Then the forest south of Brussels was crossed by the river Senne/Zenne and extended as far as Hainaut, covering most of the high ground between the Senne and the Dyle/Dijl.

[3] In the Middle Ages, the forest extended over the southern part of Brabant up to the walls of Brussels and is mentioned, under the name of Ardennes, in Byron's Childe Harold.

A major blow towards this 19th-century contraction was struck when Napoleon ordered 22,000 oaks to be cut down to build the Boulogne flotilla intended for the invasion of England.

[7] The forest served for a long period as an exclusive hunting ground for the nobility, but today is open to the general public.

Due to human influence (encroachment from all sides of the outer edges as well as the long-established thoroughfare roads and highways cutting deep through the forest) and impoverishment of the ecosystem, various plants and animals have become extinct.

Of these, seven have disappeared altogether: the brown bear (around 1000), the wolf (around 1810), the hazel dormouse (around 1842), the red deer, the badger and the hare.

Other animal species found in the forest, including the black woodpecker and the great crested newt, are considered endangered and are protected by the European Habitats Directive.

Various types of wildlife crossings have been or are due to be constructed to reconnect the areas of the forest that are currently divided by large roads.

[15] Amongst the contemplative monks and nuns who lived and prayed in the forest, the most notable was John of Ruysbroeck who established a Monastery near Groenendaal at Vauvert.

From Roman times, it had generally been seen as a tactical blunder to position troops for battle in front of woodland because it hampers their ability to retreat.