The symbol of the authority of the military class, the outward and visible sign of feudalism, was the castle, where the lord resided and from which he exercised his authority over his fief. Originating in the period of anarchy which accompanied the dissolution of the Frankish empire and the invasions of the ninth and tenth centuries, the castle spread over northern France as feudalism spread, and was introduced into England by the Normans when they here established their feudal state. The earliest castles of Normandy and of England were not, however, the massive stone donjons which Freeman peopled with devils and evil men. With some exceptions, of which the Tower of London is the most noteworthy, these ‘hateful structures’ were built of wood and surrounded by a stockade, surmounting an artificial mound, or _motte_, thrown up from the deep moat at its base. A great drawbridge, cleated so that horses should not slip on the steep incline, led from the farther side of the moat directly to the second story of the tower, of which the ground floor, used only for stores and the custody of prisoners, had no entrance from without. Fortresses of this type have naturally left nothing behind them save the outlines of their mounds and moats, but they are well known from contemporary descriptions and are clearly discernible in the Bayeux Tapestry, which gives rude pictures of the strongholds of Dol, Rennes, Dinan, and Bayeux, and shows a stockaded mound in actual process of construction at Hastings. The heavy timbers of these lofty block-houses offered stout resistance to battering rams, but they were always in great danger from fire, and wood was replaced by stone in the course of the twelfth century, to which belong the ‘stern square towers’ which still survive in Normandy and England, as well as the earliest examples of the more defensible round keeps and square keeps flanked with round towers. Whether of wood or stone, the donjon was a stern place, built for strength rather than for comfort, and bending the life of those within it to the imperious necessities of defence. Space was at a premium, windows were few and small,--sometimes only a single window and a single room to each story,--trap-doors and ladders often did the work of stairways, and from the wooden castles fires were usually excluded. Nevertheless the donjons were not, as was once supposed, mere “towers of refuge used only in time of war,” but “were the permanent residences of the nobles of the eleventh and twelfth centuries.”[49] Only toward the close of this period do the outer buildings develop, so as to give something of the room and convenience demanded by the rising standard of comfort; only in the thirteenth century do the more spacious castles without keeps begin to make their appearance.