“Leibniz vividly described a mobile fortress, a weapon of unimaginable power and destruction that could single-handedly sow havoc among enemy forces.”

By Lloyd Strickland

WITH WARFARE in the 17th century dominated by sieges, cannons, artillery and muskets, the introduction of something akin to an armoured tank would have been a game-changer. Such was the thinking of the polymath Gottfried Wilhelm Leibniz (1646–1716).

Best known as inventor of the calculus and binary arithmetic and renowned in his own day and ours as a mathematician and philosopher, Leibniz was a universal genius who made innovative contributions to numerous disciplines, including the art of war.

He wrote hundreds of manuscript pages on military matters, such as fortifications, artillery, and troop manoeuvres, as well as one in which he devised bulletproof clothing made from silk. However, he published none of his military writings, and most of them remain unpublished even today.

In one these still-unpublished manuscripts, Leibniz vividly described a mobile fortress, a weapon of unimaginable power and destruction that could single-handedly sow havoc among enemy forces. Leibniz called this his “fire cart” and described it as an “iron elephant” with a flat front, a sloping roof and spikes.

The fire cart was a massive contraption capable of carrying up to 20 armoured soldiers. Constructed to withstand a barrage of musket and even cannon fire, this iron behemoth could take on battalions of soldiers all by itself. The idea was that the cart would hurtle across the battlefield with terrifying velocity, smashing everything in its path while the soldiers inside threw grenades at the fleeing enemy.

Although Leibniz did consider the cart being moved by horses placed inside, his preferred method of propulsion was much more novel: gunpowder.  The idea was to use the recoil from exploding charges to drive the vehicle forward. He probably borrowed the idea from his mentor Christian Huygens (1629–1695), who had invented a gunpowder engine in 1680.

Leibniz’s vision did not stop at mere brute force and intimidation; the practical considerations of manoeuvrability and survivability were also taken into account. He suggested the fire cart carry planks to enable it to cross ditches. Its sloping roof would ensure any projectiles thrown its way would harmlessly roll off. Leibniz envisaged only one countermeasure that could impede his rolling fortress: The cart would be vulnerable to any landmines it happened to encounter in its path.

There are virtually no similarities between Leibniz’s fire cart and Leonardo da Vinci’s 15^th century sketch of a fighting vehicle, or da Vinci tank, widely regarded as the earliest concept of armoured warfare as we know it today.

Da Vinci depicted a circular vehicle with a domed roof and 32 cannons poking out through holes around the perimeter. Inside were two large hand-cranks attached to a system of gears; by pushing the cranks, the crew could in theory make the vehicle move in any direction they wanted.

Like da Vinci’s vehicle, Leibniz’s fire cart was never constructed. He was no engineer and would not have been able to make the cart himself. Nor, apparently, did he show his proposal to anyone who could have attempted to build it or have commissioned others to do so.

Even if he had, the technological limitations of the day would have proved an insuperable barrier, and it’s unlikely that gunpowder would have been a powerful enough fuel in any case.

Nevertheless, Leibniz’s fire cart is a testament to his innovative spirit and daring imagination.

An English translation of Leibniz’s manuscript on the fire cart is given below.

Translation of manuscript LH 36 Bl. 226–227 held by Gottfried Wilhelm Leibniz Bibliothek – Niedersächsische Landesbibliothek, Hannover:

The most violent thing I know for routing the enemy would be my fire cart, propelled by gunpowder. It could be capable of holding twenty or so armoured men. It would be strong enough to easily withstand not only musket fire, but something stronger, and if necessary cannon fire, as it can recoil from the impact and be anchored. The men inside would steer it, and throw grenades among the enemies. The cart would overturn and smash everything and cause wounds with its spikes. [Even two carts could go together, having a soft chain from one to the other armed with spikes, and this chain would overturn an entire battalion, but the difficulty would be to make them go together.] It would start running only by small cups of gunpowder, which would make the wheels turn, and the cart, gaining ever more speed, would soon go with terrible violence. It would require wheels all in one piece, and perhaps the greatest part made of iron, or else it would be necessary to keep spares to replace the broken ones. Such a cart would hold sway through a large army, for once it was lined up and going straight, it would go through an entire line of battalions. 

It would be, so to speak, a sort of iron elephant, steered by an overseer, smashing everything, and belching out fire and flames. And in this way, twenty men could put ten thousand into confusion in the open country. Which seems incredible.

If this cart encountered a ditch or something it could not cross or break through, those who steer it would have to turn it around for fear of getting stuck or hindered. They could have planks on hand for crossing ditches, if necessary. The men inside, managing their gunpowder properly, after having undertaken a terrible operation, could still escape from the melee and bring the cart with its people to a place of safety.

It seems foolish to think of something like this, but I don’t see anything that could prevent its success.

Without gunpowder, twenty horses concealed in the cart would also make a rather terrible operation.

There would be a grille of iron bars through which one could see and through which a musket ball would not pass. The cart would have a sloping roof, so that the fireworks would roll down behind the cart by AB, whose front is AC. Instead of the grille there could be very strong iron plates, pierced in several places.

One could even combine horses and gunpowder, but it is necessary to have horses that are not startled by the shots.

As I conceive it, as little powder as possible would be used, since the force it exerts both forward and backward would be sufficient to achieve the same effect. It could be tried with a small suspended cannon, to see how much strain it puts on the side.

When the cart is going fast, it would be difficult to throw bombs into it; they could even be made to bounce off or be thrown back. But it could be countered by small mines or fougades, which it would set off when passing over them.

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Lloyd Strickland is a professor of history, politics and philosophy at Manchester Metropolitan University. You can follow him at @Dr_L_Strickland