England–Wales border point. In 926, Edward's successor Athelstan, "King of the English", summoned the Welsh kings including Hywel Dda of Deheubarth to a meeting at Hereford, and according to William of Malmesbury laid down the boundary between England and Wales, particularly the disputed southern stretch where he specified that the eastern bank of the Wye should form the boundary. By the mid-eleventh century, most of Wales had become united under the king of Gwynedd, Gruffudd ap Llywelyn. In 1055, he marched on Hereford and sacked the city. He also seized Morgannwg and the Kingdom of Gwent, together with substantial territories east of
River Dee, Wales a mixed fishery with salmon and trout fishing, mostly in the upper waters and a good coarse fishery in the lower reaches. A major pollution incident in the middle reaches in the late 1990s did extensive damage to the fishery from which it is now largely recovered. River Dee, Wales The River Dee (, ) is a river in the United Kingdom. It flows through parts of both Wales and England, forming part of the border between the two countries. The river rises in Snowdonia, Wales, flows east via Chester, England, and discharges to the sea in an estuary between