Dag Ringsson was a Norwegian chieftain from Oppland.According to Snorri Sturluson, Dag Ringsson was a descendant of Harald Fairhair. His family had settled in Sweden, where Dag was a nobleman at the service of the Swedish king. In 1026, King Olaf II of Norway had lost the Battle of the Helgeå, and in 1029 the Norwegian nobles, seething with discontent, rallied round the invading Cnut the Great of Denmark, forcing Olaf to flee.