Category: WW2 French Light Tank Prototypes

France (1939-1940)
Amphibious Light Tank / Tracked Armored Car – 1 Prototype Built

Amphibious tanks were one of various concepts which saw considerable attention and evolution during the interwar era. Much of this attention was initiated by the British Vickers and Carden-Loyd companies, but experimentations on this type of vehicle quickly spread around the world – eventually reaching France.

A first prototype was worked on by the Batignolles-Châtillon company starting in 1935. Designated as DP2, this design did not prove successful, mostly due to issues with exiting the water, weight, and water-proofing. Nonetheless, Batignolles-Châtillon did not give up on designing an amphibious vehicle, resulting in the very mysterious DP3 prototype by 1940.

The Successor of the DP2

The DP2, produced in 1935 and refined on two different occasions in 1936 after disappointing trials (notably a sinking incident during the first floatation trials in March 1936, when the vehicle attempted to leave water), was not a successful vehicle which could be adopted by the French Army. The vehicle’s trace disappeared after poor results in the March-April 1937 trials it was subject to and the vehicle being given to APX’s facilities in Rueil (likely ARL).

However, this would not mark the end of all work on an amphibious tank by Batignolles-Châtillon. It appears that, at some point, likely in 1939, work began on a new amphibious design. It appears to have retained little to nothing from the DP2, having an almost entirely different architecture and suspension design, while also being a larger and heavier vehicle. Designated as the DP3, it appears to have begun its trials at the unfortunately late date of May 1940.

A Highly Mysterious Vehicle

Very little information is known on the DP3. Pretty much the only hard statistics known on the vehicle are that it weighed approximately 15 tonnes. Nonetheless, observation of the vehicle reveals an amphibious tank very different from the DP2 in design.

Though the DP2 was already fairly large for a light amphibious tank with light reconnaissance and cavalry duties in mind, the DP3 appears to have been even larger, with photos of the prototype next to German soldiers showing a fairly sizeable vehicle, higher than a man despite being turretless, as well as being fairly wide and long.

The hull was very different from the one of the DP2. Though the DP3 was also designed with buoyancy in mind, it did away with the bow extending far from the front of the hull, instead stopping not too far in front of the tracks. The vehicle also appears to have had a higher ground clearance which would have given far better performances when crossing obstacles other than water.

These improved crossing capacities are further suggested by the vehicle adopting a new, likely far better suspension design. Instead of the very low suspension of the DP2, the DP3 went with a fairly high track run that encompassed much of the hull. The design of the road wheels suggests Batignolles-Châtillon went with a suspension design fairly similar to the AMX suspension featured on the R40, or the suspension found on the B1 and B1 Bis, featuring a large number (15) of small road wheels per side. Three (one at the rear and two at the front) were independent; these were likely tender wheels. The others were linked together in bogies of two. The rest of the suspension was protected by an armor plate, though it appears the design used a rear-drive sprocket and a front idler wheel. The tracks also appear to have been vastly different and used large track links similar to those found on the B1 and B1 Bis.

Perhaps the most unique aspect of the vehicle would be the location of its armament though. The DP3 appears to have ditched a centrally-mounted turret entirely. Instead, the vehicle features what appear to be round combat chambers to both sides of the hull. What type of armament would be featured in these ‘barbettes’ is unknown, though it likely would have been machine guns. The crew configuration of the DP3 is unknown as well. One may assume it would have a crew of at least four, with a driver, a gunner for each of the combat chambers, and a commander, but this remains pure speculation. The nature of the engine remains unknown as well.

To the Bottom, but not by Accident this Time

The DP3 prototype began undertaking trials in May 1940 – at the same time as the German invasion of France and the Low Countries began. Very little has emerged from these trials – which were likely hastened and interrupted by the invasion – but the vehicle appears to have been more successful than the DP2.

As German forces closed in towards the Nantes region where the DP3 was being tested in early June 1940, the vehicle was purposefully sunk in the Erdre River to prevent the Germans from seizing and potentially using it. A few months later, the vehicle was recovered by the Germans. All known photos of the DP3 date from this time, as can be clearly identified by the presence of water corrosion on it. The further fate of the vehicle is unknown, but it is not known to have survived to this day, and was very likely scrapped.

Conclusion – the Last Pre-War French Amphibious Tank

The DP3 remains one of the most mysterious prototypes present in 1940 France. Very little information has filtered on the vehicle as a whole. Its armament, powerplant, crew configuration, pretty much everything about the vehicle remains unknown, and one may only theorize based on whatever little information and photos of the vehicle remain.

It appears the testers were at least to an extent more satisfied with the vehicle than with the DP2 – and the suspension design indeed appears more mature and allowed for far better crossing capacities. Whether the DP3 had any potential to become a potent combat vehicle remains impossible to judge though.

