Introduction
After converting to Christianity, Olaf Tryggvason renounced his career as a self-employed pagan pirate. But the Anglo-Saxon Chronicle tells us that six years later he felt free to ally himself with King Sweyn of Denmark, a Christian, and challenge Ethelred the Unready for the English crown.
IN this year [994] came Olaf and Sweyn to London,* on the nativity of St Mary,* with ninety-four ships; and they then continued fighting stoutly against the city, and would also have set fire to it. But they there sustained more harm and evil than they ever supposed that any citizens would be able to do unto them. But the holy mother of God, on that day, shewed her mercy to the citizens and delivered them from their foes.
And they then went hence, and wrought the utmost evil that ever any army could do, by burning, and plundering, and by man-slaying, both by the sea-coast and among the East-Saxons, and in the land of Kent, and in Sussex, and in Hampshire. And at last they took to themselves horses, and rode as far as they would, and continued doing unspeakable evil.*
That is, Olaf Tryggvason and King Sweyn ‘Forkbeard’ of Denmark. This was six years after Olaf’s baptism and his marriage to Norse-Irish princess Gyda: see The Baptism of Olaf Tryggvason and The Wooing of Olaf Tryggvason. Sweyn ousted Ethelred in 1013 but died the following year, and another Norwegian, Olaf Haraldsson, helped Ethelred briefly regain his crown. See The Day London Bridge Fell Down.
September 8th.
Sweyn was a Christian too, and indeed preferred English priests and bishops to those of the Holy Roman Empire on the Continent. In his own eyes Olaf was, therefore, backing a Christian king and backing the English Church, though his methods do leave something to be desired. Olaf and Sweyn eventually fell out, and Olaf died at the hands of Sweyn and his allies in the Battle of Svolder in the Baltic Sea in 999 or 1000.