These and similar works evidently belong to the earlier period of the northern invasions, when the long black galleys of the vikings visited at not infrequent intervals the British and Irish shores, before they settled in either land. In the fifth and sixth centuries settlements began to be formed in Britain, and speedily assumed dimensions very formidable to the natives. The south-eastern coast of Britain, infested even in Roman times by the sea-rovers, and thence known as the Saxon shore, had been fortified by the Romans, but the works, intrinsically strong, were too weak in British hands to stem the progress of the foe. In A.D. 530, Cerdic and Cynric took the Isle of Wight, and slew many Britons at a place where Wightgar was afterwards buried, and where he probably threw up the work which bore his name, and afterwards, as now, was known as Carisbroke. In 547, Ida, the “flame-bearer” of the Welsh bards, founded Bebbanburgh, now Bamborough, and enclosed it first by a hedge [hegge], and afterwards by a wall; and in 552 Cynric engaged the Britons at Sorbiodunum, afterwards Searo-burh, and now Old Sarum; as did in 571 Cuthwulf or Cutha at Bedcanford or Bedford, in each of these two latter places, as at Carisbroke and probably at Twynham or Christchurch, throwing up the works which yet remain. The conquest of the Romano-British cities of Cirencester, Bath, and Gloucester, and the whole left bank of the Severn, from the Avon of Bristol to that of Worcester, was the immediate consequence of the victory of Deorham in 571, and was followed by the possession of Pengwern, afterwards Shrewsbury, a most important post, and one by means of which the Mercians, and after them the Normans, held the Middle March of Wales. All along the line from Christchurch and Carisbroke, by Berkeley and Gloucester, Worcester, Warwick and Shrewsbury, earthworks were then thrown up, most of which are still to be seen.