Billinghurst-Requa battery

Although the Gatling gun, patented on 4 November 1862, would prove a superior weapon, the Billinghurst-Requa battery, an advanced organ gun patented on 16 September 1862, predates it and is widely regarded as the first "practical" machine gun to be used during the American Civil War. It was the invention of the self-contained metal cartridge that made the organ gun (also known as the volley gun) a practical weapon. The cleverly arranged breech, which closed on a piano hinge, allowed for the ammunition strips to be loaded, fired, extracted, and reloaded quickly by the crew of three.