotte arrière en forme de disque était repoussée vers l'avant avec sa tige sous l'effet de son ressort arrière, et formait dès lors avec les deux masselotes cylindriques un solidaire mobile autour de la tige mobile porte-amorce. The fuze was therefore armed, and during the flight only the upper safety spring was preventing the primer cap to be hit by the percussion pin.

At the impact, the assembly made of the three inertia pieces was violently propulsed frontwards, compressing the upper safety spring. The mobile rod was also propulsed to the same direction, making a contct between the primer cap and the percussion pin. As said before, the percussion pin could also in m8any cases be propelled towards the primer cap when the fuze head was hitting a resistant enough target.

This system insured a much quicker triggering at the impact than the Fuze Mod 1899, exploding assurait un fonctionnement nettement plus rapide que la fusée modèle 1899, usually exploding as soon as the shell entered the ground only until the ogive level, suitable for uses where the anti-personnal effects were needed,and therefore deserving its classification in the 'instantaneous' fuzes. This fuze plug was usually painted in red, sometimes in white or blue instead.

The 24/31 'I' Peuch fuze was mainly used with high explosive, chemical or incendiary shells of the
  • 5 mm Mle 1897 fieldguns
  • 80 mm Mle 1877 fieldguns
  • 90 mm Mle 1877 fieldguns
  • 95 mm Mle 1888 fieldguns
  • 120mm guns
  • 155mm howitzers and mortars
  • 75T trench mortars
, particularily when surface effects were needed.

However, these fuzes were not compatible with the conventional trench warfare artillery weapons such as the classical 58, 150 or 240 mm mortars, whose shot start energy was not sufficient to arm the fuze.


24/31 Mod 1914 'I' fuze. Side view of the fuze easily recognizable shape and the detonator screwed to the tail end.
24/31 Mod 1914 'I' fuze. Another very common artefact that can be seen on former battlefields. Most of the fuzes that ca be observed on the ground have lost their push-back system head plug
24/31 Mod 1914 'I' fuze. View on the head plug of two similar items, one of them kept traces of its original red paint
24/31 Mod 1914 'I' fuze. The tail detonator has been unscrewed, notice the long tube for the pyrotechnic relay charge.
24/31 Mod 1914 'I' fuze. The tail detonator has been unscrewed, rear view on the pyrotechnic relay tube, and a remaining fedora disc.
24/31 Mod 1914 'I' fuze. Nice item still attached to an adaptator that was probably used for 155 mm shells. Notoce the head plug that seems to have been pushed back at impact
24/31 Mod 1914 'I' fuze. Wartime scheme explaining the arming process
24/31 Mod 1914 'I' fuze. Wartime scheme
24/31 Mod 1914 'I' fuze with adaptator and a shell detonator (empty). Red paint traces are still visible.



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22/31 'I' Mle 1915 system Peuch for Naud shell
22/31 'I' instananeous fuze with detonator system Peuch for naud shells

A variant of the 24/31 Mle 1914 'I' Peuch percussion fuze was introduced in 1915, with the same inner mechanism but with a modified body to make it compatible with the 30/38 mm shell detonators of the Naud type chemical shells loaded with phosphorus.

This '22/31 mm Mod 1915 percussion instantaneous fuze' was also very useful for the use with old obsolte high explosive shells having a small 22 mm thread ogive hole.

This fuze was mainly used with the high explosive, chemical or incendiary projectiles of the
  • 80 mm Mle 1877 fieldguns
  • 90 mm Mle 1877 fieldguns
  • 95 mm Mle 1888 fieldguns
  • 120mm guns
, and particularily with the Naud shells loaded with phosphorus.


22/31 'I' Mle 1915 fuze.
22/31 'I' Mle 1915 fuze (at left) compared to a classical 24/31 'I' Mle 1914 fuze that came first, in order to compare the profiles main differences : longer head and longer tail.
22/31 'I' Mle 1915 fuze. Rear view on the shell detonator (rmpty) with some markings
22/31 'I' Mle 1915 fuze. Another comparaison with the 24/31 Mle 1914 fuze. Both heads seen from the top are similar.
22/31 'I' Mle 1915 fuze. Another comparaison with the 24/31 Mle 1914 fuze.
22/31 'I' Mle 1915 fuze. Equipped with the detonator for Naud shells (empty)
22/31 'I' Mle 1915 fuze. Wartime scheme



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'I.T.' fuze with or without delay for trench artillery
24 mm 'I.T.' Mod. 1915 instantaneous stem fuze with or without delay for trench artillery

After a first year of improvising starting in the end of 1914, leading to the creation of the 58 Nr1 trench mortar in January 1915, the French trench artillery is equipped in spring 1915 with the first reglementary materials with the 58 nr1 bis and 58 nr2 trench mortars.

A simple quick action fuze is soon created to arm the fin tailed bombs of differnt sizes, and replace the momentaneous use of the Siège et Montagne fuze that was initially used with the 58 Nr1. trench mortars

This 24 mm 'I.T.' Mod. 1915 instantaneous stem fuze with or without delay for trench artillery ('I.T.' for 'Instantanée de Tranchées' - Trench Instantaneous) was really basic, but proveed itself very efficient for its planned use, thanks to the long rod it was adding to the top of the trench mortars bombs in order to have is exploding before the main body hits the ground.

The inner organisation was absolutely simple, with a rigid percussion rod guided inside a wooden cylinder inserted in the tubular stem body of the fuze. At the top end, this rod was linked to a mushromm shaped push button in aluminium, traversed by a soft metal pin. At its lower end, the percussion rod was turned into a percussion pin placed in front of a primer cap.

The only safety device of this very simple fuze was the soft metal pin, strong enough to resist the bomb start acceleration and the air pressure on the mushroom-shaped push button, but easily sheared by the the aluminium head when it was hitting the target surface, intantaneously pushing back the rod and making the percussion pin hit the primer cap located at the fuze bottom and detonating the bomb via an usual 2 grams fulminate tail detonator and a shell big setonator.

This fuze is known in two variants :
  • a variant without delay, really instantaneous in order to maximaize the explosion surface effects above the ground
  • a variant with a 0.2s delay, in order to trigger an explosion after some penetration of the bomb in the ground for digging effects. The percussion stem of this one was 2 cm shorter, and the wooden cylinder was shortened too to give some room to a pyrotechnic chain including a flame amplifier and a delay.
The two variants were easily recognizable : the delayed one was painted in black, and the space between the upper surface of the tail detonator and the tube base was measuring 4 mm, while the non delayed equivalent space was 1 mm.

At rest, the fuze head was protected by a tin hat, and a brass ring preventing any movement of the push-back button during the transport. It had to be removed before use.

The 'I.T.' fuze was mainly in use with the bombs of the
  • 58 n°1 bis tre,nch mortars (16 kg and 40 kg, D.L., D.L.S. bombs)
  • 240 mm trench mortars (87 kg bombs)
In 1917 the I.T. fuze was subject to a major evolution with the apparition of a new 'I.T.R.' fuze Mle 1917 ('R' fur 'Remondy') and later the shortened 'I.T.R.' fuze Mle 1918, more sophisticated, integrating an inertia arming system and a safety spring, and compatible also with the 150T trench mortars. Their mechanism was used for the R.Y.G. Mle 1918 fuze.


