Early Life and Conversion
Olaf was born around 995 in Ringerike, the son of Harald Grenske, a petty king of Vestfold, and Asta Gudbrandsdatter. As a young man he traveled to the Baltic region, Denmark, and England as a Viking. In 1008 he landed on the Estonian island of Saaremaa and defeated the Osilians, and skaldic poetry credits him with a seaborne attack on London Bridge around 1014.
He was baptized at Rouen in Normandy by Robert the Dane, archbishop of Normandy, while wintering with Duke Richard II. Orthodox accounts record some uncertainty over the timing, citing either a baptism in Norway around 998 or, more probably, the baptism at Rouen around 1010.
King of Norway
Olaf returned to Norway in 1015 and declared himself king, gaining the support of five petty kings of the Norwegian Uplands. In 1016, at the Battle of Nesjar, he defeated Earl Sweyn of the earls of Lade, who had been the de facto ruler. He founded Borg, later Sarpsborg, and consolidated more power than previous kings, subduing southern petty kings and asserting authority over the Orkney Islands.
In 1019 he married Astrid Olofsdotter, the illegitimate daughter of King Olof Skotkonung of Sweden. He also had an illegitimate son, Magnus, later known as Magnus the Good.
Promotion of Christianity
Olaf has traditionally been credited with leading the Christianization of Norway, working to establish the faith by demolishing pagan temples and founding churches, though modern scholars debate the extent of his actual role in the process. He brought Bishop Grimketel from England, who helped organize the Norwegian church, and is said to have focused on enforcing Christianity in inland areas where pagan practice remained stronger.
Opposition to his Christian reforms, together with his efforts to unify Norway under a single ruler, contributed to the discontent that ultimately turned many of his own subjects against him.
Exile and Death at Stiklestad
In 1026 Olaf fought at the Battle of the Helgea. By 1029 Norwegian nobles discontented with his rule backed an invasion by King Cnut the Great of Denmark, and Olaf was driven into exile, spending time in Kievan Rus.
He returned with an army, supported by the Swedish king Anund Jacob, to reclaim his kingdom, and met rebellious Norwegian nobles at Stiklestad on 29 July 1030. He was mortally wounded and fell on the battlefield. His death is attributed to opposition to both his Christian reforms and his efforts to unify Norway as a single nation.
Veneration
Bishop Grimketel canonized Olaf about a year after his death, on 3 August 1031, and Pope Alexander III confirmed the local canonization in 1164. Olaf came to be known as Rex Perpetuus Norvegiae, the Eternal King of Norway. In the Orthodox Church he is venerated as a holy martyr and right-believing king, counted among the pre-schism Western saints. His feast day is 29 July, celebrated in Norway as Olsok.
Relics & Shrine
Olaf's remains were enshrined at Nidaros Cathedral in Trondheim, built over his burial site, which became a major pilgrimage destination. Orthodox accounts relate that his body was found incorrupt and report that King Harald III found his hair and nails still growing some thirty-five years after his death. The exact position of the grave at Nidaros has been unknown since 1568. A relic, a bone from his arm, is kept in the crypt of Rouen Cathedral, where he had been baptized.