Batignôlles-Châtillon DP3 Specifications
Weight	~15 tonnes
Suspension	AMX/B1 type
Road wheels	15 per side (three independent, likely tension wheels, 12 in boggies of two)

Sources

Les véhicules blindés Français 1900-1944, Pierre Touzin, EPA editions, 1979
Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions
Char-français

France (1934-1936)
Light Tank – 1 Prototype Built

The armored force of France’s infantry, typically better funded and larger than the cavalry’s, had, during most of the interwar years, the WW1-era Renault FT, the most produced and arguably most successful tank of the First World War (at least, without a doubt, from the French side). An innovative light tank, the FT was produced in massive numbers and, with the adoption of new tanks being slowed down considerably after the end of the Great War, it proved to be the most suitable vehicle for the French military to settle on. By the 1930s though, the old FT had grown obsolete, and timid attempts to produce some somewhat heavier FT-based vehicles had resulted in the NC and D1, which were not built in numbers sufficient to replace or even substantially supplement the FT.

The 1933 light tank specifications

Anticipating a replacement for the FT would soon be requested by the French military, Hotchkiss offered, in June of 1933, their preliminary design for a light infantry tank – by that point a turretless, machine-gun-armed project. Hotchkiss’s proposal ended up as somewhat of a self-fulfilling prophecy, pushing the French army to establish requirements for a new light infantry tank to replace the FT.

Those new requirements were finalized on the 2nd August 1933. Though their formulation was a result of Hotchkiss’s proposal, they would be sent far and wide to French industrialists, with up to 14 different manufacturers working on a design, including some with little to no past experience. Indeed, the role of replacement of the FT, the French Army’s workhorse, would logically lead to massive contracts, as this was no irrelevant vehicle to replace.

The specifications sent to the various manufacturers were quite detailed, with performance requirements in a number of different aspects. The tank was to weigh 6 tonnes, feature a crew of two, and be armed with either one or two 7.5 mm machine-guns, or a 37 mm cannon. The maximum speed should be of 15 to 20 km/h, the armor 30 mm thick, and the vehicle should be able to run for 8 hours and at least 40 km. A large number of mobility requirements were also made, such as being able to climb a 65% slope, be stable laterally on a 60% one, or cross a 1.70 m wide-trench or ford water 1.20 m deep, among others. Generally, the requirements called for a vehicle very similar to the FT in role and capacities – merely updated to take into account some more modern features.

Batignolle-Châtillon enters in the fray

One of the manufacturers which offered a design for the specifications was Batignolles-Châtillon. A subsidiary of the larger Batignolles, Batignolles-Châtillon was installed in Nantes, western France. Formed in 1917 as the Compagnie générale de construction de locomotives Batignolles-Châtillon (Eng: General Locomotive Manufacturing Company Batignolles-Châtillon), the company’s products were mostly linked to locomotive and wagon manufacturing, but already included some military aspects, such as the carriages of railway artillery pieces.

The first ‘Bat-Chat’

During the mid 1930s, Batignolles-Châtillon expanded its operation to include armored vehicles manufacturing, which is not particularly surprising from a locomotive manufacturer. Proposing a vehicle for the 1933 program was an important aspect of this foray into armored vehicles manufacturing, though it was not the only attempt. The company also simultaneously designed an amphibious tank design, the DP2.

As with most manufacturers, Batignolles-Châtillon offered a plan in 1934. A prototype was ordered to the company, which is quite notable. Only five manufacturers got to the prototype manufacturing stage, with the other four, APX, Renault, Hotchkiss, and FCM, being involved in military affairs to a greater extent and since an earlier point than Batignolles-Châtillon. Batignolles-Châtillon’s light infantry tank prototype would be completed in the early spring of 1935 and delivered to the trials commission of Vincennes on the 5th of April that year.

The Batignolles-Châtillon design weighed in at 11.76 tonnes at the prototype stage. It was notable for some of its construction principles, as the vehicle combined cast construction for its turret and riveted construction for the hull. It was the only prototype produced as a result of the 1933 program to use riveted construction. Despite this combination of casting and riveting, the Batignolles-Châtillon prototype is overall more reminiscent of the fully welded FCM design rather than the cast APX, Renault, and Hotchkiss vehicles.

Hull design and construction

The Batignolles-Châtillon’s hull was notable due to its riveted construction. It featured front plates quite considerably angled backward, particularly for the lower hull and front sides. This front lower hull featured two doors from which the driver, sitting in the hull, would enter or leave the vehicle. The upper front hull featured two vision ports, one behind bulletproof glass and another behind a perhaps more solid steel cover. Vision ports under glass were also found on each of the front sides of the hull.

The vehicle’s hull got quite narrower behind the crew compartment, with the engine having a fairly diminutive size. The radiator was located at the rear, with the exhaust on the somewhat angled rear plates. Overall, and unsurprisingly for a riveted design, the hull used very angular shapes, making it comparable to the FCM 36 in this regard, though the Batignolles-Châtillon arguably made use of steeper angles. The precise dimensions of the hull are unknown, and in general little precise data has emerged from Batignolles-Châtillon’s light tank prototype. The armor thickness itself is also not known, though 40 mm (to meet the expected requirements that were updated in 1934) all-around were likely, and realistic considering the vehicle’s weight. The armor of the hull behind the suspension and on top would naturally have been lighter – if compared to other French vehicles of similar role and weight, likely in the 15 – 25 mm range.

Powerplant and suspension

The Batignolles-Châtillon vehicle’s power plant was a 66 hp Unic diesel engine. There are few additional details available, however, this is a quite weak engine for such a heavy vehicle. With a power-to-weight ratio of 5.6 hp/ton, it is quite likely the Batignolles-Châtillon vehicle would have been quite sluggish, with even the quite slow R35 having 8 hp/tonne. Reaching anything higher than the program’s required 20 km/h appears an unlikely feat for the Batignolles-Châtillon tank.

