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 Dore the local geology combined with low rainfall. River Dore The River Dore (Welsh: "Afon Aur" lit: 'the River of Gold') is a tributary of the River Monnow in Herefordshire, England. It rises on Cusop Hill, in the foothills of the Black Mountains, close to the border between England and Wales. It flows for through the villages of Dorstone, Peterchurch, Vowchurch, Abbey Dore and Pontrilas, before reaching the Monnow near Llangua. The Monnow itself is a tributary which flows into the River Wye at Monmouth. The name Dore probably derives from the Welsh word "dŵr", meaning "water". The word was later