I.T. Mod 1915 delayed fuze
I.T. Mod 1915 fuze for trench mortar. Tweo items. The one on the top still owns its mushromm-shaped aluminium push-button while the one of the below fuze has disappeared.
I.T. Mod 1915 fuzes for trench mortar. The space between the tail detonator and the fuze bottom is larger for the item on top, indicating a delayed model. The one below could the be a non-delayed model.
I.T. Mod 1915 fuze for trench mortar. rear view with the standard tail detonator.
I.T. Mod 1915 fuze for trench mortar. Mounted on a 16kg (or LS) bomb head, whose diamter was around 140 mm
I.T. Mod 1915 fuze for trench mortar. Wartime scheme of the delayed and non delayed models.



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'I.A.' modèle 1915 and 'I.A.L.' model 1916 fuze
24/31 mm elongated instantaneous percussion fuze with detonator, model 1915 and 1916 system Lefèvre

The 'I.A.' Model 15 fuze ('Instantanée Allongée') appeared in 1915, designed to obtain even quicker explosions when touching the ground than with the 24/31 Mle 1914 'I' Peuch fuze. In order to achieve that, the percussion mechanism of the I.A. fuze was located at the very top of a 12 cm long brass rod, and the transmission of its flame to the shell was insured by nothing less than a detonating chord (tin tube filled with melinite).

This percussion mechanism was included inside a steel body at the top of the bass rod, and consisted in a mobile percussion pin attached to a top head steel push-button and a static primer cap, without any safety spring to separate them from each other. At impact time, the push button was pushed back violently and had the percussion pin hit the static primer cap. The ignition of this one induced tye explosion of a small powerful detonator located in the head, that triggered the long melinite detonating chord. This latter was instantaneously provoking the explosion of a fuze tail detonator.

At rest this fuze was secured by three systems :
  • The percussion pin push-button movements were prevented by a safety made with a brass thin band wrapped in spiral around two half rings circling the percussion pin section below the button. The inner extremity of the band was attached to one of the half rings, while the outer extremity was ended by a small steel inertia section. This system was given the name of its inventor - 'Lefèvre'.
  • A shear pin was traversing both the percussion pin rod and the top steel body, preventing the percussion pin movements
  • During storage and transport, the whole fuze head was covered by a tin tightb finger that had to be removed before use.
At the shot departure, the wrapping direction of the brass spirals was such that the sudden spin accelearation of the shell inside the tube was tightening them, insuring the fuze safety inside the barrel.

At the muzzle exit the shell rotation speed became constant and allowed the centrifugal force to eject the small steel inertia section located at the external end of the brass spiral, unwrapping this latter, and finally ejecting the half rings, arming the fuze.

In flight, the tin shear pin only was preventing the percussion pin to enter in contact with the primer cap, despite the air pressure against the button.

At impact on the target the push-button was violently pushed back with enough force to easily cut the sagety shear pin, allowing the percussion pin to hit the primer cap.

There was two models with opposite brass spiral wrapping directions :
  • non painted fuzes - the models for barrels rifled to the right an with high initial speed were not painted, had their spiral wrapped clockwise and one of their half rings was notched on its lower edge. They could be armed with a shell spin speed > 3000 turns per minute with the sequence described above
  • red painted fuzes - the models used for barrels rifled to the left, or for barrels rifled to the right with low initial speed were painted in red, had their spiral wrapped counter-clockwise, and one of their half rings was notched on its upper edge. They coul be armed under a shell spin speed > 1800 turns per minute under the same exact sequence for the barrels rifled to the left, and slightly differentently for the ones rifled to the right.

As a consequence of numerous firing accidents, a modified 'I.A.L.' Model 1916 was manufactured afetr the works of André Lefèvre, Auxiliary Engineer of the Powders, and specialist of the primer caps detonation transmission.

In this new version, the long and dangerous axial detonating chord, guilty for many unwanted explosions in the barrels, was replaced by a hollewed inner channel communicating the flame of a 2 grams fulminate primer located in the head to the fuze tail detonator. This new model was also existing in a uncolored verion (for barrels rifled at right and with high initial speed), or painted in red (for barrles rifled to the right or to the left, with low initial speed).

Noticeable differences could also be seen in the shape of the mushroom-shapes pushbutton at the top of the long fuze, as well as in the thread type of the tail (female for a male threaded detonator for the 'I.A.' model, male for a female threaded detonator for the 'I.A.L.' model).

The I.A. and I.A.L. fuzes were mainly in use with the high explosive shells of the :
  • 75 mm Mle 1897 fieldguns (non colored head)
  • 95 mm system Lahitolle guns (red head)
  • 120mm guns
  • 155 mm C Schneider; 155 mm St Chamond and 155 mm L rifled to the right (non colored head)
  • 155 mm Mle 1881, 155 mm Mle 1890 and 155 mm TR Mle 1904 rifled to the right (red head)

They remained subject to unwanted explosions whenever braking suddenly inside the barrel of the gun, and their shape influence on the shell's aerodynamics was affecting the range so much that it had to be taken into account in a specific table.


I.A.L. fuze Model 1916
I.A. fuze Model 1915 and I.A.L. fuze Model 1916. The two successive versions side to side with (blow) the I.A. Mle 1915 fuze, and (above) the I.A.L. Mle 1916 fuze. They can be recognized by small differences that are detailed in the two pictures below.
I.A. fuze Model 1915 and I.A.L. fuze Model 1916. The 1915 version I.A. (right) is identified by its male threaded detonator, while the 1916 I.A.L. version has a classical female threaded detonator.
I.A. fuze Model 1915 and I.A.L. fuze Model 1916. Another diference is the top button shape, massive and hemispherical for the 1915 version (above), flatter for the 1916 one (below).
Fusée I.A. Mle 1915. Male threaded detonator and steel head removed
Fusée I.A.L. Mle 1916. female threaded detonator and steel head removed
I.A. fuze Model 1915 and I.A.L. fuze Model 1916. Steel top head bodies rear view
Fusée I.A.L. Mle 1916. This one suffered, but allows to see the flame channel through the brass body
fuze Model 1915 and I.A.L. fuze Model 1916. Wartime schemes



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T.C.A.L. Mle 1917 and 1918 fuze
24/31 mm T.C.A.L. Mle 1917 and Mle 1918 instantaneous percussion fuze with detonator, system Lefèvre

The long profile of I.A. Mle 1915 and I.A.L. Mle 1916 fuzes was giving way to some inconveniences
  • the long brass rod with the steel top body had a very high center of gravity was was modifying the equilibrum of the lighter shemlls and could affect their trajectories
  • at the impact the long fuze could be torn or broken, preventing it to function properly
So in 1917 a new T.C.A.L. Mle 1917 fuze ('T.C.A.L.' for 'TronConique Allongée Lefèvre') was introduced, much shorter but keeping most of the inner devices principles of the I.A.L. fuze

Just as in this latter, the brass or steel rounded upper push button was linked by a long rod to the percussion pin that could hit a primer cap now located at the fuze body bottom, igniting the tail detonator. The T.C.A.L. fuze safety was provided by a triple system similar to the one of the I.A.L. one :
  • unwrapping of a brass spiralled band and ejection of half rings after the muzzle exit under the effects of the centrifugal force given by the shell's spin (système 'Lefèvre'). All models were designed for the same shell's rotation direction than the ones of the non painted I.A.L. Mle 1916 fuzes.
  • soft metal safety pin traversing the percussion pin body, preventing the in-flight explosions under the air pressure, but easlily sheared by the impact schock
  • fuze head covered by a tin cap that had to be removed before the use.
The drastic shortening of the brass body's length of this fuze compared to the elongated instantaneous fuzes was improving the ballistic properties but at the cost of a shell triggering quite closer to the ground, although without big detriment to the quick action need.