The vehicle’s suspension consisted of seven road wheels, an independent one at the front, and six grouped in three bogies of two each. On top of those bogies were nine triangular mounting points for the side skirts, on which they would be riveted. The drive sprocket was installed at the front and the idler at the rear. In operations, the bogies would be covered by a side skirt, though the road wheels themselves would remain uncovered.

An original one-man turret

The Batignolles-Châtillon design featured a one-man turret armed with a 37 mm SA 18 main gun and a coaxial 7.5 mm MAC 31 machine gun. All of the vehicles in the program would eventually match this armament, although the Renault and Hotchkiss vehicles were first offered either without turrets or with a turret design fitted with two MAC 31s instead.

It should be noted that an armament of two MAC 31s instead of just one is often mentioned, but there do not appear to be any mount for a machine-gun outside of the co-axial one. It is possible this may refer to a backup machine-gun being stored in the vehicle either in case of the mounted one being damaged or having a failure or of the crew having to leave the vehicle. This was common in the French cavalry but rarer in the infantry.

As with the front hull, the turret featured a large number of visors. Glass-covered vision ports were featured on the front of the turret’s forehead’, towering quite considerably in the rear three-quarters of the design, as well as on each side. Smaller vision slots were found on the sides and front sides.

At the rear of the turret, a spring-loaded rectangular door could be found. It would allow the commander to stick out of the turret outside of combat situations, or to evacuate the vehicle in urgency. The commander would enter the vehicle from the front hull hatches, and not the turret door.

The size of the turret ring, while not known, was most likely 875 mm, as with the APX turrets featured on the APX, Hotchkiss, and Renault designs, and the FCM’s welded turrets. Turret interchangeability was a requirement for the 1933’s program turrets. In any case, the Batignolles-Châtillon light tank had a one-man turret, in which the crew member would occupy the roles of commander, gunner, and loader. Even with a lot of intelligent technical solutions, making such a turret ergonomically viable – especially with an armament heavier than machine-guns, even with a gun firing small shells such as the 37 mm SA 18 – was pretty much in the realm of fantasy. The commander would very likely have been very much overtasked in operations – though this is also no different from all other vehicles of the 1933 program, due to all following the requirements of a vehicle featuring 2 crewmen.

Unsuccessful trials in 1935

The Batignolles-Châtillon light infantry tank was trialed in 1935, from the vehicle’s delivery in April of 1935 onward.

The vehicle did feature some interesting aspects. Notable was that the liberal use of glass-covered vision slots by the designers allowed for very good visibility, superior to that of other proposals for the light infantry tank design. The armor was also judged satisfactory, with the exception of the hull armor behind the suspension, though how vulnerable this section of the vehicle’s hull would be in practice is questionable. In terms of performance, the Batignolles-Châtillons did not at all appear to have been inferior to other candidates.

Where the Batignolles-Châtillon light tank failed, though, was in terms of reliability. Mobility trials of the vehicle were quite the failure. On the 24th June 1935, the tank was unable to accomplish a 50 km drive, with a breakdown requiring repairs. The weak engine was likely an important factor in those failures leading to the prototype being returned to its factory, and receiving some considerable modifications to its suspension.

Modifications and new in vain trials

The Batignolles-Châtillon prototype was returned to its factory following the breakdown in late June, and then received an entirely new suspension, likely due to the old one being lackluster – once again not particularly surprising for a newcomer in armored vehicles design.

It returned to trials with idlers and sprockets that may have been slightly larger. However, those are by far the most moderate changes. Instead of seven, the vehicle now had six, larger road wheels of a newer design, with larger outer rims. Those road wheels were installed, two-by-two, on three bogies of a new, more sturdy design. Those featured horizontal and vertical springs allowing for more extensive movements of the road wheels. The vertical springs were located behind the bogie’s outer structure, on which the side skirt would most likely insert. Four classic rounded return rollers were featured.

This modified prototype was trialed in 1936, from the 20th January to the 1st August. In comparison to its first iteration, the new suspension likely improved the vehicle’s mobility. The gearbox also appears to have been more reliable on this modified prototype. However, the significant issue of poor power-to-weight ratio remained unsolved. Even if the Batignolles-Châtillon prototype had been perfect – as perfect as a two-men infantry tank could be – it is unlikely it would have been adopted at this point, with three of the five prototypes presented in the 1933 program, the Hotchkiss (H35), Renault (R35), and FCM (FCM 36) already having been adopted. Adding yet another very similar vehicle would have been redundant. In general, the quite similar FCM 36 appears to have been superior to the Batignolles-Châtillon in most aspects, although also mounting a diesel engine, the one it used offered a better power-to-weight ratio, and its welded construction would have been sturdier and more durable than the Bat-Chat’s riveted hull and cast turret. The main advantage the Batignolles-Châtillon would have had over the FCM would most likely have been vision, which, while not irrelevant, would still be little in comparison to the advantages offered by FCM’s welded design. Therefore, and while Batignolles-Châtillon appears to have attempted to salvage its design by suggesting outfitting the tank with a more powerful engine – the Batignolles-Châtillon light tank would not be adopted.

