Leonardo's fighting vehicle

I will make protected wagons, reliable and impregnable, which, piercing the enemy's ranks with the fire of their artillery, will destroy him, no matter how great the number of his soldiers.

[2] Sometimes described as a prototype of modern tanks, Leonardo's armored vehicle represented a conical cover inspired by a turtle's shell.

Slanting angles would deflect enemy fire, similar to sloped armour today.

to have been a deliberate mistake by Leonardo as a form of security, in case his design was stolen and used irresponsibly as seen in his other designs where he also used mirror writing, it is almost impossible to fix this problem successfully without taking away power from its forward movement and strength.

However in the documentary "Da Vinci's Machines" (2009), a team of engineers and craftsmen undertook the challenge of reconstructing Leonardo da Vinci's design for an armored vehicle, commonly referred to as his tank, the successful operation and movement of the tank by fixing the purposely placed design flaw with the gearing not only validated da Vinci's innovative thinking but also showcased the capabilities of contemporary engineering to reinterpret historical designs, although it would have lacked the battlefield mobility seen in modern tanks that make them so effective today.