Robert of Rhuddlan Robert of Rhuddlan ( died 3 July 1093 ) was a Norman adventurer who became lord of much of north - east Wales and for a period lord of all North Wales . Robert was the cousin of Hugh d ' Avranches , 1st Earl of Chester , and appears to have come to the Welsh Marches before 1066 in the service of Edward the Confessor . Hugh became Earl of Chester in 1070 , and Robert appears to have been appointed Hugh ' s " commander of troops " in 1072 . He immediately began hostilities with the Welsh , and having captured land in the cantref of Tegeingl ( North East Wales ) he built a Motte - and - bailey castle at Twthill near Rhuddlan , holding the lands as a vassal of Earl Hugh . When Gruffydd ap Cynan tried to recover the throne of Gwynedd from Trahaearn ap Caradog in 1075 , Robert assisted Gruffydd by providing Norman troops . Later the same year Trahaearn counter - attacked and drove Gruffydd to seek refuge in Ireland , but Robert was able to take advantage of the civil war to seize the cantref s of Rhos and Rhufoniog and to build another castle at Deganwy . He now ruled most of northern Wales east of the River Conwy . In 1081 , Trahaearn ap Caradog , who had been able to prevent Robert from encroaching further west , was killed in the Battle of Mynydd Carn by Gruffydd ap Cynan and his allies . Gruffudd now became king of Gwynedd , but shortly thereafter he was captured by treachery by the Normans at Rhug near Corwen . Gruffydd was imprisoned by Earl Hugh in his castle at Chester , but Robert seems to have been responsible for his capture , since he was the one to claim Gruffydd ' s lands . Robert built castles at Bangor , Caernarfon , Aberlleiniog and elsewhere . In the Domesday Book he is said to hold all of North Wales apart from lands belonging to the bishoprics of Bangor and St Asaph , holding these lands directly of the king and not as in fief from Earl Hugh . He was liable to an annual rent of £40 . On William the Conqueror ' s death in 1087 , war broke out between his sons . Robert supported the elder son , Robert Curthose and in 1088 he and his troops were involved in the siege of Rochester . They were however obliged to surrender to the forces of William Rufus . Robert ' s career was brought to an abrupt end in 1093 at the beginning of the great Welsh revolt . He was enjoying a noontide nap in his castle at Deganwy when the news was brought to him that Welsh raiders had landed in three ships underneath the Great Orme and pillaged his lands . Some sources say that these raiders were led by Gruffydd ap Cynan , who had escaped from captivity in Chester . The raiders had beached their ships and were busy loading the plunder . Robert despatched messengers to gather his troops and hastened to the Great Orme , where he found that the rising tide was about to allow the Welsh to refloat their vessels and get away with the loot before Robert ' s troops could appear . In a fury , Robert rushed down the slopes to attack them , followed only by his armour - bearer . He was killed by a volley of javelins , and the raiders sailed off with his head attached to the mast of one of the vessels . Robert ' s lands in Gwynedd were now taken over by Earl Hugh of Chester , but the Welsh revolt of 1094 led by Gruffydd ap Cynan resulted in the loss of most of this territory .