In the reign of the Conqueror and his immediate descendants, the rapid building of castles for overawing the defeated Saxons was a matter of Crown policy, but with the settlement of the Kingdom, and the rise into power of Norman nobles waxing rich and powerful upon their estates, restrictions became imperative if the royal prerogatives were not to be set at nought. Consequently, special licences to build and crenellate had to be obtained before erecting, or adding to the existing defences of, a castle, and the rigorous insistence upon this law was readily recognised and maintained by all strong rulers of the kingdom. When, however, a weak monarch came to the throne, or internal dissensions occurred, the Norman barons invariably seized the opportunity thus afforded, and a large increase of these fortalices sprang into existence. The most remarkable example was during the eighteen years of strife wherein King Stephen was struggling for his crown with the forces of Queen Maud. In order to propitiate the nobles and secure their services, the King gave licences with a reckless indifference to consequences, and many scores of castles were erected under these permissions, but a still greater number with no licence at all. These latter became known as "adulterine" or spurious castles; the total number built during this period of anarchy is said to have been more than one thousand, but more modern computation places the number at about seven hundred. Stephen, when too late, perceived the mischief attending the multiplication of these citadels, and attempted to reduce the evil by destroying those belonging to the clergy. The essay proved to be a mistake, and during the disorder that ensued, the land became a prey to anarchy of the most violent kind, each baron or leader of mercenaries doing that which was right in his own eyes, and retreating to the safe precincts of his castle when in difficulties.
Of the nature of these unlicensed strongholds there is considerable doubt, but a great probability exists that they were of very rapid construction and, therefore, not of the Rectangular Keep type, but of the Motte and Bailey, or of the Shell Keep pattern. That a large amount of time had been spent in their erection seems to be negatived by the fact that upon the accession of Henry II. the great majority of "adulterine" castles were destroyed in the course of a few months. This would have been impossible if solid masonry erections were in question, but hastily improvised defences built by forced, and therefore, probably, unskilled labour, would not present great difficulties. In all likelihood a great number of the earthworks which occur in England, and have not been assigned to any particular date, may owe their origin to this disturbed period, especially those of the Motte and Bailey type. Upon the whole, we can hardly look upon the reign of King Stephen as a period distinguished by an advance in the art of castle-building, but rather as one of temporary retrogression to elementary types.
With the advent of the second half of the twelfth century the Castle began to show in many details the influence of the Early English style of architecture, though ornamentation is singularly rare in early castellation compared with the lavish wealth bestowed at the same time upon ecclesiastical buildings. The Norman style was still adhered to in the main outlines, but the external pilasters developed to such an extent that they became buttresses, as at Clun and Dover, the masonry workmanship improved, local stone came more into use, and internal decorations, such as ribs to the vaulting, began to be introduced. It is not uncommon to find the dog-tooth ornament employed in conjunction with contemporary work in the Norman style, but so long as the Rectangular Keep remained, the internal arrangements became, as it were, stereotyped, and were strictly adhered to. The latest styles of Rectangular Keeps carried but few, if any, suggestions of Norman architecture as they trended upon the Early English periods; thus Fonmon Castle in Glamorganshire, and Penhow in Monmouthshire, exhibited no traces of pilaster buttresses, and other features so strongly marked in earlier examples.
Bamborough Castle, grim, grey, and imposing, by its vastness and massive proportions, stands upon a rocky height of igneous formation on the coast of Northumberland. It is by nature a promontory fortress, and as such was seized by Ida and his Angles in 547, and who thence extended his sway over what subsequently became the kingdom of Bernicia. The castle is mentioned in 774, and was twice taken by the Danes. In 1095 the dramatic siege occurred with which Bamborough will be for ever associated. William Rufus besieged it with a formidable army, but such was the reputation of its impregnability that he would not venture upon storming it. He, therefore, had recourse to a siege, and one great beffroi he raised was so formidable that it is mentioned by name, malvoisin; this he advanced to the walls, and so closely that conversation could easily be exchanged between the rival combatants. The rebel baron, de Mowbray, left the Castle in charge of his wife, with the intention of procuring assistance, but was captured in an attempt upon Newcastle. By the King's orders he was brought to Bamborough and exposed to the gaze of the garrison: upon a royal threat to put out the eyes of his captive unless the Castle surrendered at once, the heroic Matilda de l'Aigle, who had continued the defence with the utmost success, admitted the King's forces. De Mowbray was imprisoned, but in his old age was permitted to enter the monastery of St. Alban, where he died.
Rufus appointed Eustace Fitz-John of Alnwick as castellan, and the Castle, in the time of Stephen, successfully resisted an inroad of David, King of Scotland. In 1164 the great Keep was erected by Henry II., and from that period the Constableship of Bamborough became a royal appointment.
