Olaf Haraldsson was born about 995 and raised on Ringerike by his stepfather Sigurd Syr. Like other sons of Norwegian chieftains he went raiding young — in the Baltic, in England, in France — and fought for the English king Æthelred against the Danes. Wintering at Rouen in 1013–14 he was baptised (the sources differ on the exact year), and he came home in 1015 resolved to rule all of Norway and to make it Christian.
He won the kingdom at the battle of Nesjar in 1016. With an English cleric, Bishop Grimkell, he set about building a Church in Norway, and the assembly at Moster in 1024 is remembered as the moment Christian law was accepted — though historians think some of the law later credited to him is younger. His methods were not gentle. The Catholic Church in Norway says it plainly: he offered 'gold, land and good gifts' to those who came over to him and threatened 'loss of property and life' to those who refused baptism.
In 1028 the Danish king Cnut, with the support of Olaf's own chieftains, took Norway, and Olaf fled to Sweden and on to Kievan Rus', where his brother-in-law Yaroslav the Wise ruled. In 1030 he came back with a small army and met a much larger force of farmers and chieftains at Stiklestad, on 29 July 1030, where he was killed. Snorri's saga, two centuries later, has the sun darken during the battle; the only eclipse over Norway that year fell on 31 August, and the darkness is best taken as part of the legend, while the date of 29 July stands in the Church's memory.
Within the year his enemies were telling of miracles. On 3 August 1031 Bishop Grimkell had the grave opened before witnesses: the body was found fresh, the hair and nails grown, and the bishop declared him a saint. The earliest witness is a skaldic poem composed about 1032, Glælognskviða, which already speaks of the incorrupt body and of the blind healed. His cult ran across the northern world — to churches of St. Olave in London and York, to Novgorod, to the Varangian guard in Constantinople — and Norway came to call him its 'eternal king'.
Nidaros Cathedral in Trondheim rose over his grave, and the pilgrim roads to it were among the great ones of medieval Europe. The Reformation ended that: in 1540 his silver shrines were broken up and some 95 kilograms of silver sent to the Danish king in Copenhagen; the body, carried off by Swedish troops in 1564 and brought back, was buried in the cathedral and in 1568, by royal order, the grave was filled with earth and left unmarked to stop the pilgrimages. No one has found it since. The pilgrim roads were reopened in 1997, Olsok is kept every 29 July at Stiklestad and Trondheim, and the Catholic cathedral of Oslo is dedicated to him.

