Tromblon Vivien-Bessières

Tromblon Vivien-Bessières

Beginings
As the war progressed into its second year with trench warfare becoming more stagnant on the Western Front and as the use of the hand grenade was becoming one of the choice weapons for both close offensive and defensive tactics, the various belligerent armies found it imperative that they had to develop grenades that could be used at longer distances than that of the hand-thrown types. They at first tried using the regular hand held grenades attached to long steel rods to shoot from the barrels of the rifles but these proved ineffective due to that they had poor aerodynamic stability resulting in poor range and accuracy along with damaging the rifles bore when these were fired.

Rod Grenade
Grenade à main défensive Modèle 1915 Fusante N°1 ... Gr Ma Df 15 F1
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Development
During the early part of 1916 the French military turned to Engineer Captains Jean Vivien and Gustave Bessière to help develop both a grenade and a launching cup that could be used on the various rifles in service. What they came up with was a slip-on launching cup, called a Tromblon, that was made of a block of hardened steel, that had a 50mm (2 inch) bore that was joined to the rifle barrel at the muzzle by a tapered hollow cone. The lower part of the cup is a split socket that slides fairly tight unto the barrel of the rifle, which encloses the front sight and bayonet lugs of the rifle. These tromblons were constructed to fit any rifle, but as some of theses may be a little tight or loose on the barrels it was therefore necessarily advantageous to fit the tromblons that had little or no play to the best suited rifle barrel. The one most important feature of this grenade launcher was the fact that the grenade itself was fired out of the launcher by means of a regulation ball service cartridge and not by a special blank cartridge as had been the case with other grenade launchers in service with the other armies. It was found that the Fusil de Infanterie Modèle 1886 Modifié 1893 dit "Lebel" with its larger bearing area in the receiver and two piece stock could take the beating of the grenade launching better than the Berthier's Fusil de Infanterie Modèle 1907-1915 one piece stock which had a tendency to break in the wrist.

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The Vivien-Bessières system was not the first rifle launched grenade system developed by the French Army as a replacement to the French Rod Grenades based on the British Marten-Hale System which were deemed dangerous. There were two other rifle grenade systems developed, the first was the Feuillette Modèle 1915 developed by Mon. E. Feuillette which was similar to the rod grenade system and was adopted in late 1915. This grenade had a total weight of 410 grams of which 70 grams was cordite. The grenade body was made from iron and was fragmented. The center of the grenade contained a brass tube containing the detonator. The top part consisted of a false aluminum oval shaped head, which increased stability during flight and allowed the grenade to penetrate the sole before exploding. The range of the grenade varied between 80 and 100 meters. These grenades were often carried hanging on the belt or in a special haversack. They are delivered to the front in boxes of 50, disassembled in 3 parts. The second was the Grenade DR Modèle 1916 which was a fairly large rifle grenade with a weight of 550 grams that was made from metal sheeting and consisted out of small fragments on the outside. It was closed with a small wooden plug, which carried the fuse. The lower half of the grenade consisted also out of metal sheeting, but from a much lighter construction and was attached to the grenade body. It contained 4 fins and served as stabilization during flight. This percussion grenade never functioned correctly. It often detonated when fired or did not exploded at all after impacting the target. This was mainly due to a bad design of the fuse. This grenade was used with a cup type launcher called a mandrin. Both of these grenades were powered by a special crimped blank cartridge. Both of these systems were replaced in 1916/17 by the less accurate but more powerful Vivien-Bessières Grenade de Guerre.

Feuillette Modèle 1915
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Grenade DR Modèle 1916
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Grenade de Guerre
The grenade body (A) itself is made of a cast-iron that weighs 415 grams ( .91 lbs. ) and is deeply grooved on the interior into 40 parts in order to insure proper fragmentation. There are two set of machined tubes that run through the body, a central tube (B) which was beveled on the ends for the free passage of the bullet and a lateral tube (C) which houses the detonator (M) and fuze (L). The walls of this tube were made thin at the area that surrounds the detonator (M) to ensure its bursting when it detonated. The tube is carefully reamed at the upper end to a size that will help insure a tight fit with the fuse container (D), the lower portion is tapped to receive the screw plug (G) which holds the detonator (M) in place by means of a soft rubber cup (E). Both of these tubes were made of seamless drawn steel. The fuze container (D) has a hole for the primer (K), a loading hole in the top in which meal and loose powder is inserted and has a vent opposite the primer (K). After the fuze (L) is loaded, the loading hole and vent are plugged with wax plugs (P) to protect the powder. These plugs (P) are blown out by the explosion of the primer (K) which make an ample vent for the gases from the fuze (L) preventing premature bursting of the grenade. The fuze container (D) is machined on the lower end to a size which will allow the upper end of the detonator (M) to fit over it, then it is forced into the lateral tube (C). Under the fuze (L) is placed the striker (H) of which the extremity hangs opposite the primer (K). The striker (H) is made of punched sheet metal. One end of the detonator (M) is left open which this end is entered into the lower end of the lateral tube and overlaps the lower end of the fuze container (D). The rubber cup (E) is placed over the lower end of the detonator (M) and both parts are held in position by the screw plug (G). The arrangement of the detonator (M) at the top and the rubber cup (E) at the bottom prevents the detonator (M) from receiving and shock from the plug end or by being in close contact with the walls of the lateral tube. The grenade is filled through the loading hole (X) with the main explosive charge (N) of 60 grams ( 2.1 oz. ) of either nitrate or chlorate and is closed by a brass screw plug (F). The fuze (L) and brass screw plug (F) was covered by a brass safety cover. These grenades were not painted and after it was filled and weighed they were marked according to the final weight, if it weighed over 490 grams the top of the brass safety device and fuze was painted white and if less than 490 grams they were painted black. Information regarding the manufacturer, type of explosive filler, and designation was painted black or was stamped under the vent in the fuse. A foundry symbol was stamped into the domed portion of the grenade body.
The grenade is launched by the gases produced by the powder of the cartridge which expanded in the barrel then collects in the lower chamber of the discharger exerts pressure on the base of the grenade great enough to propel it forward. The bullet passes through the central tube (B), hits the striker (H), which explodes the primer (K) and ignites the time fuze. The fuze (L) burns anywhere from 5 to 7 1/2 seconds and at the end of the time provokes the detonator (M) to explode, thereby setting off the main explosive charge (N) which in turn allows the grenade body (A) to fragment.

