The coal industry in Wales has played an important role in the Industrial Revolution in Wales. Coal mining expanded in the eighteenth century to provide fuel for the blast furnaces of the iron and copper industries that were expanding in southern Wales. The industry had reached large proportions by the end of that century, and then further expanded to supply steam-coal for the steam vessels that were beginning to trade around the world. The Cardiff Coal Exchange set the world price for steam-coal and Cardiff became a major coal-exporting port. The South Wales Coalfield was at its peak in 1913 and was one of the largest coalfields in the world. It remained the largest coalfield in Britain until 1925. The supply of coal dwindled, and pits closed in spite of a UK-wide strike against closures.