Forges in the Bertranges forest
The Nièvre department was one of the main region for producing metal before being supplanted by Lorraine and Northern France steel-producing areas in the 19th century. The disappearance of the Nivernais forges can be explained by the replacement of wood charcoal by coal whose calorific value is much higher. Nivernais forges history is closely linked to the trilogy “water + wood + ore”. It’s why forges are located in forests to reduce transports.
The Bertranges forest underground contains, not far below the surface, ferruginous pisolites which are very good iron ore to produce steel.
On the eve of the French revolution, Nièvre department has about a hundred steel mills sites of which about 40 were located in and around the Bertranges forest (present-day canton of La Charité-sur-Loire): Beaumont-la-Ferrière (1 furnace and 11 forges), Chasnay (1 furnace and 4 forges), Murlin (5 forges), Nannay (1 furnace and 1 forge), Narcy (1 forge), Raveau (2 furnaces and 7 forges), Saint-Aubin-les-Forges (9 forges) et Varennes-lès-Narcy (1 forge). According to Georges Dufaud, on the 11500 tonnes of cast produced in 1826 by the twenty-some furnaces of the Nièvre department, 10% were melted by those of Cramain (Chasnay) and Raveau.
In the Annales des Pays Nivernais (1982), Stainmesse estimates that a forge needs 15 hectares of coppices per year to operate and a furnace with a forge integrated 100 hectares per year. If one looks the hundred steel mills sites already mentioned, the annual wood consumption is considerable.
The effects of the decline, and its disappearance at the beginning of the 20th century, of the Nivernais forges had very important impacts on the forest regeneration. In that respect, for more than 150 years, the conversion of coppice forest into high forest has resulted in the creation of one of the most beautiful oak-tree forest in Europe whose trees are much sought after by coopers for their fine grain.
Photo : Extract from the Cassini map (1756-1758) : forges and furnaces are located on the rivers to use water as driving force.