The castle was introduced into England by the Normans. As early as 1067, the Anglo-Saxon Chronicle recorded that the Normans 'built castles far and wide throughout the country, and oppressed the wretched people'; and in the following generation Ordericus Vitalis declared that lack of castles to be one of the main reasons why the English - despite their martial qualities - were defeated.
Domesday Book provides the most complete record of those known to have been built by 1086, 48 in all, 45 in Great Domesday; other sources record a further 21 built between 1066 and 1086. Although Domesday records the bulk of known castles, its record is certainly very incomplete. It has been plausibly argued that perhaps 500-600 castles were constructed between the Conquest and the end of the eleventh century. Clearly, therefore, no attempt was made by the Domesday commissioners to record castles systematically, though the majority of those noticed were the major royal castles established in towns, along the south coast, and on the Welsh march. The social and economic implications of castle-building on this scale within such a short time-span have yet to be properly explored by historians.
There has been some debate as to the nature of the castle introduced after the Conquest, specifically whether it was of the motte-and-bailey variety depicted (without its bailey) in the Bayeux Tapestry, or just a simple ring-work, a ditch and earth bank. It has been plausibly argued that in the circumstances of the Conquest, when there was an urgent need to build large numbers of fortifications as quickly and as cheaply as possible, ring-works were the answer. Indeed, it has even been suggested that mottes were unknown in Europe before 1066. Far from being brought into England from Normandy, the motte-and-bailey design was evolved during the early years of the Conquest and then re-exported to Europe.
The jury is still out on this hypothesis, which cannot be proved or disproved in the current state of our archaeological knowledge. It does, however, seem likely that the first castles built after 1066 were simple ring-works. Mottes, with their much great labour demands, could not easily have been afforded during the first two or three years. The famous illustration in the Bayeux Tapestry may, therefore, be an anachronism; the earliest mottes probably post-date 1068. Thereafter, however, the advantage of defence in height ensured that the motte-and-bailey was the predominant type of castle built. Three-quarters or more of all early Norman castles are of this kind.
Ella S. Armitage, Early Norman castles of the British Isles (1912), is still the most thorough treatment of known castles, and Castellarium Anglicanum, edited by D.J. Cathcart King (2 vols., 1983), of all castle sites, of the Conquest. G. Harfield, 'A hand-list of castles recorded in Domesday Book', English Historical Review, vol. 106 (1991), pages 371-92, provides the most recent treatment of Domesday castles; Richard Eales, 'Royal power and castles in Norman England', Ideals and practice of medieval knighthood 3 (1990), pages 49-78, of the scale of castle-building; and Barbara English, 'Towns, mottes and ring-works of the Conquest', in The medieval military revolution: state, society and military change in medieval and early modern Europe, edited by Andrew Ayton and J.L. Price (London, 1995), pages 45-62, of the Conquest and the development of the motte-and-bailey castle. For calculations as to the labour-costs of different castle forms, see N.J.G. Pounds, The medieval castle in England and Wales: a social and political history (1990).