Conclusion – An unsuccessful but interesting first foray into armored vehicles design

The Batignolles-Châtillon light tank is quite notable in that it was one of the contenders for the replacement of the Renault FT. Though it would be an unlucky competitor to the R35, H35, and FCM 36, it is still notable that Batignolles-Châtillon, a newcomer in armored vehicle design, managed to have their proposal reach the prototype stage, something only a minority of the 14 manufacturers called upon succeeded in.

This unsuccessful first attempt would not result in Batignolles-Châtillon stopping their foray into armored vehicle design. In the late 1930s, they would continue studying amphibious vehicle design, with the DP2 and later DP3 amphibious tanks. The most famous Batignolles-Châtillon designs are not, however, those from the 1930s, but rather, the firm’s proposed vehicles from the 1950s: the Batignolles-Châtillon 12t, an unlucky competitor to the AMX-13, and, most significantly, the 25t, a lightweight medium tank which gathered some considerable online fame in the last decade. It ought to be noted, however, that no Batignolles-Châtillon armored vehicle would be adopted by the French military, the closest being the Batignolle-Châtillon’s powerplant being an inspiration for that of the AMX-30, which would become France’s standard-issue main battle tank in most of the Cold War.

Specifications
Crew	2 (Commander/gunner/loader, Driver)
Armament	1x 37 mm SA 18 main gun, 1x MAC 31 7.5 mm machine gun; perhaps an additional, back-up MAC 31
weight	11.76 tonnes
Engine	66 hp Unic Diesel
Power-to-weight ratio in hp/tonne	5.6
Armor	Most likely 40 mm all-around, lighter behind suspension & on top and bottom

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p48
Char-français.net (http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=692)
Trackstory N°4: R35/R40, Editions du Barbotin, Pascal Danjou
Les véhicules blindés français, 1900-1944, Pierre Touzin
Chars de France, Jean-Gabriel Jeudy

France (1934-1938 or Later)
Light Tank – 1 Prototype

Throughout most of the interwar years, the workhorse of the French army remained the Renault FT light tank. Developed under the direction of Louis Renault and with the support of General Estienne during the First World War, the small, manoeuvrable, and cheap to produce light tank proved very effective in comparison to the larger and sluggish Saint-Chamond and Schneider tanks. By the 1930s though, the FT’s heydays were gone, and innovations in tank design meant the vehicle was rapidly becoming massively obsolete. Though some efforts had been undertaken to update and produce heavier tanks derived from the FT during the 1920s and early 1930s, resulting in the Renault NC and then D1, those were not adopted in massive numbers, with just 160 D1s built for the French military.

The 1933 light tank specifications

Anticipating a replacement for the FT would soon be requested by the French military, Hotchkiss offered, in June of 1933, their preliminary design – by that point a turretless, machine-gun-armed project. Hotchkiss’s proposal ended up as somewhat of a self-fulfilling prophecy, pushing the French army to establish requirements for a new light infantry tank to replace the FT.

Those new requirements were finalized on the 2nd of August 1933. Though their formulation was a result of Hotchkiss’s proposal, they would be sent far and wide across French industrialists, with up to 14 different manufacturers working on a design; indeed, the role of replacement of the FT, the French Army’s workhorse, would logically lead to massive contracts, as this was no irrelevant vehicle to replace.

The specifications sent to the various manufacturers were quite detailed, with performance requirements in a number of different aspects. The tank was to weigh 6 tonnes, feature a crew of two, and be armed with either one or two 7.5 mm machine-guns, or a 37 mm gun. The maximum speed should be of 15 to 20 km/h, the armor 30 mm thick, and the vehicle should be able to run for 8 hours and at least 40 km. A large number of mobility requirements were also made, such as being able to climb a 65% slope, be stable laterally on a 60% side grade, and to cross a 1.70 m wide-trench or ford water 1.20 m deep, among others. Generally, the requirements called for a vehicle very similar to the FT in role and capacities – merely updated to take into account some more modern features.

The state workshop of APX

One of the five manufacturers which went as far as manufacturing a prototype was the Atelier de Construction de Puteaux (ENG: Puteaux Construction Workshop), abbreviated as APX and sometimes known simply as ‘Puteaux’, after the commune they were installed in within Paris’ suburbs. Founded all the way back in 1866, this state-owned workshop mostly worked with artillery and firearms, producing the designs of various engineers and sometimes designing their own. They were not one of the first French manufacturers to get into tank production, though the SA 18 37 mm gun found on the FT was a Puteaux design. During the 1930s, Puteaux would extend their operations into the field of armored vehicles quite considerably; the majority of turrets mounted on French 1930s armored vehicles, from the Panhard 178 to the B1 Bis’, were designed by Puteaux. That being said, their proposal for the 1933 light tank program appears to have been the first tank designed by APX from the ground up.

The APX proposal

APX presented the project for their light infantry tank in February of 1934, and the vehicle’s design is mostly known from the plans that were presented then.

The tank designed by APX was a vehicle quite diminutive in size, with a length of 4.40 m, a width of 1.58 m, and a height of 1.85 m, turret included. As for the ground clearance, it was quite low, at 0.35 m.

