In 1939, France was on the cusp of a new war with Germany. At the time, many foresaw a return to the static type of attritional warfare of World War One. France was very well set for this type of warfare, with large numbers of well-protected tanks and the formidable Maginot Line on which was hoped to crush any German attack.
The great tank designer and industrialist Louis Renault had been a hero in the First World War with his groundbreaking 2-man FT design. Through the interwar years, his was a magical name in manufacturing and vehicle design, as famous for his cars as for his tanks. It is perhaps odd therefore that, in 1939, with a new war declared against Germany, he submitted a design not so much revolutionary or groundbreaking, but more like a squashed and flattened turretless Char B1. A vehicle with a singular purpose, this was Renault’s plan for a heavily armored and mine-proof tank.
The objective of this proposal was to improve the design of existing tanks in service to make them more resilient to crossing minefields. This would be done by means of adopting both very wide tracks and also by making them run around the outside of the hull. The tracks would be so wide that the pair of them together would occupy not less than half the width of the entire vehicle.
Not only were the tracks to be extremely wide, but they were also to be very thick, with a large pitch, and feature a flange that extended over the wide edges of each link. This served to overlap and provide for a continuously moving armored belt. The drawing provided by M. Renault showed 34 links per side on the tank. The thickness of the track was actually specifically made to match the thickness of the armor on the tank and be made from steel of high hardness. Thus, M. Renault designed the tracks to be part of the actual armor of the tank. The pins connecting each of the links were also to be substantially thicker and heavier than a standard track pin and, thus, these tracks would be resistant to the explosion of any mine the vehicle would drive over.
Suspension for this very heavyweight track would be provided by rows of rollers under the floor and rear part of the tank, with no less than 5 rollers per link. These rollers would be provided with springing in order to provide both shock absorption from a mine blast or from normal travel. An additional roller could be held slung underneath the vehicle, in the narrow space not already covered by the tracks in order to detonate mines. Thus, this vehicle as it moved forwards would clear an entire width through a minefield as it traveled.
The remaining space
The tracks were extremely wide as a percentage of the width of the vehicle, wider perhaps than any other before or since. However, they were not limiting M. Renault’s tank concept. There would still be space in the hull for weaponry and M. Renault took pains to describe what he saw as an improvement over existing designs in this regard. Firstly, mounted centrally on the front in the narrow hull, would be a small ball-type mounting for a light cannon or machine gun. There was another one at the rear. There was obviously insufficient space for a turret. Even the rather small French turrets of the era would be too large and M. Renault proposed a simple cupola for the commander on top instead. In order to provide fire to the sides, another ball mount was placed almost directly above the rearmost point of contact of the track with the ground. Thus, the tank would have at least two machine guns and most likely three, with the rearmost position best suited to a machine gun and the front position to a cannon.
The large boxy interior would provide space for a powerful engine, sufficient to propel this design. M. Renault chose not to suggest any particular type or prospective power output. The engine, judging by the position of the air intakes in his drawings, would be either centrally located – something very awkward for the crew to cope with, as well as noisy and hazardous, or, more likely towards the rear, with a small access tunnel to the rear weapon position. Such a position would mean some ducting for the air intakes to get to the engine for cooling and combustion. However, it was actually divided inside, M. Renault described two chambers, an engine space and a ‘control and combat room’, meaning that, just like his famous FT design of WW1, the engine would be at least separated from the crew space. Drive from the engine to the tracks was provided by drive sprockets at the back.
M. Renault, as would be expected in a patent, provided no exact thicknesses or dimensions of parts or fittings of the design, save for the desire that the tracks be of at least equal thickness to the armor. It is hard to imagine that, in 1939, a man of M. Renault’s experience and capability would not be aware of the German 37 mm anti-tank gun and its capabilities. The British would essentially work off roughly 60 mm of armor as being necessary to protect against that gun’s armor-piercing round. The preeminent French Heavy tank of the era, the Char B1, had only 40 mm and was being improved to a 60 mm standard as the Char B1 bis. It is hard to imagine that anything less than 60 mm would be suitable for such a tank, as it would clearly have to be leading any attack, clearing the mines for following vehicles. Remembering that the tracks were to be equally armored to the hull, this would also mean that the tracks would be around 60 mm thick. Certainly, this would be sufficient to prevent the vehicle from being tracked by a regular anti-tank mine. It would also make for a rather hefty vehicle. The B1 bis was a large tank, over 6 m long, and nearly 3 m high, weighing in at around 31 tonnes. Being smaller than the B1 and bis versions, this vehicle was still carrying very heavy armor for 1939. It is hard to estimate the weight of the vehicle as being anything less than around 25 tonnes.
