ANLAF, or OLAF (d. 981), king of the Danish kingdoms of Northumbria and of Dublin, was a son of Sitric, king of Deira, and was related to the English king ^thelstan. As his name indicates he was of Norse descent, and he married a daughter of Constantine II., king of the Scots. When Sitric died about 927 iEthelstan annexed Deira, and Olaf took refuge in Scotland and in Ireland until 937, when he was one of the leaders of the formidable league of princes which was destroyed by ^thelstan at the famous battle of Brunanburh. Again he sought a home among his kinsfolk in Ireland, but just after ^thelstan's death in 940 he or Olaf Godfreyson was recalled to England by the Northumbrians. Both crossed over, and in 941 the new English king, Edmund, gave up Deira to the former. The peace between the English and the Danes did not, however, last long. Wulfstan, archbishop of York, sided with Olaf; but in 944 this king was driven from Northumbria by Edmund, and crossing to Ireland he ruled over the Danish kingdom of Dublin. From 949 to 952 he was again king of Northumbria, until he was expelled once more, and he passed the remainder of his active life in warfare in Ireland. But in 980 his dominion was shattered by the defeat of the Danes at the battle of Tara. He went to lona, where he died probably in 981, although one account says he was in Dublin in 994. This, however, is unlikely. In the sagas he is known as Olaf the Red.
This Olaf must not be confused with his kinsman and ally, Olaf (d. 941), also king of Northumbria and of Dublin, who was a son of Godfrey, king of Dublin. The latter Olaf became king of Dublin in 934; but he was in England in 937, as he took part in the fight at Brunanburh. After this event he returned to Ireland, but he appears to have acted for a very short time as joint king of Northumbria with Olaf Sitricson. It is possible that he was the " Olaf of Ireland " who was called by the Northumbrians after thelstan's death, but both the Olafs appear to have accepted the invitation. He was killed in 941 at Tyningham near Dunliar.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)