This fuze was mainly in use with the high explosive shells of the :
  • 75 mm Mle 1897 fieldguns

The slightly modified 1918 version and the original 1917 one were not recognizable externally, the main difference being the change of the tail pyrotechnic system (percussion pin - upper primer cap - primary primer - tail detonator for the T.C.A.L. Mle 1917 fuze; percussion pin - upper primer cap - tail detonator for the T.C.A.L. Mle 1918 fuze).


T.C.A.L. Instantaneous fuze.
T.C.A.L. Instantaneous fuze. Lefèvre safety system still in place.
T.C.A.L. Instantaneous fuze. Top view. This item push button is in brass. Other ones had a steel push_button instead.
T.C.A.L. Instantaneous fuze. Rear view. 'M' marking on the brass spiral above the push-button
T.C.A.L. Instantaneous fuze. The tail detonator has been removed. Notice the tip of the percussion pin showing up at the base of the fuze body
.
T.C.A.L. Instantaneous fuze. The tail detonator (empty) has been removed.
T.C.A.L. Instantaneous fuze. Accompanied at right by its post-war successor, the T.C.A.L. Mle 1926 fuze
T.C.A.L. Instantaneous fuze. Modern scheme



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24/31 model 1917 RY fuze
24/31 mm model 1917 instantaneous percussion RY fuze with detonator, system Remondy

The (Elongated instantaneous fuzes I.A. and I.A.L. and Elongated instantaneous fuze T.C.A.L.) equipped with a 'Lefevre' type arming system could only be armed under the action of a shell minimum spin speed. This was a limitation that induced the design of a new instantaneous system that was useable with projectiles indifferently of their rotation speed or direction, as well as in a large spectrum of initial speeds.

This how the Captain Remondy, already inventor of the 24/31 Mle 1916 'P.R.' percussion fuze, had accpted by the Army in 1917 a brand new quick action fuze that was fully answering to this need.

This 24/31 mm RY model 1917 instantaneous percussion fuze, (RY as 'RemondY'), entirely made of brass and covered at rest by a crimped tin hat, using the conjunction of a purely inertia action arming system and a push-back percussion device.

The hollow percussion pussh-button was placed at the top extremity of a long axial percussion rod bearing the percussion pin at its lower end. A strong percussion spring inserted in a room under the push-button was preventing the movements of this rod. the primer cap block was mobile and located at the base of the fuze tail. It was a long tube in which the percussion rod was able to penetrate and the primer cap was located at its lower end, out of range of the percussion pin at rest even if the percussion head was fully pushed back.

The upper section of this tube was machined with two grooves. A tubular mobile safety inertia block was able to slide around the primer cap block upper section, and was equipped with three flexible brass blades staples whose extremities could grip the primer cap block grooves

At rest the staples were gripping the primer cap block by the upper groove (named safety groove) and were held closed in this position under the action of a small mobile tubular inertia block around the mobile safety inertia block blades. An intermediate strength spring was keeping the small tubular block in upper position, and the mobile primer cap block in lower position.

At the shot departure, at first the shell acceleration in the barrel was pushing backwards both the percussion head and the rod (compressing the strong percussion spring), whose lower percussion pin was closer but still out of range of the primer cap, and the mobile tubular inertia block (compressing the intermediate safet spring) and allowing the brass blades staples to open. This alloweed the second arming step, the tubular safety inertia block now being free to slide backwards under the action of the acceleration, until the brass blades staples were made to grip the lower groove (named arming groove). After this step the fuze was armed but still safe since the primer cap was held in bottom position under the combined action of the acceleration and the intermediate spring, out of range of the percussion pin.

At the muzzle exit the acceleration stopped and the springs could act again : the strong percussion head spring was pushing back the percussion head and the rod forwards, putting again the percussion pin at longer distance from the primer cap. In the same time, the intermediate spring was pushing the mibile block forwards, with the brass blades staples blocked in the lower arming groove. In this configuration and with the intermediate spring neutralzed by the arming sequence, a third spring, of moderate force and located located between the bottom of the primer mobile primer cap block and the fuze tail end, was finally able to act and was pushing forwards the primer position that was now reachable by the percussion pin, hopefully kept in up position by the strong percussion spring.

At the impact, the percussion head was violently pushed back, compressing the strong percussion spring and projecting the percussion pin at the contact of the primer cap in upper position, whose flame was provoking the detonator explosion.

This fuze was mainly in use with the shells of the
  • 75 mm Mle 1897 fieldgun (high explosive shells Mle 1917)
  • 81 mm Stokes mortars
The RY instantaneous fuze correct functionning was entirely dependant of the relative force of the three springs described above. It presented a specific risk at the muzzel exit after the arming and when the primer mobile block was pushed forwards, if the percussion hea was not pushed in up position quicj=k enough for some reason (for instance under the air pressure action for too high shell speeds). It was also the cause of many fatalities when used with the projectiles of the 81 mm Stokes trench mortars when the servants were mistakenly introducing a second shell in the tube before the first one was gone or this one failed to depart.

The head of the usual quick action type of these fuzes was painted in red. Very small quantitities of delayed versions were produced with either a 0,05 seconds integrated delay (fuze head painted in black) for transforming it into a classical percussion fuze, or a longer 0,15 seconds integrated delay (fuze head painted in black and tail detonator painted in violet).


24/31 model 1917 instantaneous fuze. Note the red paint traces under the tin hat (disappeared), showing a classical instanteous fuze (without delay)
24/31 model 1917 instantaneous fuze. Zoom on the hollow percussion push button head
24/31 model 1917 instantaneous fuze. On this one, the percussion head button has lost its upper wall, revealing its hollow structure. At its bottom, the top of the percussion rod can be seen.
24/31 model 1917 instantaneous fuze. Lateral view of a fuze without its percussion head, associated with the classical French tail detonator
24/31 model 1917 instantaneous fuze. Rear view showing the rear extremity of the primer cap cylindrical mobile block
24/31 model 1917 instantaneous fuze. Rear view of another item having lost its primer cap cylindrical mobile block and revealing the tip of the percussion pin at the center
24/31 model 1917 instantaneous fuze. Thos one has been observed in Champagne and is still mounted on a steel shell ogive adaptator remnant
24/31 model 1917 instantaneous fuze. Wartime scheme, at rest configuration



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24/31 model 1918 RYG fuze
24/31 mm model 1918 instantaneous percussion fuze with detonator, system Remondy-Gaba

In 1918 the 24/31 Mle 17 RY fuze was given several internal and external modifications that gave birth to a new device, the 24/31 model 1918 RYG (système RemondY - Gaba) instantaneous fuze.

