England–Wales border after Harold's death at the Battle of Hastings, Wales was again divided without a leader to resist the Normans. Immediately after the Norman conquest of England, King William installed one of his most trusted confidants, William FitzOsbern, as Earl of Hereford. By 1071 he had started the building of Chepstow Castle, the first castle in Britain built of stone, near the mouth of the Wye. It served as a base from which the Normans continued to expand westward into south Wales, establishing a castle at Caerleon and extinguishing the Welsh kingdom of Gwent. William also installed Roger de Montgomerie at
River Wye Gloucestershire, and Monmouthshire. The Wye abuts a range of other SSSIs in England and Wales, including the Upper Wye Gorge and Lower Wye Gorge. It is also a Special Area of Conservation and one of the most important rivers in the UK for nature conservation. It is an important migration route and wildlife corridor, as well as a key breeding area for many nationally and internationally important species. The river supports a range of species and habitats covered by European Directives and those listed under Schedule 5 of the Wildlife and Countryside Act 1981. In Powys the river lies within