The vehicle used cast construction for both the hull and turret. Though the vehicle was small in size, the hull was, in comparison to the other light tanks submitted by other manufacturers, quite bulky. The driver’s compartment is easy to point out, sticking out from the front, and not being angled in the part featuring the vision port – something quite uncommon for cast French tanks. The angled part below featured a large two-piece hatch from which the driver would enter the driving position, which was noticeably low. The armor of the vehicle was 30 mm-thick all-around.

Powerplant and suspension

A somewhat notable feature of APX’s tank was the use of a diesel engine, a feature it shared with FCM’s proposal, which would become the FCM 36. In the case of the APX tank, the engine used was a two-stroke, 4-cylinder engine producing 65 hp at 2,500 rpm. With the weight of the vehicle being 6.85 tonnes, the horsepower-to-weight ratio was 9.5 hp/ton, a decent performance for an infantry support tank; the speed, with 19.8 km/h, was within the expected performances. The engine consumed 7 liters of fuel hourly on average, giving the vehicle a range of 150 km, or about 10 hours, thanks to its 70 liters fuel tanks.

The transmission was installed at the rear, as was the radiator, installed in the sloped, rear part of the engine compartment. The mounting of the transmission led to the drive sprocket being at the rear of the vehicle, and the idler wheel at the front. The suspension consisted of 5 bogies with two road wheels each, the front bogie facing the front and the four others the rear, as well as an independent wheel between the rearmost bogie and the drive sprocket. There were four return rollers at the top. The suspension would, in operation, be covered by a side skirt, which featured openable covers in order to oil and maintain the road wheels. The rear drive sprocket was not covered by this side skirt.

Turret and armament

The APX light tank’s turret is a quite notable one in the history of French turret developments. By December 1933, APX had launched itself into the design of cast turrets, first for the B1 heavy tank, but soon for its own light tank.

The result was a mostly cylindrical turret design, featuring a rounded observation cupola on top, a door at the rear, and a mantlet sticking out at the front. Two vision ports were present, one on each side. The turret was notable for mounting both a 37 mm SA 18 main gun and a 7.5 mm machine-gun – while the program originally requested a vehicle that would have either, but not both. It should be noted the exact model of the 7.5 mm machine-gun which was to be used is not known. While the 7.5 mm MAC31E, which would become the standard French tank machine-gun of the 1930s, appears as the most likely answer, the FM 24/29 light machine-gun has occasionally been mentioned as the vehicle’s secondary armament. It should also be noted that another version of the APX tank, featuring two 7.5 mm machine-guns instead, may have been considered.

The turret was crewed by the commander, who also assumed the roles of gunner and loader. He sat on a retractable seat that rotated along with the turret, though reaching down quite far in the hull’s fighting compartment below. Ammunition for the 37 mm gun was stored on the sides of this combat compartment; the quantity of shells carried is not known.

An elusive prototype, suffering from anti-state bias

It appears that a prototype of the APX light tank was manufactured, being completed in October of 1935. Very little is known about it, and no photographs have survived to this day; it is known the prototype was still in existence by 1938, with a mention of a new oil pump being in construction for the design in a document dated from the 15th of December 1938.

Despite a prototype being manufactured, the APX light tank does not appear to really have been taken into consideration for adoption. APX was the only state-owned manufacturer to go as far as manufacturing a prototype, and this state-owned status appears to have warranted the prototype an ‘out of competition’ status.

It should be noted that the requirements for light infantry tanks were edited in May of 1934, now requesting a 40 mm-thick armor while raising the maximum required weight from 6 to 8 tonnes. It is not known if this change in requirements was considered when manufacturing the prototype.

The influential APX-R turret

While APX’s light tank design as a whole is obscure, its turret is not. It was, in 1935, adopted on both Renault and Hotchkiss’s light tanks, under a version that appears to have undertaken some minor evolutions, but remained vastly similar. This turret would be known under the designation of APX-R; featured on both the Hotchkiss and the Renault light tanks, which would become the two most produced French tanks of the 1930s, it would by far be the most common turret design in the whole of the French military by 1940, and even be refitted with a longer 37 mm SA 38 gun from 1939 onward. This massive borrowing from the APX light tank remains its main legacy, though one could hardly argue for it to be a particularly great one; the APX-R’s one-man design resulted in the commander being utterly overtasked, and even for a one-man turret, it was quite horrendous and inefficient ergonomically.

Conclusion – An APX venture of questionable success

The APX light tank is, in itself, a quite obscure vehicle. An unlucky competitor to the R35, H35 and FCM36, despite seemingly reaching the prototype stage, no photos have been known to survive up to this day. The light tank does not appear to have been seriously considered for the role of standard light infantry tank for the French army either.

Nonetheless, the influence of the design via the APX-R turret ought not to be underestimated – thousands of French tank commanders would, in the later interwar and during the campaign of France, serve in a turret design originally designed for the APX 6-tonnes. As for the prototype itself, its eventual fate is unknown. As often with French pre-1940 French prototypes, the most probable fate of the vehicle was scrapping, though the question remains, by whom; The French prior to 1940, the Germans during the occupations of France, or even the French during the post-war reconstruction era? It appears unlikely an answer to this question will arise anytime soon.

