Leonardo da Vinci designed an organ gun by arranging many gun barrels in parallel.
The weapon, also called a ribauldequin or multiple-barrel gun, was intended to fire a volley of projectiles. Leonardo’s version used a frame holding numerous small barrels, producing an appearance similar to the pipes of a musical organ. The arrangement could increase the number of shots delivered against a formation of troops.
The design was part of Leonardo’s military engineering work in the late 15th century. It was a concept for battlefield use, not a modern machine gun: the barrels still required separate loading and ignition, so sustained automatic fire was impossible.
The term “organ gun” refers to the visual arrangement of the barrels rather than to musical operation. Similar multiple-barrel weapons existed before and after Leonardo, so he should not be credited with inventing every form of the weapon. His drawings are notable for adapting the idea into a carefully organized military machine.