The Maxim Gun was the first fully automatic machine gun in the world, invented by Hiram Stevens Maxim in 1884. It used the recoil energy of the fired bullet to reload and fire the next one, making it a self-powered weapon that could fire up to 500 rounds per minute. The Maxim Gun was adopted by the British Army in 1887 and was used in various colonial wars and conflicts, such as the Mahdist War, the First and Second Boer Wars, and the Boxer Rebellion. It was produced in nearly every contemporary rifle calibre according to national needs, though very first ones manufactured were chambered in .577/450 Martini-Henry, the same cartridge as the contemporary Martini-Henry Rifle. The Maxim Gun was an enormously powerful and influential weapon that changed the nature of warfare and is considered the predecessor of all modern machineguns.