The military rôle of the castle is the most obvious, the most romantic, and basically the most important. Though the castle was always a residence no less than a fortress, and though from these two fundamental rôles others subsidiary followed, it was military necessity which first called the castle into being, whether at the time of its origin in ninth- or tenth-century France or whether in the England of the Norman Conquest, and military necessity which caused precisely that fusion of the lordly residence and the stronghold which is the peculiar characteristic of the castle. It is, after all, the degree of fortification which distinguishes a castle from a house. Warfare in the earlier centuries at least turned first and foremost upon the castle, and though from the later fourteenth century the military importance of the castle may have begun to decline, to read of wars in the chronicles of the eleventh, twelfth and thirteenth centuries is largely to read of sieges, while the surviving records of English royal government, for example, show beyond doubt that the maintenance of castles and their fortification and preparation for war were primary concerns of contemporary military organization. If we begin to ask why this was so, one fundamental answer – by no means widely understood since medieval warfare is a widely neglected subject – is that the military rôle of the castle was not just defensive but also offensive. Indeed we may argue that the latter is primary, for it was the offensive capacity of the castle, its function as a base, heavily defended, for active operations by means of which the surrounding countryside could be controlled, that gave it much of its value in war, made it the prized object of attack, and thus accounts for all those sieges. Only in this way, therefore, is the defensive role of the castle its most characteristic, though certainly it is the sieges which attracted the limelight of recorded events. Because the base and residence should be as impregnable as possible, it is defence also which, above all other considerations and requirements, dictated the castle's design and architectural form in the centuries of its supremacy in war, even though it had to fulfil as well its other functions as lordly and prestigious dwelling, centre of local government and administration, and, it might be, treasury, armoury or prison.