APX Light infantry tank specifications
Dimensions (L-W-H)	4.40 x 1.58 x 1.85 m
Ground clearance	0.35m
Weight	6,850 kg
Engine	2-strokes 4-cylinders diesel engine producing 65 hp at 2,500 rpm
Maximum Speed	19.8 km/h
Power-to-weight ratio (in hp/ton)	9.5
Fuel tanks capacity	70 lites
Average hourly fuel consumption	7 litres
Range	150 km/ 10 hours
Crew	2 (Commander/gunner/loader, Driver)
Armament	1 37 mm SA 18 main gun, 1 7.5 mm machine-gun (either MAC31E or FM 24/29)
Armor	30 mm
Total Production	1

Sources

Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions, p48
Char-français.net
Trackstory N°4: R35/R40, Editions du Barbotin

France (1930s)
Light Tank – None Built

Arguably the most important tank producer during the First World War alongside the United Kingdom, throughout the 1920 and 1930s, France enjoyed a large armor industry which was composed of a considerable number of different manufacturers and designers. These produced various quantities of prototypes as well as designs that never left the drawing board. One of those was the AEM one-man light tank proposal, a project from a lesser-known manufacturer, which never left the drawing board. This was probably a blessing, as the design for the operation of an entire armored vehicle by one crew member was not at all a viable concept.

An obscure design

The one-man light tank is one of two designs which were found in the archives of the DGA (Direction Générale de l’Armament – ENG: General Armament Direction) in Châtellerault, attributed to an obscure manufacturer known as AEM (Atelier d’Études Mécaniques – ENG: Mechanical Studies Workshop). The other sketch corresponds to another quite odd design, a two-man light tank with a particularly low turret and an articulated track design.

The exact date of these sketches is not known, though they are estimated to be from the 1930s. The AEM one-man tank is known by two profile sketches: one showing the vehicle as it would have looked like from the side, and an internal cutaway showing the internal arrangements. It ought to be noted that the one-man tank proposal is sometimes referred to as the “FT Bis” on the internet. This designation, however, is not at all historical and, while the arrangement of the AEM may look superficially similar to the FT, nothing suggests the one-man light tank was in any meaningful way based on Renault’s WW1 light tank.

External design

The AEM light tank was a vehicle of very limited dimensions. Two measurements are featured on the plans which have survived up to this day: the length of the hull, 2.85 m from the front of the hull to the rear of the tail (which was similar in shape to a trench-crossing tail, but was an integral part of the hull, housing the transmission), and the height of the hull, 1.5 m. From these, the height of the turret can also be extrapolated and should be around 0.615 m without the periscope, and 0.77 m including it, giving a height of 2.115 m without the periscope and 2.27 m with it. Including the barrel, the total length of the vehicle should have been about 3.15 m.

The AEM’s turret had a conical section shape with a relatively rounded top from which a periscope stuck out. This shape meant it would likely have been quite wide for such a small vehicle, though the width of the AEM one-man tank remains unknown. This turret featured a vision port on the left side, and would most likely have had the same feature on the right.

The suspension was composed of 13 tiny road wheels, quite similar to the suspension on the much earlier and much heavier FCM 1A and FCM 2C. Two larger wheels were present at the front and rear of the suspension. The drive sprocket appeared to have been featured at the rear, alongside the transmission, while the front wheel would most likely have been a tender wheel. This suspension would be entirely covered by an armored side skirt.

The thickness of the armor which would have been protecting the vehicle is not known, though it would obviously have been very thin and would have unlikely provided protection from anything bigger than a rifle-caliber round.

Internal arrangement

The AEM tank was to be crewed by a single person. He would sit on a seemingly quite elaborate seat for a tank design, mounted just below the turret in the hull. From there, his feet would reach the clutch pedal while his head would reach in the turret. The steering was, as on most vehicles of the era, assured by two levers.

Almost certainly, the turret was armed with a machine gun. That being said, the weapon featured in the sketches does not match either the new 7.5 mm MAC 31E or the old 8 mm Hotchkiss mle 1914 machine guns. Although most of the barrel is covered by a shroud, the tip does not match with either of those designs, and neither does the pistol grip. The heavier Hotchkiss 13.2 mm mle 1930, which would have been quite ambitious in such a small vehicle, does not match either. It is quite likely the machine gun featured in the sketches was purely representative. In this case, considering the design appears to have been dated from the 1930s, the 7.5 mm MAC 31E would have been the most probable choice.

The turret did feature a sight for the machine gun, installed to its left, a periscope that stuck out from the turret’s top, and vision ports on the sides.

The engine was installed just behind the crewman’s seat. There does not appear to be any bulkhead separating the crew and engine sections of the vehicle, a quite archaic feature already after the FT had shown how much of a drastic improvement this was for crew conditions. The model, power, or fuel of this engine is not known. The transmission was installed at the rear, in what appeared similar in shape to a trench-crossing tail, but was an integral part of the AEM tank’s hull.

