For purposes of defence Britain had been divided into two provinces--the north, commanded by a Dux Britannorum, or, as he was called in Welsh, the _Gwledig_; and the south-east, commanded by the Count of the Saxon Shore. Of these the first is the more important in Welsh history. The most famous holder of the office was Cunedda. His seat of {36} government originally was in the north; but being compelled to give way to the Picts, he led his Brythons into Wales, where he established himself at Deganwy on the Irish Sea. One of the greatest of Cunedda's descendants was Maelgwn Gwynedd. He perceived that if Wales remained composed of a number of petty independent principalities no other fate could possibly await it than to be swallowed up piecemeal by the foreigners. Accordingly, partly by argument and partly by artifice, he persuaded the other chieftains to acknowledge him as the heir to Roman power, and to bow to his overlord ship. This was about the year A.D. 550. Nevertheless the Saxon advance continued. Under their leader Ceawlin they marched up the Severn valley; and, in the year 577, won a great victory at Deorham, the result of which was that they reached the Bristol Channel, thus cutting off the inhabitants of Devon and Cornwall for ever from their kindred in Wales. Some little time later Ethelfrith, king of the Angles, marched against Chester, won a battle there in 613, and established his power as far as the Irish Sea. This meant that a wedge was driven in between the people of Wales and the Welsh people of Strathclyde. Meanwhile all along the border {37} English power was being consolidated under the able and vigorous kings of Mercia; and soon Offa's Dyke was raised to mark the boundary. Thus by the middle of the seventh century Wales had assumed what were to remain to all intents and purposes ever afterwards its geographical limits. Internally the country was forming itself into the principal territorial divisions which remained until superseded by the shire system of Edward I. The extreme north was called Gwynedd. Next came Powys, roughly corresponding to our Montgomeryshire. Modern Cardiganshire was called Ceredigion. Corresponding to Pembrokeshire was Dyfed. Carmarthen represents the ancient Deheubarth, and Glamorgan the ancient Morganwg; while between the Usk and the Wye was the principality of Gwent.