The bishops appointed "chatelains," one of whom was the celebrated "Wild Boar of the Ardennes," William de la Marck.
Bouillon remained French till 1814, and Vauban called it "the key of the Ardennes."
The surface of the department consists of undulating and well-wooded plains, intersected by numerous valleys, and diversified in the north-east by hilly ground which forms a part of the mountain system of the Ardennes.
Of the former the remnants are now seen in Brittany and the Ardennes; of the latter the Cvennes and the Montagne Noire are the last traces visible on the surface.
The earlier deposits of that sea now rise to the surface in Brittany, the Ardennes, the Montagne Noire and the Cvennes, and in all these regions they arc intensely folded.