Battle of Anglesey Sound The Battle of Anglesey Sound was fought in June or July 1098 on the Menai Strait ( " Anglesey Sound " ) , separating the island of Anglesey from mainland Wales . The battle was fought between Magnus Barefoot , King of Norway , and the Anglo - Norman earls Hugh of Montgomery and Hugh d ' Avranches , and took place as part of Magnus Barefoot ' s expedition into the Irish Sea , which sought to assert Norwegian rule over the Kingdom of the Isles . Only a few days after the Normans had captured Anglesey from the Welsh , Magnus Barefoot appeared with some ships off the coast . Fighting soon began with arrows shot between the Norwegian ships and Norman forces on the shore , but as Hugh of Montgomery was hit with an arrow and killed , the Normans retreated back to England . The defeat of the Normans allowed for the return of the exiled Gruffudd ap Cynan , King of Gwynedd , who thereby regained control of his former lands . Background . Following their invasion of England in 1066 , and the subsequent conquest of large parts of Wales , the Normans proceeded towards North Wales in the late 11th century . While the Normans experienced a setback in 1094 , the Norman earls Hugh of Montgomery and Hugh d ' Avranches finally managed to conquer North Wales and Anglesey in 1098 , forcing Gruffudd ap Cynan , King of Gwynedd , to flee to Ireland . Early in 1098 , the Norwegian king Magnus Barefoot went on an expedition with a large fleet into the Irish Sea , seeking to assert Norwegian rule over the Kingdom of the Isles . After he had subdued most of the Isles and set up his base on Mann , he went further south and appeared with six ships ( according to the English chronicler Orderic Vitalis ) , off the coast of Anglesey , only a few days after the Norman capture . Battle . According to Orderic Vitalis , Magnus entered the Menai Strait with a red shield on the mast , which was the usual sign to signal peace and trade . While Magnus may have sought trade , or to get provisions for his ships , he may also have intended to take possession of the island as a base for further operations . When Magnus approached Anglesey in June or July , the Normans did not permit him to land . The fighting started with the two sides shooting arrows at each other , the Norwegians while still onboard their ships , and the Normans while standing on the shore . As the Normans prepared to attack the Norwegians , Hugh of Montgomery , who was fully armoured except for an opening for his eyes , was shot through one eye with an arrow and died instantly . Contemporary non - Norse sources all agree that Magnus Barefoot himself was responsible for the shot , while the Norse saga s are somewhat less inclined to attribute the decisive shot to Magnus alone , noting that his shot hit Hugh almost simultaneously with that of another of his men . Since some sources indicates that Magnus regretted the deed when he realised who he had killed , Magnus may originally have been interested in alliances with the Normans . The Normans retreated from Anglesey to England following the defeat . Aftermath . Although the Welsh considered the Norwegians their liberators following the Norwegian victory against the Normans , Magnus regarded Anglesey as part of the Kingdom of the Isles and took the island as a Norwegian possession . Since the Norwegians never settled on the island , Anglesey reverted to Welsh control when Gruffudd ap Cynan returned from Ireland in 1099 . The Norwegian control was at best nominal thereafter , but as Gruffudd awarded Magnus with great rewards and honour , and during Magnus ' second expedition in 1102 allowed him to cut as much timber as he wanted , Magnus may possibly have reasserted the overlordship over Gruffudd formerly held by Godred Crovan , and thereby received the submission of Gwynedd .