Conclusion – a terrible design that didn’t go anywhere

The AEM light tank is only known from two sketches. It appears to have never been seriously considered for production, as indicated by the plans not even being properly numbered. This was likely for the best. The operation of a tank, no matter how small, by a single crewman is generally doomed to fail. The amount of attention required to drive a vehicle, observe from the limited vision available from inside an armored vehicle, and operate a weapon, even a machine gun, is far too much to be the task of just one man. During the campaign of France, even two-man tanks such as the R35/40 and H35/39 proved to absolutely overwork their crews, particularly the commander. Not only that but the suspension designed of the AEM tank, seemingly inspired from WW1-era heavy tanks, would most likely not have been able to provide the tank with an adequate speed, while the tank’s tiny dimensions meant it would most likely have struggled to cross many obstacles despite the trench-crossing tail-shaped rear hull. In practice, the vehicle would have been little more than a mobile machine gun with very thin armor and mediocre mobility, while having a more than 2-meters high profile.

The AEM design would not, however, be the last one-man tank offered to the French military, despite the obvious drawbacks of such a design. As late as 1940, engineer Joseph Francois Raymon Collomp would design a one-man tank tasked with minelaying and demining operations as well as armed with a machine gun, tasked by a single crewman in an incredibly uncomfortable lying position. Thankfully, this design would not go anywhere either.

Thanks to MortgageCalculator.uk for supporting the Tank Encyclopedia!

AEM one-man light tank specifications
Lenght	2.85m (without barrel), ~ 3.15m (with barrel, estimated
Height	1.5m (hull), ~2.11m (hull + turret without periscope, estimated), ~2.27m (periscope extended, estimated)
Crew	1
Suspension	FCM 2C-inspired, 13 roadwheels, one tender & one sprocket wheel
Armament	One machine-gun of unknown model
Optics	Periscope, vision ports, machine-gun sight

Sources

Tous les blindés de l’armée française 1914-1940 – Francois Vauvillier – Histoire & Collection editions, p.37
Char-français: http://www.chars-francais.net/2015/index.php/engins-blindes/chars?task=view&id=14

France (1940-1941)
Light Tank – None Built

France has a long history of scientific, technical, military, and cultural achievements. They also have a particularly important place in the evolution of the modern armored vehicle, and in 1940, was the predominant armored power in Europe. A series of well designed and well-protected tanks, such as the Char B1, made up the mainstay of the French armor, forming a potent foe to a potential adversary. In 1940, this was obviously Germany, as France, along with Great Britain, had declared war on Germany in September 1939 following the invasion of Poland. The armored might of France was a serious threat to German plans for the invasion of France, but whilst the Char B had an abundance of armor, there were also designs which, perhaps thankfully, never made it to battle. One of these was from the pen of Joseph Francois Raymon Collomp of Marseilles, and his design for a tiny individual one-man tank was seriously and fundamentally flawed in both concept and design. It never saw action and, whilst even the mighty Char B1 succumbed to the Germans in 1940, the Collomp individual tank succumbed to common sense and was thankfully forgotten in the chaos following the fall of France.

Logic

Collomp started his design ideas with a single piece of logic: the large and modern French tanks were ideal for the large battles, striking deep within enemy territory, but were unsuitable for small actions. These ‘small’ actions would include reconnaissance work, minefield clearance, and providing supporting fire for advancing infantry. In order to reduce losses amongst the infantry forces, Collomp followed the same mental route of many others and conceived of a small armored vehicle capable of protecting the men from small arms fire. Just like those other ideas from ‘push shields’ in WW1, the Italian MIAS, or some hilariously poor ideas from General Martel in Britain, Collomp’s ideas were seriously flawed. He completely ignored the existence of a large number of small tanks already in service in France, including the Hotchkiss H35, Renault R35, and even the rather ancient and obsolete Renault FT from WW1. Instead of considering the use of a vehicle in service, his proposal was unlike anything in use at the time and smaller than any vehicle in service, not much larger than a bathtub, and of about the same combat value.

Internal view of Collomp’s one-man tank design of 1940. The area marked ‘16’ was the hatch to lay mines or charges and the area ‘B’ at the back was the electric motor. The items marked ‘14’ are control switches. Source: French Patent FR867026(A)

The Design

Submitted on 8th January 1940, the design was filed after the declaration of war against Germany but prior to the Battle of France. Overall, the design was a single large ‘cigar’ shape with two tracks running completely around the circumference of the vehicle from front to back. The front and back of the vehicle were curved and the profile was extremely low, as the occupant/s would have to lie prone inside the vehicle on a mattress facing forwards. Operating a forward facing automatic gun (presumably a machine gun), the soldier inside would be in a cripplingly uncomfortable position, especially over rough terrain as the vehicle moved and would be unable to reposition themselves without leaving the limited protection the armor offered.
Just to add an unnecessary layer of complexity to the design, Collomp suggested the addition of both mine-laying and mine-clearing equipment, although the diagram provided with Collomp’s design shows only a single roller held by two arms coming from the vehicle. Presumably, this roller was intended to roll-over and detonate mines, but this would mean it would require a certain amount of mass to simulate a tank and this then adds a weight burden to this tiny machine. All of this weight, the man/men (crew), weapons, steel armor, and now mine roller was to be propelled silently and Collomp planned for an electric motor, adding yet more complexity to the vehicle.
No armor thickness was specified, although, to provide any useful protection from small arms fire, it would need at least 6 mm of protection. Likewise, no performance in terms of speed or range was specified either.
A small hatch was fitted in the front through which the occupant could directly access the soil to lay a mine, although this clearly meant he would have to carry landmines in the vehicle with him. With no space inside in which to turn, this would involve having to drive around laying with his face next to one or more landmines, which is unlikely to have been a popular concept, particularly when facing enemy fire.

