The Normans, following their invasion of England in 1066, and the subsequent conquest of large parts of Wales, had proceeded towards North Wales in the late eleventh century.
While the Normans had experienced a setback in 1094, the Norman earls Hugh of Montgomery and Hugh d'Avranches finally manage to conquer North Wales and Anglesey in 1098, forcing Gruffudd ap Cynan, King of Gwynedd, to flee to Ireland.
The Norwegian king Magnus Barefoot goes on an expedition with a large fleet into the Irish Sea early in 1098, seeking to assert Norwegian rule over the Kingdom of the Isles.
After he has subdued most of the Isles and set up his base on Mann, he goes further south and appears with six ships (according to the English chronicler Orderic Vitalis), off the coast of Anglesey, only a few days after the Norman capture.
According to Orderic Vitalis, Magnus enters the Menai Strait with a red shield on the mast, which is 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 approaches Anglesey in June or July, the Normans do not permit him to land.
The fighting starts 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 prepare to attack the Norwegians, Hugh of Montgomery, who is fully armored except for an opening for his eyes, is shot through one eye with an arrow and dies instantly.
Contemporary non-Norse sources all agree that Magnus Barefoot himself was responsible for the shot, while the Norse sagas 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 realized 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.