The fuze was keeping its RY Mle 1917 predecessor Remondy arming and percussion mechanisms, with the percussion push-button head linked to a long percussion rod, the tubular primer cap mobile block with twon machines grooves, the safety mobile cylinder with brass staple. However, the fuze body was shorter, and several modifications were introduced :
  • the percussion push-button at the top of the fuze had a mushroom profile, allowing more non-orthogonal impact angles,
  • a shearable safety pin in brass was inserted transversally through the hollow percussion push-button body, preventing any movement back from the head before the impact, solving the problem encountered by the RY Mle 1917 with in-barrel explosions when two rounds were mistakenly introduced by the muzzle into the stokes mortars, or gun muzzle explosions when the wind pressure was pushing back the button
  • the primer cap mobile block was allowed to move forward much further at the impact, in order to go at the encounter of the percussion pin rod, increasing noticeabily the quick action properties of the device. It was said that it was working by push-back and inertia at percussion

These succesful changes gave the RYG Mle 1918 fuze a real improvement of its use safety, of its quick action properties, and the simplicity of its manufacturing. These qualities are tyhe reason of the long life of this fuze, born in 1918, and used by the French Army between WW1 and WW2 after some minor evolutions, equipping many French shells in 1940, then built for the German Army between 1940 and 1940, and still in use many years after 1945 in a new version made in a light alloy.

Variants with a small delay or a long delay were also built, with a colour code on the upper body (no paint for non delayed fuzes, black paint for short delay, or black paint and viole paint on the tail detonator for long delays). In the delayed versions the percussion rod was also much shorter, the primer cap being this time located at the upper end of the primer cap mobile block while the delay was placed in its lower end.

Initial models were having a classical tail detonator with a female thread. From 1924, new models with a male-threaded detonator were introduced (for artillery only) and named 'light-tailed' variant.

As for the Remony fuze, the use with very high initial shell speed guns was prohibited (> 800 m/s from 1925), or the fuze had to be coverd under a false ogive head preventing the air pressur to act in flight and push the percussion button back.

This fuze was mainly in use with the high explosive shells of the :
  • 65 mm Mle 1906 mountain guns
  • 75 mm Mle 1897 fieldguns
  • 105 mm Mle 1913 fieldguns
  • 155 mm Mle 1917 howitzers
  • 81 mm Stokes mortars


24/31 model 1918 RYG fuze.
24/31 model 1918 RYG fuze. Rear view showing the male-threaded tail detonator, proving this one is not an early version
24/31 model 1918 RYG fuze. Markings : '24 31 RYG / Mle 1918 / CN 5M-35'
24/31 model 1918 RYG fuze. Male threaded detonator removed
24/31 model 1918 RYG fuze. This item percussion mushroom is in perfect condition. Notice the shear pin at the top of the body
24/31 model 1918 RYG fuzes. The two models on the picture are identical
24/31 model 1918 RYG fuze. Top view
24/31 model 1918 RYG fuze. Zoom on the percussion mushroom shaped push button, made in aluminium and much corroded
24/31 model 1918 RYG fuze. Wartime of an early model (with female-threaded tail detonator)



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24 Model 1918 shortened ITR fuze
24 mm shortened ITR fuze with detonator, model 1918 for trench mortars, system Remondy

The 24 mm I.T. Mle 1915 fuze for trench mortar was subjct in 1917 to a major evolution, with the apparition of the new 24 mm 'I.T.R.' Mle 1917 fuze for trench mortar ('R' as 'Remondy'). Externally very similar to the Mle 1915 profile with its long steel stem and the percussion push-button at its top, it was equipped in the inside with a totally new mechanism much more sophisticated : replacing the very basic percussion mechanism with shearable pin safety, a 2-steps arming system of the Remondy type (first introduced sith the RY Mle 1917) was integrated with some modifications, some of them being later used in the RYG Mle 1918 fuze

Just as in this latter, the Remondy mechanism whose principle was based on the actions of 3 springs of different forces and inertia blocks under the effects of the shot inertia, was secured by a shearable safety pin that was cut at impact. Also, the rear wall retaining the strong percussion spring was mobile so that it was allowing the whole primer cap mobile block to run at the encounter of the descending percussion pin at the impact, noticeabily improving the quick-action properties of the device.

Another important inner difference with the 'I.T. Mle 1915' fuze was found inside the long steel stem, where the long percussion rod guided by a wooben cylinder was replaced by a much shorter percussion rod on top of which a solid cyliner (in wood, aluminium or synthetic ivory) was superposed. At rest, the head was protected by a thin tin cap painted in red that had to be removed before use.

The I.T.R. Mle 1917 fuze was mainly in use with the projectiles of the
  • 58T n°2 trench mortars
  • 150T Batignolles trench mortars
In 1918 a new version was introduced with the 24 mm 'I.T.R.' Mle 1918 shortened fuze for trench mortar ('R' as 'Remondy'). This time this version was intergrating more external changes than internal ones. Externally, it looked like a 'I.T.R.' Mle 1918 whose long steel stem would have been amputated by 3/4th of its length, and equipped with a brass cylindrical percussion push-button showing a hole for the percussion rod fixation. In the inside, it was keeping the same mechanism than the one of the I.T.R. Mle 1917 at some rare exceptions including the absence of any security shearing pin and of the solid cylinder between the percussion rod and the percussion button.

Like the preceeding model, this fuze was not manufactured in a delayed version, and it was protected by a thin tin cap painted in red that had to be removed before use.

Only the shortened I.T.R. fuze Mle 1918 survived the war : between WW1 and WW2 and in 1940, it was used with the projectiles of the
  • 75T Jouhandeau-Deslandres trench mortars
  • 150T trench mortars


24 Model 1918 I.T.R. shortened fuze.
24 Model 1918 I.T.R. shortened fuze. Profile view, a so short length instantaneous fuze, but compensated by a super-quick instant percussion system.
24 Model 1918 I.T.R. shortened fuze. Top view with the brass push-button and the hole for the attachment of the percussion rod.
24 Model 1918 I.T.R. shortened fuze. View from below, with the detonator removed.
24 Model 1917 I.T.R. fuze. Modern scheme of the 1917 model
224 Model 1918 I.T.R. shortened fuze. Modern scheme of the 1918 shortened variant



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Time, or time and percussion fuses


25/38 Mod 1880 time and percussion fuze
25/38 mm model 1880 time and percussion field fuze without detonator, system Budin

After 1875, the barrel pyrotechnic system (or 'tubular time fuzes system') is the French technological choice for the time fuzes. It represents a fundamental change versus the principles of the XVIIIth century first wooden time fuzes that preceeded the metal polygonal panel uzes used during the l870 Franco-Prussioan war (2, 3, 4 and 6 flight duration Desmarest fuzes Mle 1859 to 1870 of different dimensions), the 2 and 4 flight duration Maucourant dual fuzes Mle 1869 and finally the 30mm Mle 1874 Henriet dual fuze. It remained the French choice until the 1950's.

The tubular time fuzes were based on common characteristics :
  • a lead stretched tube containing compressed gunpowder and wrapped in spiral around a hollow soft metal tronconic barrel (or 'cylinder'),
  • a inertia concuting system (or 'time pellet') located inside the hollow barrel and designed to ignite the time system gunpowder track at the shot departure,
  • a brass hat, lying over the spiral and pinned with graduated vents around the fuzing tube path,
  • and a gunpowder room located under the barrel and linked to the lower extremity of the fuzing tube.
The setting of the fuzing time of the tubular time fuzes was made by punching the tube and the barrel through the desired graduated hole in the hat. This action determined the spiral exact location that was ignited at shot departure by the inner concutor, and therefore the needed time before the combustion reached the gunpowder room.

