Coal was the fuel of the industrial revolution; the black gold which powered the British Empire. The energy rich mineral remains of organic matter many millions of years old, coal replaced wood as the staple resource of the Industrial Revolution. The advances in engineering seen in that time simply would not have been possible without coal.
Coal has been found to have been used in prehistoric and Roman times for things including funeral pyres, drying grain and small-scale heating. Mining on a larger scale than simply surface scrape-off began in the medieval period, with small shafts or 'adits'. By the 15th century, mines existed across Wales, mostly for use in small-scale industry. During the 16th and 17th centuries, an export industry developed, mostly around Swansea, Pembrokeshire and Flintshire. Production began to accelerate.
It was during the 18th century that the Industrial Revolution really got going and the Welsh coal fields were well placed to benefit. Charcoal gave way to coal as the fuel of choice for smelting, and with machinery becoming available, production could continue to meet demand.