Leonardo's armored tank remains one of the most impressive of Leonardo's designs. The armored vehicle was designed to be capable of moving in any direction bristling with cannons on all sides. One soldier sat in the turret to give directions. To move it, eight men inside the tank turned cranks attached to trundle wheels which were in turn attached to the four large wheels. This design planted the seed for future engineers to isolate initial problems and come up with design solutions. The concept of an armored tank came into fruition in World War I.