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.