This new system was adapeted on a body of a 25/38 Mle 1875 percussion fuze and keeping its Budin percussion system to become the reglementary new time and percussion French fuze named 25/38 Mod 1880 time and percussion fuze. Its brass hat was graduated from 0 to 22 seconds, with a pre-drilled hole every second (but for the nr 21 hole). For a finer time setting the hat could be rotated some degrees around a small scale graduated from 0 to 10.

Some model did not have this fine time setting scale. They were called static hat fuzes in opposition to the fuzes equipped with, named mobile hat fuzes.

It seems that the very fuzes of this type appeared even sooner around 1878, as indicated by one of the items pictured on this page, but I do not have any information on this model that might have been named 25/38 Mle 1878 time and percussion fuze. Some little external differences are separating it from the reglementary fuze Mle 1880 : the tail with the percussion system is a little shorter, the time system base disc is thinner, the pre-drilled hat graduated holes are more oval, and the hole Nr 21 is open.

The 25/38 Mle 1880 fuze being equipped with a Budin percussion system that could only be armed with high initial accelerations, it was denominated 'field artillery fuze' and was mainly in use with the projectiles of the
  • 80 mm Mle 1877 (de Bange) cavalry guns
  • 90 mm Mle 1877 (de Bange) fieldguns
  • 95 mm Mle 1875/1888 (Lahitolle) fieldguns
  • and seemingly some siege, fortress or coast weapons
Adaptator rings couls be added to the original 25mm tail thread in order to use the fuze with shells of different head threads, for instance 35 mm.

We have to mention the Budin percussion system was also used on more voluminous fuzes such as the 30/55 mm Mle 1880 time and percussion fuze (Budin) that was arming the 22 cm shrapnell shells, and in some cases the 155 mm shrapnell shells. One of these fuzes can be observed in the Draguignan Artillery Museum.


25/38 Mle 1880 time and percussion fuze.
25/38 Mle 1880 time and percussion fuze. This obsolete fuze was probably not used in WW1 or only with old ammunition stocks of old guns requisitionned at the war start. Notice on the base the additionnal 0 to 10 scale fine setting that was only used with the mobile hat models.
25/38 Mle 1880 time and percussion fuze. This item has been cut though for instruction purposes and expose its mechanism.
25/38 Mle 1880 time and percussion fuze. The opened time part shows the spiralled fuzing tube wrapped over the tronconic barrel under the graduated hat, La partie fusante ouverte montre sous le chapeau gradué le barillet spiralé, and in the center of the barral the concuting system for ignition.
25/38 Mle 1880 time and percussion fuze. The Budun system percussion system is housed inside the fuze tail axis.
25/38 Mle 1880 time and percussion fuze. Top view of two items. The one at left is marked '80' and is therefore a Mle 1880 reglementary model. The one at the right is marked '78'. Hence it cannot be a model 1880...
25/38 Mle 1880 time and percussion fuze. Mle 1880 (at left) and supposingly Mle 1878 (at right). Notice the little external differences mentionned in the description.
25/38 Mle 1880 time and percussion fuze. Top view, marking '80'
25/38 Mle 1880 time and percussion fuze. Wartime scheme
25/38 Mle 1880 time and percussion fuze. with thread adaptator to tranform the fuze into a 35/38 Mle 1880. Picture shot at the Artillery Museum at Draguignan
30/55 Mle 1880 time and percussion fuze. Picture taken at the Draguignan Artillery Museum of a rare first generation barrel fuze using the same Budin percussion system but on a heavier 30/55 mm threaded body.



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40/55 Mle 1880, 25/38 Mle 1881 and 30/55 Mle 1882 time and percussion fuze
40/55 mm model 1880, 25/38 mm Model 1881, 30/55 mm Model 1882 time and percussion siege fuze, without detonator, system Siège et Montagne ('S.M.')

The 25/38 Mod 1880 time and percussion fuze, that was derivating from the 25/38 Mle 1875 percussion fuze (system Budin) could only be armed with high initial accelerations more often fonund in the field artillery weapons, it was therefore necessary to design specific systems that could be armed with the lower initial accelerations of the siege and heavy artillery. This is why the percussion system of the 25/38, 30/45 and 40/55 Mle 1878-81 and 1878-92 percussion fuzes (system Siège et Montagne) was also used for the creation of a 40/55 mm Mle 1880 siege time and percussion fuze, adapted to the thread size and the initial speeds of the heavy artillery.

With is mass ans size greater than the ones of the 25/38 Mle 1880 fuze, this new one also had a longer spiral tube allowing longer combustion times. Consequently its hat was graduated from 0 to 30 seconds. As for the previous fuze ogf the 'mobile hat' type, a graduated scale on the fuze base allowed a fine tuning at 1/10th of a second by rotating the hat. There was no such fuze with a static hat and no scale.

The 40/55 Mle 1880 time and percussion fuze was mainly in use with the projectiles of the
  • 120 mm Mle 1878 (de Bange) guns
  • 150 mm Mle 1877 (de Bange) guns
The Siège et Montagne percussion system was also used in this first generation tubular time and percussion fuzes with sevearl other sizes and threads, in the 25/38 Mle 1881 time and percussion fuze (with a similar shape to the one of the 25/38 Mle 1880 system Budin fuze, and graduated from 0 to 22 secondes only)and the 30/55 Mle 1882 time and percussion fuze.


40/55 Mle 1880 time and percussion fuze. This item was damaged by the impact and its hat is deformed.
40/55 Mle 1880 time and percussion fuze. The fuze tail length is typical to the Siege and Mountain percussion system.
40/55 Mle 1880 time and percussion fuze. Rear view on the long tail housing the Siège et Montagne percussion system, identical to the purely percussion fuzes of this system. This one item tail end hole is typical of the S&M percussion fuzes Mle 1878/81.
40/55 Mle 1880 time and percussion fuze. View of the mobile hat drilled with 30 holes, and the 10 base graduations for the fine tuning by rotation.
40/55 Mle 1880 time and percussion fuze. Cut-though pictured in the Draguignan Artillery Museum, exposing the Siège et Montagne percussion system in the tail.



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25/38 Mle 1880/85 time and percussion fuze
25/38 mm model 1880/85 field fuze, system Budin

In 1885 a new version of the first French tubular fuze (25/38 Mod 1880 time and percussion fuze, system Budin) appeared. .

This new 25/38 Mle 1880/85 time and percussion fuze was still equipped with the Budin percusioon system. But major differences were introduced on the hat : still graduated from 0 to 22 seconds, it was now always static, the fine time setting between the pre-drilled holes was obtained by smaller drilled holes for the 1/2 seconds, and the hat could be punched by the servants on intermediate graduations around the spiral.

This hat new design wil be used from than for the folloxing French tubular time fuzes, the mobile hat being definitively abandoned.

The 25/38mm Mle 1880/85 time and percussion fuze was most probably used with the same projectiles that the equivalent Mle 1880.


25/38 Mle 1880/85 time and percussion fuze.
25/38 Mle 1880/85 time and percussion fuze. At left for comparing the 30/38 Mle 1884 that was more widely used, with a similar hat shape.
25/38 Mle 1880/85 time and percussion fuze. Rear view with the tail containing the Budin percussion system
25/38 Mle 1880/85 time and percussion fuze. Top view - markings '2 - 85'.