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These grenades were shipped in wooden boxes that held a total of 48 each. Each box was marked with a painted yellow circle that had black lettering which contained the following information in it; Top line: the type of grenade it carried ( V.B. EXP. ) and number contained, Second line: type of explosive, who manufactured the explosive, the Lot number along with the month and year it was manufactured in, Third line: the manufacturer who filled the grenade, the Lot number along with the month and year it was done.

Grenade Mixte
There were two types of grenades that could either be used with the tromblon or thrown by hand called Grenade Mixte (Mixed Grenades). The first was the Grenade Modèle 1916 Type B which had a wide flat bottom with a single band surrounding the bottom body of the grenade and the Grenade Modèle 1917 Df (défensive) which was the same as the Modèle 1916 but had 2 bands surrounding the body. Both of these grenades used the spoon type Billant Modèle 1916 automatic fusing system. The spoon itself fit into the tromblon very easily, when it was prepared to launch, the pin was pulled, a crimped blank cartridge was used to launch the grenade thereby releasing the spoon arming the grenade in flight.

Grenade Modèle 1916 Type B
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Specialty Grenades
There were two different type of specialty grenades that could be used for special applications.
First was the message grenade, called grenade lance-messages or grenade porte-messages, was used to send messages from one trench section to another over heavily engaged areas. These were made from cast iron or steel, the filling plug was made of lead and the fuse housing and shipping cover were made of brass. The body itself was unpainted with a foundry mark placed into the domed portion. These grenades contained a fuze which at the end of the fuzes cycle would detonate a small smoke packet so that it could be found but several problems arose, the first was that the smoke charge was too small, was barely visible and secondly the fuze failed to function in soft ground. A crimped blank cartridge was used with this grenade and was stored in the message container of the grenade. These grenades had a range of 350 meters.

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The flare grenade, called grenade lance-tracts or grenade-signal, was made in two different variations which contained either a red, white or green clusters or stars, with or without parachutes. The Modèle court à étoiles (star short model) measured 108 mm and the Modèle long à parachute (parachute long model) measured 167mm.
The top was closed off with a stamped sheet metal washer/cap showing which color the flare was and the type of signal (cluster or stars) it contained thereby making it easier to identifiy at night. A crimped blank cartridge was used with this grenade which was attached to the top of the flare in a specially made sheet metal holder.

Grenade-signal Modèle long à parachute
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Practice Grenades
There were three different type of practice grenades used for training instruction purposes, the first one was an inert type called the grenade V.B. inerte which was just a hollow grenade body that did not have any of the tubes drilled out or contain any of the explosive materials. The grenade itself was painted gray with a red band around the body. This grenade was used to train the grenadier in the correct loading and firing of the grenades. The next type was called the grenade V.B. amorcées avec détonateur or grenade V.B. lestée-amorcée which only had the lateral tube drilled out for the placement of the detonator on the grenade. This grenade was painted gray with a white and sometimes red and white band around the body. These grenades were shipped in wooden boxes that held a total of 48 each. Each box was marked with a painted red circle that had black lettering which contained the type of grenade it carried ( VB. LEST. ) and number contained. The final type called the grenade V.B. amorcées fumigenes d'instruction was exactly like the previous mentioned grenade but also contained a fuze which at the end of the fuzes cycle would detonate a small smoke packet so that the grenadier could see where his round fell. This grenade was painted gray with blue band around the body. These grenades were shipped in wooden boxes that held a total of 48 each. Each box was marked with a painted blue circle that had black lettering which contained the type of grenade it carried ( VB. INST. ) and number contained. All these grenades used a special developed crimped blank cartridge to launch the grenade.

Accessories
The Tromblon was carried in a special shaped leather holster called an Etui which was normally worn on the waist belt of the grenadier.