External view of Collomp’s one-man tank design of 1940. The area marked ‘6’ was the large hatch on the left-hand side (another was on the right) for access/egress. Of note are the arms and roller for the clearance of landmines. Source: French Patent FR867026(A)

Layout

This diminutive vehicle was planned by Collomp to be just 2.20 m long which, with an estimated length of perhaps 1.70 m allowed for the crew, would mean just 50 cm or so in which to accommodate the electric motor and drives for the tracks. The entire affair was supposed to be not more than 50 cm from the ground to the top of the vehicle which, accounting for the space for the man/men inside, would leave very little ground clearance, meaning the vehicle would get stuck on almost any rock or tree-stump. Further, this very low height would also mean that the crew would barely be able to see over any obstacle, bank, or even long grass.
The tracks, running circumferentially, were fitted with drive wheels at the back and a series of small support rollers around the outside on which the track could run. No information was provided as to how the machine was meant to be steered other than steering switches, which likely meant the ability to vary the driving force delivered to each track causing it to turn. One notable feature though of value for the design was the thought of adding a large hatch in each side of the tank. This meant that, in order to get in or out the soldier would not have to be exposed to enemy fire at all and that, should it overturn, it was so light the soldier could simply right it himself having clambered out the other side.

Top view of Collomp’s one-man tank design of 1940 showing the roller for the clearance of landmines. Source: French Patent FR867026(A)

Illustration of the Collomp 1 to 2-man tank by Mr. C. Ryan, funded by our Patreon Campaign.

---

Crew

The patent drawings show just a single occupant lying prone on a mattress inside, but Collomp specifically mentions that the design could be made wider in order to accommodate a second crewman. This wider version would be even more limited than the single vehicle, as it would still have the same ground clearance but an even greater space between the tracks, making it even less able to traverse even very slight undulations in the ground. The purpose to which this second crew member might be put is not elaborated.
Obviously, a one-man version would leave the hapless soldier the burden of driving (with no indication of how to steer) and firing the weapon, but how this would be divided as tasks for two-men is unknown.

Front view of Collomp’s one-man tank design of 1940 showing the narrow field of fire or vision which would be available to the crew and also the incredibly low ground clearance. Source: French Patent FR867026(A)

Conclusion

The design is awful. For 1940, when there was already a substantial body of tank design work in the public domain, such issues as those created by Collomp’s design should have been both obvious and avoidable. His logic was clear and so was what he was intending in terms of saving the lives of soldiers, but what he created was little more than a premade coffin in which a soldier could became trapped in the mud or on an obstacle or drown in a shallow puddle. With little or no combat value due to no visibility, the vehicle could add nothing to an attack and it is therefore perhaps ironic that the mine clearing suggestion (albeit ignoring the roller) might have been the only realistic use to which the design could have been put. Operating in a straight line through a minefield, the occupant would have easy control and a comfortable lying position without having to tire himself out by crawling and be able to access the dirt in front of him through that hatch to probe for mines and defuse them. Add a mine-tape marker dispenser to the back to show a clear lane through a minefield and this vehicle might have had some utility but, as it was laid out, it is no surprise it saw no production or orders. Whether or not Collomb submitted his design to the military authorities is not known but, with such obvious problems, there was no likelihood that this would ever be added to the Army’s inventory.
If it is any consolation to Collomp, his idea was not even the last of such ‘one-man-prone-tanks’ or even the worst one, but it remains a terrible idea and one which, had it have been in place for 1940, would have added absolutely nothing to the defence of France except perhaps for providing a lot more scrap metal for the Germans. Considering it was submitted in January 1940 though, there would have been no time to have it in time for the Battle of France in May 1940, but it does lay within this ‘Phoney War’ period between the declaration of war and the invasion of France. Almost exactly one year after the fall of France, in June 1941, the patent application from Collomb was accepted by the French patent office under the Vichy Government. It was formally published two and a half months later on 3rd September 1941. A month later, a second patent from Collomp was published for a rotating-cylinder type rifle. He had submitted that one in June 1940, during the Battle for France and whilst that design had more technical merit than his individual tank, it too found no production. What became of Monsieur Collomp is not known.

Collomp’s rotating-cylinder magazine rifle design on 1940. Source: French Patent FR867337(A)

Specifications
Dimensions (L-W-H)	2.2 x .50 x ~.50 meters (1 man), ~1m wide (two man)
Crew	1 man (second crew optional in a wider vehicle)
Propulsion	electric motor – 12 accumulators
Armament	Light Automatic Weapon
Armor	steel, thickness N/A, est. > 6mm
Total Production	None

Sources

French Patent FR867026(A) ‘Chenilette Individuelle’ submitted 8th January 1940. Patent issued 3rd September 1941.
French Patent FR867337(A) Fusil et autres armes de guerre alimentes en munitions par distributeur rotatif submitted 14th June 1940. Patent issued 13th October 1941.