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25/38 Mle 1881/85 time and percussion fuze
25/38 mm model 1881/85 time and percussion siege fuze, system Siège et Montagne

The 'old' French 25/38 mm Mle 1881 time and percussion siege fuze, system Siège et Montagne was given in 1885 the same improvement as the one given to the 25/38 Mod 1880/85 time and percussion fuze, with the apparition of a static hat marked with intermediate graduations between the seconds and 1/2 seconds pre-drilled holes, still graduated from 0 to 22 seconds.

As for most of the French fuzes the tail thread of this 25/38mm Mle 1881/85 time and percussion siege fuze(Siège et Montagne) could be modified with an adaptator to make it compatible with shell holes > 25 mm diameter.

The 25/38mm Mle 1881/85 time and percussion fuze was most likely used with the same projectiles than the equivalent fuze Mle 1881.


25/38 Mle 1881/85 time and percussion fuze. Markings 'ECPR 402 - 2-91 - SM'.
25/38 Mle 1881/85 time and percussion fuze. The tail length is typical of the Siège et Montagne percussion system.
25/38 Mle 1881/85 time and percussion fuze. Comparaison with the 30/38 Mle 1884 that was more frequently used, and its similar hat profile.
25/38 Mle 1881/85 time and percussion fuze. Rear view on the long tail housing the Siège et Montagne percussion system



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30/38 Model 1884 and 1884 T tiùe and percussion field fuze
30/38 mm model 1884 and 1884 T time and percussion field fuze without detonator, system Saussier

The first tubular time and percussion French fuzes were not compatible with the entire range of guns, because of the percussion systems sensitivity to initial accelerations of the shells. Therefore two specialized fuzes systems had to be used : Budin system based fuzes for the fieldguns with high initial speed projectiles, or Siège et Montagne system based fuzes for the siege artillery projectiles.

In 1884 a new time and percussion fuze was proposed with a percussion system that was compatible with all this period types of projectiles and weapons. The30/38 mm Mle 1884 time and percussion field fuze was then composed with : This new Saussier syetem was composed with :
  • a static percussion pin located at the top of the percussion system room,
  • a mobile primer cap inertia block locked at rest in low position by an arming spring and machined with external grooves in its lower section,
  • a mobile safety inertia block equipped with brass blades staples and locked at rest on a top position by the same arming spring,
  • a weak internal safety spring introduced between the safety inertia block and the percussion pin.
At rest, the Saussier percussion system was secured by the mobile safty inertia block and the arming spring, that were preventing any contact between the primer cap and the percussion pin.

At the shot departure inside the barrel, the safety inertia block was forced backwards and compressed the safety pring. Its staples were gripping the grooves machined in the lower part of the primer cap mobile inertia block, locking the whole system in armed condition.

In flight, only the small safety spring over the mobile safety block was preventing the contact between the primer cap and the static percussion pin. If the time system was triggered after the given preset flight time meanwhile, its flame was communicated to the percussion system room and ignited the primer cap.

At the impact, the now consolidated assembly of the safety inertia mobile block and the primer cap inertia mobile block was projected frontwards, compressing the weak top safety spring, so that the primer cap was hitting the static percussion pin.

This fuze was adopted in 1885 and was able to by used with both fieldguns and siege artillery weapons, under full or reduced propulsive charges, por impact or time shots fire. It replaced progressively the former models and became the reglementary time and percussion fuze.

A l'impact, l'ensemble solidaire pièce de sûreté / porte-amorce était projeté vers l'avant en comprimant le faible ressort de sûreté et l'amorce venait heurter le rugueux.

Cette fusée adoptée en 1885 fonctionnait avec les canons de campagne et de siège, sous charges propulsives entièrres ou réduites, pour des tirs fusants ou percutants. Elle remplaça progressivement les modèles plus anciens et devint réglementaire.

Although compatible with a wide range of other weapons, it was mainly used with the projectiles of the :
  • 80 mm fieldguns
  • 90 mm fieldguns
  • 95 mm fieldguns
In 1902 this fuze was modified in order to allow its time setting with the "débouchoir double" machine, quicker and safer than the human action for drilling the appropriate hole in the hat, by adding a stud at the tronconic hat base, becoming the '30/38 mod 84 T time and percussion field fuze'.

From this date and during the whole length of WW1, it was mainly in use with the shrapnell shells of the :
  • 80 mm fieldguns
  • 90 mm fieldguns
  • 95 mm fieldguns
  • 120 mm fieldguns
It has to be mentioned that the Marine adopted this fuze plan in 1889 replacing the Saussier percussion system with a new Robin percussion system initially used in the 17.5/28.5 Mle 1886 time and percussion fuze for 65 mm shells, making it a 0/38 Mle 1886/89 (T) time and percussion fuze for 90 mm and 10 cm shells. They were progressively replaced by the Army 30/38 Mle 1884 (T) time and ercussion fuzes.


30/38 Mod 1884 time and percussion fuze. Markings '2-87'. This is an original model without stud
30/38 Mod 1884 time and percussion fuze. Both items are dated 1887.
30/38 Mod 1884 time and percussion fuze. Rear view. The left fuze percussion system has been ejected by the burst
30/38 Mod 1884 time and percussion fuze. The observation shows noticeable differences between these two items. The left one is equipped with a lateral plug and is therefore rather a 1884T model (although the hat is dated 1887 and the stud was introduced only in 1902 - olf 1884 fuze modernization ?), while the right one is a stud-free 1884 original model. Moreover the tail thread length is different.
30/38 Mod 1884 time and percussion fuze. Top view of three items. Two of them are marked '3 - 87' et '2 - 87'. The third one has no marks and is a 1884T with a stud
30/38 Mod 1884 time and percussion fuze. Top view. Markings : 'ECP 1 - 04 - 30-38 Mle 84
30/38 Mod 1884 time and percussion fuze. Rear view on the tail plug hiding the Saussier percussion system
30/38 Mod 1884 time and percussion fuze. View on the tail inner room. The percussion system has disappeared, but the percussion pin is still visible, surronded by the vents linked to the time system in the hat
30/38 Mod 1884 time and percussion fuze. Wartime scheme



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30/55 Mod 1889 and 1889 T time and percussion fuze, or time fuze Mod 1913.
30/55 mm time and percussion fuze model 1889 or 1889 T system Saussier without detonator, or time fuze model 1913

The French Marine developped its own time and percussion fuzes from 1886 with the 18/28 Mle 1886 time and percussion fuze for the 65mm shell, équipped with a Robin percussion system, followed in 1889 by a 30/55 Mle 1886/89 time and percussion fuze system Robin for the 14cm and 16cm guns shells.

This fuze was allowing noticeabily longer flight times than the fuzes of the same period, since it was graduated from 0 to 49 seconds instead of the usual 22 or 30 seconds.

The Army adopted in 1889 a fuze with similar dimensions, shapes and properties, but equipped with the Saussier percussion system. This new fuze was called 30/55 mm model 1889 time and percussion fuze. The Marine decided to abandon its original design and adopt the one of the Army in 1901.

In 1902, a lateral stud was added at the tronconic hat base of the Mod 1889 fuze to make it compatible with the mechanical time setting machine ('débouchoir double'). This new version was consequently named 30/55 mm model 1889 T time and percussion fuze.

