Amboise10 The Tank This tank was designed to penetrate enemy lines and sow panic thanks to its cannons. The idea was not completely new because the German engineer Konrad Keyser had already imagined a self-propelled armored vehicle in the fifteenth century. Eight men turning the cranks through a set of gears can drive this armed "tortoise". Although the weight of the cannons and armor of the carapace made the functioning of this model improbable, it is known today that a friend of Leonardo da Vinci, the military leader Del Monte, used tanks in battles. So the Russians using sloped armor for their T-34 tanks in WWII was not an entirely new invention.