The plain of the Upper Severn, open and fertile, outside the Shropshire border, was contested from a very remote period between the Mercians and the Welsh, and was at times completely and permanently occupied by the former. The Mercian fortresses of this very perilous district were moated mounds similar to those thrown up in England in the ninth and tenth centuries. Of these there are very many along the course of the river or in its tributary valleys, of which the chief are Keri, Hên-domen near Montgomery, Nantcribba a fortified natural knoll, Guilsfield, a burh at Chirbury thrown up by Æthelflæda and now removed, Welsh Pool designated in 1299 as Mota de Pola, a mound on the Luggy, Winsbury, Dudston, Brynderwen, several mounds about Llanidloes and Moat-lane, Tafolwern, a fine mound upon the junction of two streams with the Afon Lwymyn, and whence some of the charters of the Welsh Princes are dated, and a remarkable mound at Talybont near Towyn, whence Llewelyn dated a letter to the Archbishop of Canterbury, and which was visited by Edward I. Very few of these “Mottes” were surmounted by works in masonry, and the accompanying extract from the Close Roll shows that even as late as the reign of Henry III. timber was the recognised material for their defences:— “Rex etc dilecto et fideli suo Godescallo de Maghelins salutem. Recipimus tibi quod ex parte nostra firmiter precipias omnibus illis qui motas habent in valle de Muntgumery quod sine dilatione motas suas bonis bretaschiis firmari faciant ad securitatem et defensionem suam et parcium illarum. Teste Rege apud Weston xxx die maii, 9 H iii, 1225.” (Close Roll.) The Brut y Tysogion says that the castles of Llandwnyl, Trevuverw, and Cynfig were begun in 1092 to be built stronger than before; for before that time castles were of wood, and before long the Frenchmen had built their castles over the whole country. Although it is evident that the moated mound was an English and not a Welsh fortification, yet many of these mounds are found in situations where no English household could have lived, and others, like Tafolwern and Talybont, are known to have been Welsh residences, so that it would seem that the Welsh, finding this form of fortification both simple and strong, easily thrown up, and when burned easy to repair, had recourse to it in imitation of their foes. Almost all the castles in Shropshire on the border were held of Earl Roger, or some Lord Marcher by the tenure of castle guard, and many of the lesser castles had lands attached to them held by the same honourable service. The usual condition was attendance upon the lord in time of war, armed, for a period of forty days, or an engagement to defend and sometimes to repair a particular part of the lord’s castle. Lord Coke indeed speaks of tenure by castle guard as always attached to some specific part of a castle. The manor of Hodnet was held by the service of seneschal, and in war by attendance in the outer bailey of Shrewsbury Castle.