The fuze tail plug was given an unusual conical shape designed to penetrate more easily into the gunpowder mass of the shell to which the fuze was screwed, with two vents obturated with copper sheets. The 30 mm tail thread could be changed into a 40mm one using an adaptator ring Mod 1889. This long combustion time fuze was mainly used with the shells of the :
  • 105 mm fieldguns (rear charge shrapnell shells)
  • 120 mm guns (shrapnell shells)
  • c155 mm guns (shrapnell and illuminating shells)
A purely time fuze (without percussion system) was developped in 1913, principally for the anti-aircraft artillery, so that a shell that did not exploded in the air would not explode when hitting the ground, usually in friendly territory. While the head of this 30/55 mm model 1913 time fuze without detonator was identical to the one of the 30/55 mm model Mle 1889 time and percussion fuze, its tail was of course much shorter, filled with gunpowder instead of the percussion system, and closed by a flat plug.

This variant was mainly in use with the shells of the :
  • 75 mm anti-aircraft guns (rear charge or mixed charge shrapnell shells, tracer shells)
  • 105 mm guns (tracer shells).


30/55 Mod 1889 T time and percussion fuze. Markings 'INERTE', probably for instruction purposes. Model with a plug
30/55 Mod 1889 T time and percussion fuze. Piece bought on flea market, this view shows the setting of the time system with a punch made at the graduation '23 secondes'
30/55 Mod 1889 T time and percussion fuze. Another item showing the flight time set to '21 secondes'
30/55 Mod 1913 time fuze. Detail of the hole for the filling of the gunpowder room, plugged with a screw
.
30/55 Mod 1913 time fuze. This one has been observed in Champagne, on a 75 mm shrapnell shell ogive. No markings but is is certainly a 1913 time only fuze (no percussion pin in the tail, mounted on a typical 75 mm shrapnell AA shell)
30/55 Mod 1889 time and percussion fuze. Initial model without stud, markings '30/55 - ECP 1 - 03 - Mle 89'
30/55 Mod 1889 T time and percussion fuze. Disassembled item showing the lead inner spiralled track and the central tronconic part hosting the concuting system
30/55 Mod 1889 T time and percussion fuze. View from below showing the vents made to ignite the shell charge from the time system, and the percussion pin of this time and percussion version. Picture by Luc Malchair
30/55 Mod 1913 time fuze. View from below showing the vents made to ignite the shell charge from the time system, and the lack of percussion pin of this purely time version.
30/55 Mod 1889 time and percussion fuze. Cut-through photographed in the Artillery Museum in Draguignan
30/55 Mod 1889 T time and percussion fuze. View on the tail housing the Saussier percussion system, with is conical plug and the vents for communicating the flame to the shell charge
30/55 Mod 1889 time and percussion fuze. Wartime scheme



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40/55 Mod 1880/93 time and percussion fuze.
40/55 mm model 1880 modified 1893 time and percussion fuze without detonator, system Siège et Montagne..

The old 40/55 Mle 1880 time and percussion fuze equipped with a 'Siege et Montagne percussion system' was modernized in 1893, by the adoption of the classical non-rotating heads of the 30/55 Mle 1889 time and percussion fuze.

Just as this latter, it was including a spiral fusing tube in a hat graduated from 0 to 49 seconds, but was keeping its Siege en Montagne percussion system (giving to their tail a unusual length) instead of the Saussier one, probably in order to use this fuze with very low initial speed shells.

This new device took the name 40/55 mm mod 1880/93 time and percussion fuze without detonator. Very little information is known about this version. It seems it has not been used during WW1 or very rarely.


40/55 Mod 1880/93 time and percussion fuze. Markings '40-55 - ECP 94 - Mle 80-M93'.
40/55 Mod 1880/93 time and percussion fuze. This strange piece probably was used for instruction purposes, and fixed on a long steel nail. The 40 mm tail thread has been replaced or covered by a smooth brass section, but the typical long tail of the Siege et Montagne percussion systems is subsisting.
40/55 Mod 1880/93 time and percussion fuze. Graduations from 0 to 49. No stud observed.
40/55 Mod 1880/93 time and percussion fuze. View from behind



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22/31 Mod 1897 time and percussion or Mod 1916 time fuze
22/31 mm modèle 1897 or 1916, time and percussion fuze (system Saussier) or time fuze, without detonator

This 22/31 Mod 1897 time and percussion fuze, based on the typical French tubular spiral type fuzes, was specifically designed at the destination of the rear charge shrapnell shells of the famous 75 mm Mle 1897 fieldgun.

Graduated from 0 to 24 seconds for the time behavior (that was ignited by the concutor housed inside the head axis room), the time flight setting before explosion being chosen by punching a hole on the graduation with the help of a specialised machine named 'débouchoir double'. This machine allowed a much quicker setup of the fuzes before shooting than when this operation was made manually, and therefore an essential part of the incredibly fire rate of the revolutionary 75 French gun. In order to be compatible with it, the fuzes had to be equipped with a reference stud located on the ring at the base of the graduated cone.

The models manufactured after the start of WW1 didn't even had the intermediate graduations between the pre-drilled holes, since reading these marks was unnecessary with the use of te 'débouchoir'.

The percussion systeme of this fuze designed to make the shell explode at impact was a 'Saussier' percussion system. Only meant to communicate the flame to the rear charge of the shell through an axial tube (called 'tulipe'), the fuze was not equipped with a tail detonator.

The 22/31 Mle 1897 time and percussion fuze was mainly in use with the shells of the :
  • 65mm Mle 1906 mountain gun (cast-iron shell mod 1908 and shrapnell shell mod 1908)
  • 75mm Mle 1897 fieldgun (Ordinary shells 1898, rear charge shrapnell shells mod 1897, mixed charge shrapnell shells mod 1897 A and M, incendiary shells mod 1916 G, incendiary shells type G, tear gaz shells with two lead reservoirs, leaflet shells, illuminating shells type Bourget)


In 1916, a purely time variant was introduced similar in shape to the mod 1897, but lacking a percussion system (externally not discernable). Called '22/31 mod 1916 time fuze', it was mainly in use with the shells of the :
  • 65mm Mle 1906 mountain guns (shrapnell shells mod 1908 and mod 1918/1911)
  • 75mm Mle 1897 fieldguns (ordinary shells mod 1898, rear charge shrapnell shells mod 1897, incendiary shells mod 1916 G.)
An elongated time fuze (with markings from 0 to 31 secondes), named '22/31 mm A model 1916 time fuze' ('A' as 'Allongée' - Elongated) was also introduced and used.

The 22/31 fuze, in its 1897 or 1916 versions, is the time or time and percussion fuze that can be observed most frequently nowadays in former batllefields.


22/31 Mod 1897 time or time and percussion fuze.
22/31 Mod 1897 time or time and percussion fuze. Three items observed in Champagne. The first one was punched for a 12,2 seconds time flight before explosion, the third at 17,3 seconds. Notibe the second one deformation under the effect of the landing energy.
22/31 Mod 1897 time or time and percussion fuze. Nice item, a typical artefact observed on former battlefields
22/31 Mod 1897 time or time and percussion fuze. Hat top details. Markings'ECP 10 05' - '22-31 Mle 97'
22/31 Mod 1897 time or time and percussion fuze. This item has been removed from the shell ogive, markings 'ECP 21 01 - 22-31 Mle 97
22/31 Mod 1897 time or time and percussion fuze. Rear view of two items; One of them still has its tail plug
22/31 Mod 1897 time or time and percussion fuze. Sen from the ogive inner side with a view on the fuze vents communicating the flame to the rear charge through the shell axial tube ('tulipe')
22/31 Mod 1897 time or time and percussion fuze. Wartime scheme



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24/31 Mod 1915 or 1916 time or time and percussion fuze
24/31 mm model 1915 or 1916 time or time and percussion fuze with detonator, system Robin

Designed on the basis of a 22/31 Mod 1897 time and percussion fuze, but with a 24 mm tail thread, this fuze filled the need for a detonator-fuze, time and percussion, that was missing within the French material at the beginning of the war (none of the time or time and percussion fuses of that period allowed the addition of a tail detonator for the use with high explosive shells).

