Early iron smelting used charcoal as both the heat source and the reducing agent. By the 18th century, the availability of wood for making charcoal was limiting the expansion of iron production, so that England became increasingly dependent for a considerable part of the iron required by its industry, on Sweden (from the mid-17th century) and then from about 1725 also on Russia.
Smelting with coal (or its derivative coke) was a long sought objective. The production of pig iron with coke was probably achieved by Dud Dudley around 1619, and with a mixed fuel made from coal and wood again in the 1670s. However this was probably only a technological rather than a commercial success. Shadrach Fox may have smelted iron with coke at Coalbrookdale in Shropshire in the 1690s, but only to make cannonballs and other cast iron products such as shells. However, in the peace after the Nine Years War, there was no demand for these.