In 920 the "Annals of Ulster" report that Sitric left Dublin "through the power of God". Sitric travelled to Northumbria where he assumed the kingship of Northumbria, succeeding his kinsman Ragnall who died the following year. Sitric was followed as King of Dublin by his brother or cousin Gofraid ua Ímair. In 920 Ragnall had submitted to Edward the Elder, King of the Anglo-Saxons. That same year, following his departure from Dublin, Sitric led a raid in Davenport, Cheshire, in violation of the terms of submission agreed between Ragnall and Edward. Smyth has suggested that this was an act of defiance by Sitric, indicating to Edward that he would not submit to him like Ragnall.