WW1 FRENCH FUZES GALLERY

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)

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.

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)

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.

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

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 .

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.

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.

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.

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.

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).

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).

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

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

It is certain this antique fuze has not been used during WW1, but it has been included in this section because it is the ancestor of the succeeding French time fuzes.

The very first French time fuzes were made with a simple long wooden tronconic tube whose axis was drilled and filled with a compressed fuzing stuff. The fuze time had to be set before the fuze was inserted inside the shell : before the shot, one needed to drill a hole in the body at a distance corresponding to the desired combustion time (pre-determined thanks to engraved circles ont the body for times between 1 and 24 seconds). The fuze could only be inserted inside the shell then. At the shot departure, the central time channel was ignited from the top by the hot propulsive gasses, and burnt until it reached the drilled hole inside the shell, igniting the shell charge.

In 1859 two new types of time fuzes appeared, in metal and able to be set up after being inserted inside the shell. In the Desmarest time fuzes of the first type, 2 or 4 independant parallel channels filled with different lengths of compressed fuzing material were machined in the tail and were connecting the fuze tail base to the squared section head. It was just needed to punch the leather plug of the chosen channel to select the flight time before explosion (350, 570, 730 and 900 meters for the 4 channels fuses, 1100 and 2000 meters for the 2 channels fuzes).

In the Desmarest time fuzes of the second type, a single fuzing channel was machined in the axis of the fuze tail and was following a circle path inside the head. On each of the 6 lateral sides of this hexagonal nut-shaped head a hole was pre-drilled and obturated with a leather plug. One just head to punch the plug of the hole corresponding to the chosen combustion time on the fuze already inserted inside the shell. Two further evolutions came later based on the same design but with only 4 or 2 holes selectable out of 6.

The Desmarest time fuzes were not very reliable (causing numerous dud shells), and were soon abandoned. A last model was adoopted 10 years later with the Time fuze Mod 1870 system Treille de Beaulieu, before the apparition of the typical French tubular time fuzes (or barrel time fuzes), much more sophisticated and reliable but directly inspired by the principles introduced by the Desmarest time fuzes with the fuzing track whose effective length was selected by punching.

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.

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.

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.

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.

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 :

• a time system inherited from the 25/38 Mod 1880 time and percussion fuze system Budin, with a static hat similar to the one of the 25/38 Mod 1880/85 time and percussion fuzes graduated from 0 to 22 seconds with pre-drilled holes for seconds and 1/2 seconds and marks for 1/10 seconds,
• a brand new percussion system named Saussier system (from its inventor's name) that will also be used later on percussion fuzes (30/38 mm Mle 1887 percussion fuze system Saussier), and that will inspire the famous Robin system born in 1888 and widely used later in both percussion fuzes ( 24/31 Mod 1899/15 percussion fuze system Robin) and time and percussion fuzes ( 24/31 Mod 1915 and Mod 1916 time and percussion fuze system Robin and later 1917 and 1918 fuzes).

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.

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.

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, equipped 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).

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.

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.

In 1914 the French Army did not have any kind of time fuse with detonator able to have a high explosive shell explode during their flight. This kind of fire, already in use in the German artillery, was useful against entrenhed ennemies, or against aircrafts, therefore it was decided to design an evolution of the 22/31 Mod 1897 time and percussion fuze, with a 24 mm tail thread compatible with the high explosive shells and the addition of a small tail detonator identical to the one used with the 24/31 Mod 1899 percussion fuzes with detonator.

The adaptation of a percussion system to the fuze body inspired from the 22/31 Mle 1897 was causing issues, so the first variant to be introduced was in 1915 the 24/31mm Mle 1915 time fuze with detonator. The tail inner room was containing no percussion system. It was in use with high explosive shells for AA fire (the lack of percussion behavior preventing the explosion of a AA shell whose time behavior had failed when it was landing on friendly territory).

The fuze tail end was machined with a male thread allowing to screw a detonator. The time system hat was graduated from 0 to 24 seconds just as the one of the 22/31 Mod 1897 time and percussion fuze. The punching of holes from tye 0 to 2 graduations was made difficult in order to prevent the accidental and catastrophic explosion of the high explosive shells too close to the gun's muzzle out of the barrel.

It was not before 1916 that the time and percussion variant was finally made available. In this one, the percussion system housed in the tail was a Robin system, from now on replacing the usual Saussier system from the older models. The percussion system was isolated from the time system by a shutter, so that it could not be triggered by it. A small 0.05 secods delay was systematically inserted into tail pyrotechnic chain to avoid the shell bursts inside the barrel.

