The multi-barrelled machine gun was a weapon with remarkable firepower. Da Vinci sketched this rolling artillery battery around 1480 while in Florence, perhaps as a calling card to a warrior prince in need of a military architect. A hand crank adjusts elevation, and reloading is a major challenge – especially when under fire .
Though capable of rapid-fire which later model machine guns became noted for, this his housed an ingenious aiming and loading mechanism. By widening the field of fire, the fan-like shape of Da Vinci’s prototype made it a potentially effective weapon against a line of advancing troops. In addition Da Vinci’s design was easy to move around on the battlefield because it was lightweight and mounted on wheels