What military device did Leonardo da Vinci design with 33 separate gun barrels?

Leonardo da Vinci designed a 33-barrel organ, a multi-barrel gun intended for military use.

The design placed 33 small cannons in three rows on a wheeled frame. The arrangement allowed one row to be fired while the other rows cooled or were reloaded. Because the gun barrels resembled the pipes of a musical organ, the weapon acquired the name organ gun.

Leonardo’s version was meant to increase the rate of fire compared with a single cannon. The frame could be tilted and repositioned, and the many barrels could produce a concentrated volley against troops. It was still a black-powder weapon, so it lacked the rapid, self-loading operation associated with modern machine guns.

The 33-barrel organ is sometimes called a machine gun in popular accounts, but that label can mislead. Leonardo’s weapon fired separate cannon charges and required manual loading. It remained a proposed Renaissance military machine rather than a documented battlefield success.