This version was called 24/31mm Mle 1916 time and percussion fuze with detonator, and it was mainly in use with the projectiles of the :

• 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)

The time fuzes are not externally distinguishable nowadays from the time and percussion ones. During the war, the head top screw nut of the time fuzes and the tin protection cap were painted in blue, while the color chosen for the time and percussion systems was the white.

The increase of the range of the 75 mm field gun, needed by the necessity to reach the highest possible altitudes in AA fire, but also thanks to the use of more aerodynamic shells, made the duration of the time system of the 24/31 Mod time fuze Mle 1915 or time and percussion fuze Mle 1916 too short for the full trajectory.

A purely time model, dedicated to the anti-aircraft fire with no percussion system in the tail, first appeared in 1916 : the '24/31 mm A Mle 1916 Time fuze with detonator' with a 'A' for 'allongée' ('Elongated'). This elongation of the spiral track was given by an additional spire (6 spires instead of 5), and the hat was tehrefore graduated from 0 to 31 seconds instead of the 24 seconds max of the previous models. In order to prevent catastrophic explosions of the high explosive shell too close from the gun muzzle, the punching of the holes was only possible from the 5 seconds one. The tin protection and the top nut of the time model were painted in blue.

In 1918 a time and percussion fuze was derivated from this model by inserting a Robin percussion system in the tail and was named '24/31 mm A Mle 1918 time and percussion fuze with detonator'. In this one, a small 0.05 seconds delay was introduced in the pyrotechnic tail chain in order to prevent the high explosive shell explosion in the barrel, potentially destroying the gun and killing the servants. The tin protection of the time and percussion model was painted in white.

It is easy to recognize that fuze thanks to the graduations going up to 31, but also by the thinner cone base, about half thick compared to the previous model.

Despite its increase to 31 seconds, the duration of the combustion of the 24/31 A time Mle 1916 and time and percussion Mle 1918 fuze with detonator was insufficient for the long ranges of the artillery of higher calibers than the 75 mm (and even for the 75 mm fielgun when its range was also upgraded). Consequently, a highly elongated model, with 9 fusing tube revolutions instead of 6, was designed.

That '24/31 mm LS Mle 1917 time and percussion fuze with detonator', with 'LD' for 'Longue Distance' ('Long Distance') was graduated from 0 to 51 seconds instead of the 0 to 31 seconds marks of the 24/31 A fuzes, and was equipped with a Robin-type percussion system in the tail.

It was mainly in use with 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. Its tin protection cap and the top head screwnut were painted in blue, while the color chosen for the time and percussion model tin cap was white.

To be exhaustive, we need to mention the design in 1918 of a '24/31 mm LDA Mle 1918 time and percussion fuze with detonator ' with 'LDA' for 'Longue Distance allongée' ('Elongated Long Distance'). Having 10 revolutions and graduated from 0 to 75 seconds, instead of the 9 spires and the 51 seconds max of the 24/31 LD time Mle 1918 and time and percussion Mle 1917 fuze with detonator version, this device fuse equipped the shells of the heavy artillery, and in particular of the ALGP ('Artillerie Lourde à Grande Puissance' - High Power Heavy Artillery).Their tin protection hat was painted in black with a green band at the base.

It was also built in a purely time version, without any percussion system integrated, and named 24/31 mm LDA Mle 1918 time fuze with detonator. In this case, the tin hat was still painted in black but the base band was blue.

Notable exception to the general use of revoluting fusing tubes for time fuzes in France, this Saint Chamond time and percussion 2-discs fuze 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 fuzes were set by using a special apparatus named 'Regloir' ('regloir automatique sur banc à trepied')

It was mainly in use with the projectiles of the :

• 70 mm semi-automatic mountain gun Saint Chamond
• 75 mm campaign guns of various types Saint Chamond

The Schneider Company in Le Creusot also designed and produced revolving discs time and percussion fuzes for its export markets, including Russia.

The fight against balloons needed the use of special shells capable to ignite the fabric or the gaz of the aircrafts. Therefore, for the incendiary and tracer 37 mm shells, a dedicated very simple fuze was introduced. This 22/24 concussion fuze for 37 mm incendiary and tracer shells type D Mle 1917 of the Navy was a very lean device composed with a concussion system housed inside a brass ogive.

At the shell start in the barrel, a mobile inertia block bearing the percussion pin was propulsed backwards under the effect of the acceleration and the inertia, and compressed a safety spring. The percussion pin was hitting violently a primer cap whose flame was amplified by a compressed gunpowder ring. This was communicating the fire to a rooms made of a tin cylinder opened through the shell steel walls by 3 round windows and containing a wick. The combustion of this wick was acting as a delay that, once consumed, was igniting the shell's inner incendiary charge. The strong flames produced by this charge were projected to the outside of the flying and spinning shell through the 3 round windows during the shell trajectory in the air and hopefully through the balloon envelope.