Gatling Gun By damiendunn5000 Jan 1, 1862 Invented The Gatling gun is invented by Richard J. Gatling during the American Civil War. Jan 1, 1864 First used General Benjamin F. Butler of the Union army first used the gun at the siege Petersburg. Jan 1, 1866 Adopted by U.S. Army The U.S. Army adopted the gun in 1866