Imagine a triangular saucer of rough woodland with the River Severn on the right hand side and the River Wye as the boundary on the left. Imagine, further, that the saucer has been nipped by geological pressure as England slowly grinds up against the bedrock of Wales causing North-South crumpled creases in the rocky structure of the bowl - a bit like a paper fan. That is the land on which what is now the Forest of Dean stands.
In the past the woodland and waste land that filled that triangle was mainly uninhabited ... a few isolated manors that slowly decayed and were abandoned as the rocky soil was not very good for agriculture and some small hamlets and villages that surrounded the main core of woodland.
Beneath the crumpled and steeply wooded hillsides there were industrial treasures - iron, coal, lead, a smidgeon of gold and lots of stone whilst on the surface itself broadleaved trees grew tall as they struggled for the sunlight from the steep and darkly shadowed valleys. Primitive man gathered up the surface or near-surface iron ore wherever it was reachable, later the Romans came and delved for lead a bit more efficiently and, later still, medieval man learned to use the timber as fuel for very primitive but effective Bloomeries (iron foundries using charcoal as the fuel) forging the iron that local men, women and children won from underground.
Later still timber, in the form of charcoal, was superceded by the local coal as the fuel for the iron foundries and timber became a most important 'crop' in its own right - oak for the production of ships for the Royal Navy. So grew up, over time, a set of industries based on iron (and later steel), coal, timber and stone.
In the middle of these gradual changes in the technologies and development of local industries a significant 'step change' occurred ... King William I (William the Conqueror) landed in England with his armoured knights on heavy horses with supporting archers - fought and beat the local English and stayed as the new monarch. After identifying the contents of every part of the country (in the Domesday Book) he organised the clearance of all those old manors and took the major part of that triangle of land that was not 'owned' as common land by any existing village and declared it to be a hunting area for the exclusive use of him and his guests.
Thus was the Forest of Dean born - taking its name from an already existing manor 'Dean' in the North-East of the area. The history of the Forest reflects a pendulum struggle between twin interests, sporting and timber (the King) and industrial (local people and the Church) - with an interesting 'see-saw' between the two as, on the one hand, the needs of industry ate into the timber - both as a raw material and as a fuel and then the need for timber - required by the Royal Navy, on the other hand, pushing back its' industrial use. When coal supplanted timber as the fuel then timber was needed to support the tunnels and shafts for a time despite the need to use it for building the King's ships. Of course, with the advent of the iron-clad steamer the need for timber as a ship-building material diminished whilst the need for coal to power ships rose.