Olaf Cuaran

Sihtric[?], Olaf's father, ruled Deira, a part of Northumbria, until his death in 927. Upon Sihtric's death, Athelstan annexed Deira and Olaf fled to Scotland. Until 937, he spent time in Scotland and Ireland and participated in the Battle of Brunanburh as part of the defeated alliance.

Athelstan died in 939 and Olaf Guthfrithson, king of Dublin at the time, invaded Northumbria and compelled Edmund, Athelstan's successor, to surrender Deira. When Olaf Guthfrithson died in 942, Olaf Cuaran succeeded him, finally recovering the throne of his father in addition to the throne of Dublin. Two years later, however, Edmund expelled him from Northumbria and Olaf was left with only Dublin.

Olaf managed to regain his lands in Northumbria in 949, only to be expelled again in 952, this time by Erik Bloodaxe[?].

In 980, Olaf suffered a massive defeat at the Battle of Tara[?], which destroyed the power of the Danes in Ireland. He went to Iona and probably died there in 981.

References

Ketil Ken Nygaard's Genealogy

http://nygaard.50g.com/files/2507.htm