 From the middle of the 19th century until the post-war era, the mining and export of coal was a dominant industry.At its peak of production in 1913, nearly 233,000 men and women were employed in the south Wales coalfield, mining 56 million tons of coal.Cardiff was once the largest coal-exporting port in the world and, for a few years before the First World War, handled a greater tonnage of cargo than either London or Liverpool.