Beginning in 1794, Eisenschmitt lay under French rule. In 1814 it was assigned to the Kingdom of Prussia at the Congress of Vienna. In 1835, Eisenschmitt had roughly 1,350 inhabitants, the highest population figure in its history. As the 19th century wore on, however, an end was brought to the iron industry in the Salm valley by new production processes and more productive as well as bigger ironworks in the industrial areas on the Lower Rhine and the Ruhr, which moreover could be worked with the more economical coal instead of with charcoal.