The Gatling gun is one of the best-known early rapid-fire weapons and a forerunner of the modern machine gun. Invented by Richard Gatling, it is known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat. Later it was used in the Boshin War, the Anglo-Zulu War and still later in the assault on San Juan Hill during the Spanish–American War.