Of the nature of the houses within the bailey, little can be said. They doubtless included shelters for the garrison of the castle, stables for their horses, and various sheds or store-houses. The hall, or building, which was the centre of the domestic life of the castle, was, from the earliest times, the chief building within the circumference of the bailey. We read of the destruction of the _principalis aula_ of the castle of Brionne in 1090, by the red-hot darts which were hurled upon its shingled roof;[62] and stone halls, as at Chepstow and Richmond, were built before the beginning of the twelfth century. But it is certain, on the other hand, that the donjon was, now and later, adapted to domestic as well as purely military uses; and it seems likely that the owner of the castle, in certain cases, was content with his dwelling upon the mount, until, at a later date, the strengthening of the whole enclosure with a stone curtain made it possible for him to raise a more convenient dwelling house within the more ample space of the bailey. In the larger castles, however, where there was a strong permanent garrison, a hall was a necessity for their entertainment. Where mount-and-bailey castles are found without a trace of stonework, it does not follow that they are necessarily of a date immediately subsequent to the Conquest. Many of these castles, founded by the Conqueror and his followers, became permanent strongholds, and in due course of time were fortified with stone walls and towers. Others were probably founded as an immediate consequence of the Conquest, and were abandoned in favour of other sites. Thus it has been thought that the earthworks at Barwick-in-Elmet, near Leeds, were abandoned by Ilbert de Lacy, when he fixed upon Pontefract as the head of his honour.[63] Trecastle may have been deserted by Bernard of Newmarch for Brecon, or it may have been held by a small garrison as the western outpost of his barony. But it is well known that, for a long time after the Conquest, in the period of constant strife between the Norman kings and their barons, a large number of castles came into existence in defiance of royal edicts. We know that, during the reign of Stephen, when every man did what was right in his own eyes, an almost incredible number of unlicensed or “adulterine”[64] castles were constructed. As a result of the agreement between Stephen and Henry II., many of these were destroyed, and the number of English castles was materially lessened. Later on, when the revolt of the Mowbrays against Henry II. took place, the victory of the king’s party was followed by the destruction of the Mowbray castles at Thirsk, Kirkby Malzeard, and Kinnard’s Ferry in the isle of Axholme, and of Bishop Pudsey’s castle at Northallerton. Of these four castles earthworks or traces of earthworks, but no stonework, remain. It is reasonable to suppose that the material of their fortifications was timber. Haste in the construction of castles,