I know that Gatling guns were used during the Civil War and Spanish-American War, but were they ever used during the Indian Wars?
The forerunner to the machine gun, the Gatling gun fired 350 rounds a minute (if it didn’t jam) from a bank of 10 revolving barrels turned by a crank and fed from a hopper. Like the Hotchkiss “Mountain” gun, it could go anywhere a wheeled vehicle went—which meant it was rarely used in timber or rough mountain country.
The military was split on the effectiveness of the Gatling gun during the Indian Wars. George Custer declined taking Gatling guns in to battle at the Little Big Horn in June 1876 because he thought they would hamper his mobility (probably a big mistake on his part). They were used to rake Cheyenne positions in Oklahoma in 1875, killing six. During the Red River War in Texas, they were used against the Cheyenne on August 30, 1874. And Gen. Oliver Howard used Gatling guns in the Nez Perce War of 1877-78.
Although Army leaders debated just how well the guns worked, I have to believe the sheer firepower exhibited by these weapons was bound to have a psychological effect on the Indians.