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 River Wye The River Wye () is the fifth-longest river in the UK, stretching some from its source on Plynlimon in mid Wales to the Severn estuary. For much of its length the river forms part of the border between England and Wales. The Wye Valley (lower part) is an Area of Outstanding Natural Beauty. The Wye is important for nature conservation and recreation. The meaning of the name is not clear. Possibly the earliest reference to the name is "Guoy" in Nennius' early 9th Century "Historia Brittonum" and the modern Welsh name is "Gwy". The Wye was much later