Having a detonator coupled to the fuze tail rather than attached to the shells was an advantage, because of the easier ways of keeping the fuzes safe from the weather than the shells.

The fuze tail bottom had a male thread where a detonator (of the same type that the ones used with 24/31 Mod 1899 percussion fuze) could be screwed.

The time apparatus was graduated from 0 to 24 seconds, just like the 22/31 Mod 1897 time and percussion fuze. On the other hand, the Saussier percussion system in the fuse tail was from now on replaced by a a Robin percussion system.

The percussion system was separated from the time system by a shutter, to avoid its accidental activation during the combustion. A short delay of 0,05 seconds wad systematically added to avoid explosions in the gun tube of high-explosive shells equipped with that fuze.

This model, named 24/31mm Mle 1915 time and percussion fuze with detonator, was mainly used with the projectiles of :
  • 65, 75, 90, 105, 120 and 155 mm guns (high explosive shells, with low ranges for the calibers higher than 75 mm)
  • 65 et 75mm (Shrapnell shells Mle 1926)
A strictly time version, of identical shape (and externally really similar) was developped in 1915 just by removing the Robin percussion system from the tail body. That fuze was called the 24/31mm Mle 1915 time fuze with detonator It was used with high explosive anti-aircraft shells (in order to avoid a ground explosion when hitting the ground on friendly territory if the time system was failing).


24/31 Mod 1915/16 time and percussion or time fuze. Rear view of two items, on the side of the detonator thread (for female detonator)
24/31 Mod 1915/16 time and percussion or time fuze. Rear view, no visible markings
24/31 Mod 1915/16 time and percussion or time fuze. Those two identical fuses only differs by the presence of a tin/lead protection cap (to remove before the shot) on one of them
24/31 Mod 1915/16 time and percussion or time fuze. Side view
24/31 Mod 1915/16 time and percussion or time fuze. Wartime scheme



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Time or time and percussion fuse-detonator 24/31 A Mod 1915 or 1916
Time or time and percussion field fuse-detonator 24/31 mm, elongated, modèle 1916 or 1918, system Robin

The increase of the range of the 75 mm field gun, thanks to the use of more aerodynamic shells, made the duration of the time system of the 24/31 Mle 1916 fuse too short for the full trajectory.

Therefore, in 1918 a time and percussion fuse-detonator was designed, elongated by the addition of an additional spire (6 spires instead of 5), graduated from 0 to 31 seconds, named 'Time and percussion fuse-detonator A 24/31 mm Mle 1918', with a 'A' for 'Allongée' ('Elongated'). A Robin-type percussion system was located in the tail.

It is easy to recognize that fuse thanks to the graduations, of course, but also by the thinner cone base, about half the regular one.

A purely tiem model, dedicated to the anti-aircraft fire, having the tail percussion system removed, had been put into service earlier in 1916 : the 'Time fuse-detonator A 24/31 mm Mle 1916'


Time and percussion fuse A 24/31 Mod 1918. Model found in Champagne, with destroyed detonator
Time and percussion fuse A 24/31 Mod 1918. Two models, one of them still being covered by its tin/lead protection cap
Time and percussion fuse A 24/31 Mod 1918. Tin/lead protection cap removed
Time and percussion fuse A 24/31 Mod 1918 and Mod 1916. Notice the cone base height difference between the elongated and regular models
Time and percussion fuse A 24/31 Mod 1918. Wartime scheme



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Time or time and percussion fuse-detonator LD 24/31 Mod 1917 or 1918
Long distance time or time and percussion fuse-detonator 24/31 mm modèle 1917 or 1918, system Robin

The duration of the combustion of the time and percussion fuse-detonator was insufficient for the long ranges of the artillery of higher calibers than the 75 mm (before the 75 mm fielgun range was also upgraded). Consequently, a highly elongated model, with 9 fusing tube revolutions instead of 5, was designed.

That 'Time and percussion fuse-detonator LD 24/31 mm Mle 1917', with 'LD' for 'Longue Distance' ('Long Distance') was graduated from 0 to 51 seconds, and was equipped with a Robin-type percussion system in the tail.

It mainly equipped the projectiles of the :
  • 105, 120 and 155 mm guns (high explosive shells)
This time again, a purely time model was designed in 1918 by the removal of the percussion system from the tail. That 'Time fuse-detonator LD 24/31 mm Mle 1918' was used for the anti-aircrafts fire.


Time and percussion fuse LD 24/31 Mod 1916. Quite an impressive fuse by its length !
Fusée GrZ 92. Détail montrant l'orifice d'échappement des gaz de combustion du grain de poudre de sécurité, enflammé au départ. Orifice encore fermé par la feuille de laiton d'origine
Time and percussion fuse LD 24/31 Mod 1916. Two items, one being covered by a tin/lead protection cap
Time and percussion fuse LD 24/31 Mod 1916. Upper view, with the screw opening the igniting system
Time and percussion fuse LD 24/31 Mod 1916. Dismantled detonator to show the male thread of the fuse tail
Time and percussion fuse LD 24/31 Mod 1916. Upper view of the item still covered by the tin/lead protective cap
Time and percussion fuse LD 24/31 Mod 1916. Wartime scheme



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Time or time and percussion fuse-detonator LDA 24/31 Mod 1918
Increased Long distance time or time and percussion fuse-detonator 24/31 mm modèle 1918, system Robin

To be exhaustive, we need to mention the design in 1918 of a 'Time and percussion fuse-detonator LDA 24/31 mm Mle 1918' (also built in a purely time version), with 'LDA' for 'Longue Distance Allongée' ('Elongated Long Distance').

Having 10 revolutions, and graduated from 0 to 75 seconds, this latter fuse equipped the shells of the heavy artillery, and in particular of the ALGP ('Artillerie Lourde à Grande Puissance' - High Power Heavy Artillery).


Fusée double effet LDA 24/31 Mle 1918 à 10 spires (en bas), comparée à une fusée LD 24/31 Mle 1917 à 9 spires (en haut). Photo Patrice Colin



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Time and percussion fuse-detonator Saint Chamond with two discs

Notable exception to the general use of revoluting fusing tubes for time fuses in France, this Saint Chamond time and percussion 2-discs fuse was using the classical revolving discs system that was generalized in all the other armies. The lower disc was graduated from 1 to 18.

The St Chamond time and percussion fuses were set by using a special apparatus named 'Regloir' ('regloir automatique sur banc a trepied')

It mainly equipped the projectiles of the :
  • 70 mm semi-automatic mountain gun Saint Chamond
  • 75 mm campaign guns of various types Saint Chamond


Time and percussion fuse St Chamond with two discs. Images courtesy Florian Garnier
Time and percussion fuse St Chamond with two discs. One of the rare French fuzes using a revolving discs system
Time and percussion fuse St Chamond with two discs
Time and percussion fuse St Chamond with two discs
Time and percussion fuse St Chamond with two discs, dismantled



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