There was no detail provided as to the number of crewmen which would be needed for this improved tank, but a good estimate can be drawn from the details he outlines. For a start, the tank needed a commander positioned high up in the hull, using the cupola, and a driver located in the front, likely low down. A gunner, positioned higher up, could have operated the cannon. That was at least three crew, but this did not allow for anyone to operate the side or rear machine guns. However, three additional weapons did not mean three additional crew, as the rear-facing machine gun would have little real use to justify a crew member just for that. Just two additional crew might have been needed as gunners, totaling 5 people in the tank.
It is hard to gauge quite what potential a turretless tank might have offered the French Army of 1940. That army already had around 4,000 tanks of various types at its disposal, including the Renault R35 (10.6 tonnes, up to 43 mm of armor, armed with a 37 mm cannon and a single machine gun), the Hotchkiss H35 (11 tonnes, up to 40 mm of armor, armed with a 37 mm cannon and a single machine gun), the venerable 6.5 tonne Renault FT (with up to just 22 mm of armor and either a 37 mm cannon or machine gun), and the impressive 28 tonne Char B1 and B1 bis (with up to 60 mm of armor, a 47 mm gun in a turret ad a 75 mm howitzer in the hull, amongst others). France was well equipped in tank terms, so anything this new and “improved” tank had to offer had to go beyond the plethora of vehicles available.
The ability to drive over a minefield was clearly advantageous in an era where many foresaw warfare returning to some semblance of what was experienced a generation earlier, with heavily protected defensive lines. Other tanks also had the ability to cross and clear minefields with rollers and mine plows designed and able to be fitted to anything from the Renault FT to the Char B and R35.
The timing of M. Renault’s design was to ensure it would go nowhere. France, in company with Great Britain, had declared war on Germany on 3rd September 1939 in response to the invasion of Poland. Perhaps it was this event that spurred M. Renault to think up this design, as it was filed as an application on 21st December 1939. Six months later, however, on 5th June 1940, Operation Fall Rot (Case Red) – the invasion of France – began. At this time, M. Renault was actually in Washington D.C. at the behest of the French government to discuss plans for mass production of tanks with the Americans.
In less than three weeks, the French resistance had collapsed and, on 22nd June 1940, Marshal Petain signed an armistice with the Germans at Compiegne, bringing the invasion of France to an end. Renault’s factory at Billancourt was thus within the zone of occupation of German forces in northern France and squarely under the control of the French Vichy government – the collaborationist puppet government operating in France under German direction. Management of Renault’s factory was administered by the Germans and, whilst undoubtedly he did work under these conditions, it is hard to see what other choice he may have had in the matter.
It is perhaps surprising to many that the functions of government in France still continued during this Vichy period and this patent from M. Renault is a good example of this. Despite the occupation, his patent was granted on 17th February 1941 and published on 16th May that year. Whether or not this patent might even be considered valid is perhaps debatable, given questions over the legitimacy or otherwise of the Vichy government, but it would not matter to M. Renault. The vehicle was never built or deployed, it was too late to have any utility for French forces and, although it is hard to imagine that the German occupiers would not have seen it, they took no action either.
M. Renault died on 24th October 1944, just weeks after his incarceration in the prison at Fresnes, Val-de-Marne, south of Paris, awaiting trial for alleged crimes of collaborating with the Germans. This patent, like many others filed during this Vichy period, were filed and forgotten.
- French Patent FR865243 filed 21st December 1939, granted 17th February 1941, published 16th May 1941
- Vauvallier, F. (2014). French Tanks and Armoured Vehicles 1914-1940. Histoire and Collections, Paris, France