Post-Roman and English Earthworks. 31
was of a very fluctuating description, and the Welshmen must not only have been perfectly familiar with the English method of construction, but from time to time have been actually in possession of their strongholds. That the Welsh used timber for defensive purposes appears from their law by which the vassals were to attend at the lord's castle for its repairs or for rebuilding, each with his axe in his hand. In some cases in these Border works there is scarcely any mound, at others the mound is low and hollow in the centre. Caer Aeron and another small earthwork near Builth seem to have been the earthen bases of a mere circular wigwam. Caer Aeron cannot have been a mere temporary structure, as the circumscribing ditch has been cut with considerable labour in the rock. It is very evident, both from the existence of Offa's dyke, and from the immense number of these moated mounds thrown up along its course, that the English had early and long possession of large tracts of the border territory. Offa ruled over Mercia from A.D. 757 to 796, and his dyke extends from the mouth of the Wye to that of the Dee. At its northern part, for about forty miles, is a second work, known as Wat's Dyke, a little in its rear, and thought to be a somewhat earlier work, also by Offa. Before the actual line of a work so galling to the spirit of a turbulent people could have been decided upon there must have been many years of contest along the border, and the English must have had something like permanent possession of the land on either side, and have held estates of which the mounds still existing were the "capita" or chief seats. The dyke, it should be remembered, was rather a civil boundary than a military defence.
It is further to be remarked that moated mounds corresponding precisely in pattern to those in England, are very numerous in Normandy. In size they vary within much the same limits. All have or had a proper ditch, some, as Briquessart and Des Olivets, stand in the centre of the court, some at one end, others on the edge. The court is sometimes circular, most commonly oblong, very rarely indeed rectangular. The outer enclosures have their ditches, which communicate with those of the inner defences. M. de Caumont gives a list of fifty-four of these mounds, within a radius of sixty miles from Caen, and since he wrote many more have been observed. These also were, from an early period, the seats of great landowners, and from very many of them came the knights and barons who accompanied William to England, and there settled in posts very similar. Sir F. Palgrave gives a list of 131 of these fortified residences in the Cotentin, the Avranchin, and the Bessin, which includes
