3. Gatling Gun
Invented by Richard Jordan Gatling in 1861, the Gatling Gun was the first widely used machine gun, offering rapid firepower during the Civil War. Its rotating barrels and unprecedented rate of fire heralded the arrival of automatic weaponry in U.S. conflicts. Despite its potential, it saw limited use during the Civil War but paved the way for future advancements in military technology. (history.com)
