In 1859, the Clinton and Soho iron furnaces introduced coke-fire smelting to the region. The American Civil War boosted the city's economy with increased production of iron and armaments, especially at the Allegheny Arsenal and the Fort Pitt Foundry. Arms manufacture included iron-clad warships and the world's first 21" gun. By war's end, over one-half of the steel and more than one-third of all U.S. glass was produced in Pittsburgh. A milestone in steel production was achieved in 1875, when the Edgar Thomson Works in Braddock began to make steel rail using the new Bessemer process.