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A special sight called the Appareil de pointage et de repérage Modèle 1917 and Modèle 1917 Modifié was developed for use with the tromblon that could used to help verify the angle at which the weapon was fired and aided in determining the approximate range the grenade was to go. The differences between the two different sights was in the range calibrations. The sighting device on the Modèle 1917 Modifié is graduated from 10 meters to eveyy 10 meters until it reached 170 meters. These sights were affixed to the rear sight of the weapon by means of a hand-tightened brass screw.

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Ranges of Grenades
The grenades range was determined by the angle of fire that the trombon was pointed when the grenade fired.

Angle of Fire in Degrees and Range
45 ... 190 meters
50 ... 175 meters
55 ... 170 meters
60 ... 160 meters
65 ... 140 to 150 meters
75 ... 110 to 120 meters
80 ... 85 to 100 meters
85 ... 80 meters
(The numbers are based upon the use of the Balle "D" service bullet loaded with BN3F powder)

Method of Firing
The grenade was normally launched with the rifles butt against the ground in the kneeling position or from either a special firing-rack but could also be used against the hip when standing up or walking. It could be fired from the shoulder but only if the rare circumstance warranted it.
To fire the grenade use the following method:
1. Slip the tromblon on the forward end of the barrel, making sure that you push down on it all the way so that it rests on the muzzle of the barrel on the rifle.
2. Open the bolt of the rifle.
3. Place the grenade base first in the tromblon and make sure that it touches the truncated conical base.
4. Place the weapon on the ground or in the rack with the tromblon facing towards its objective.
5. Load the chamber with a ball service cartridge and then closed the bolt.
6. Verify the range to the target with the sight.
7. Fire the weapon and grenade will be launched from the tromblon.

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Employment
There were 16 Tomblons issued per company which could cover a 200 meter wide front and fire at the extraordinary rate of 150 rounds per minute.

Post-War Usage
In the years following WWI French Ordnance developed a special steel sleeve called a manchon that allowed the Tromblon to be used with the various Mousqueton de Artillerie Modèle 1892 and Mousqueton de Artillerie Modèle Modifié 1916 in service. This sleeve made up the difference in the outside barrel diameter between the two weapons so that the launcher could fit properly. The Tromblon V.B. was also adopted for usage with the latter modified Mousqueton de Artillerie Modèle 1886 Modifié 1893 Raccourci 1935 and new developed Fusil MAS 1936 which was used during WWII and in the wars in both Indochina and Algeria. It is quite possible that many of these were surrendered or captured during the War in Indochina and were used by the Viet-Cong and North Vietnamese Army during the Vietnam War.
Many of the tromblons are still bieng used by the French National Police (Police Nationale, formely called the Sûreté Nationale) and Gendarmerie to launch tear gas grenades for riot contol.

AEF Usage of the V.B.
The American Expeditionary Force ( AEF ) made use of the V.B. system as well.
There were five different types of V.B. Launchers used with the U.S. Service Rifles ...
1. This was the French Tromblon but modified by U.S. Ordnance to fit the service rifles. The lower part and split socket were modified to fit the barrels and front sights of the rifles. French made 50,000 for the U.S.
2. Mark I ... This launcher was the modified type as stated above made by the French ... 50,000 made for the U.S.
3. Mark II ... no information on this launcher ... It was probably a prototype made in the U.S.
4. Mark III ... This launcher was made in the U.S.. These launchers were stamped on the outside to which service rifle they were to be used with. The Rifle, Caliber .30, Model 1917 launcher had a knurled band on them so that the soldier could be sure he had the correct launcher on it during darkness. The Mark III was like the original French launchers.
5. Mark IV ... This launcher had a spiral groove that hooked around the front sight to give it a more positive lock. The Rifle, Caliber .30, Model 1917 still retained the knurled band. This model had a Locking Spring and two Screws that hold the Locking spring to the Tromblon. The smaller or lower end is slotted so that it can receive the part of the barrel that is immediately under the front sight. Just above this slot is another one that will allow the Tromblon to be twisted around the front sight of the weapon. The spring is screwed to one side of the slot in such a manner as to pass under the front sight thereby holding the Tromblon firmly to the weapon.

The U.S. produced grenade was essentially the same as the French one but it was made of malleable iron. The initial American design of U.S. produced VB grenade did not take into consideration the difference between the 8mm and 30.06 projectiles which caused a number of accidents and the initial batches of these American made VB grenades had to be scrapped. They also produced a inert practise grenade called the Grenade, Rifle, Practise, 50mm which vagually resembled a real grenade. These were fired with a special type of cartridge called the CAL. .30, V.B. Grenade Practise Cartridge, M1921. The cartridges were loaded with wooden bullets and Boxer primed cases, this ammunition is often mistaken for blank ammunition and the easiest way to tell it was made for this purpose was the headstamp will marked as follows: FA 22-R, the R indicated that the casehead had undergone a special annealing process to make it harder than the standard service cartridge.
The Tromblon was still bieng used by American and Philipino Troops in the Philipinees during the Invasion of the Philipinees in 1941/42. There is also some mention of them bieng used by the USMC at Guam and Guadacanal.

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US Mark III version for the Rifle, Caliber .30, Model 1917 with U.S. produced VB grenades
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