The Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. Its first combat usage, and the battlefield role it is most well-known for, was its use by the Union forces during the American Civil War in the 1860s. Later it was also famously used in the assault on San Juan Hill during the Spanish-American War.[1]
Developed following the 1851 invention of the mitrailleuse by the Belgian Army, the Gatling gun was originally designed by the American inventor Dr. Richard J. Gatling in 1861 and patented in 1862.[2] He wrote that he created it to reduce the size of armies and so reduce the number of deaths by combat and disease.[3]
Although the first Gatling gun was capable of firing continuously, it required a person to crank it; therefore it was not a true automatic weapon. The Maxim gun, invented in 1884, was the first true fully automatic weapon, making use of the fired projectile's recoil force to reload the weapon. Nonetheless, the Gatling gun represented a huge leap in firearm technology. Prior to the Gatling gun, the only rapid-fire firearms available to militaries were mass-firing volley weapons as the mitrailleuse or grapeshot (as fired from cannons, similar to shotguns). And though rate of fire was increased by firing multiple projectiles simultaneously, these weapons still needed to be reloaded after each discharge, which for multi-barrel systems like the mitrailleuse was quite cumbersome and extremely time-consuming, thus negating their high rate of fire per discharge and making them impractical for use on the battlefield. In comparison, the Gatling gun offered a rapid continuous rate of fire without needing to manually reload.
The gun's operation centered around a cyclic multi-barrel design which facilitated cooling and synchronized the firing/reloading sequence. Each barrel fired a single shot when it reached a certain point in the cycle, after which it ejected the spent cartridge, loaded a new round, and in the process, cooled down somewhat. This configuration allowed higher rates of fire to be achieved without the barrel overheating. Some time later, Gatling-type weapons were invented that diverted a fraction of the gas pressure from the chamber to turn the barrels. Later still, electric motors supplied external power to operate the Gatling gun.
