Þangbrandr's origins are uncertain. According to some sources, he was the son of an otherwise unknown Vilbaldus, count of Saxony or of Bremen. But he is also said to be Flemish. He may have been a clerk to the bishop of Bremen. However that may be, his name seems to be of German origin, and may come fromOld High German*Dankbrant.
Encounter with Óláfr
The Bishop of Bremen was invited to England by the Archbishop of Canterbury, and Þangbrandr went with him. In England, Þangbrandr was offered a shield with a crucified Christ drawn on it. When they returned to Saxony they met Óláfr, who saw Þangbrandr's shield and was pleased with it. The Þangbrandr gave Óláfr the shield and, in return, the king promised to help and protect him in case he would need it.
After fighting over a woman with one of the Emperor's men and killing him, Þangbrandr was forced to flee from the land. He joined Óláfr in England, who took him into his service. When Óláfr came back in Norway, Þangbrandr was put in charge of baptizing the people in Hordaland. But he soon fell short of money and began to rob those who were still pagans.
Mission in Iceland
As a penance, Óláfr sent him to Iceland, where Þorvaldr Kodránsson and Stefnir Þórgilsson's missions had failed. Þangbrandr's mission began in 997. He first succeeded in converting Sídu-Hallr Þorsteinsson. He travelled around the country and several other prominent Icelanders agreed to be baptized or at least to receive prima signatio. But he had more opponents than followers. The difficulties he came up against are especially described in Brennu-Njáls saga in a "lively, although probably exaggerated" manner. He was challenged to a duel by Þorkell whom he defeated, although he carried a crucifix rather than a shield. Some of his enemies paid a sorcerer to get rid of him. The sorcerer made a sacrifice and the ground opened up under Þangbrandr. His horse was swallowed up but he escaped. The priest killed the skaldVetrliði Sumarliðason who had composed defamatory verses about him. He also killed another skald, Þorvaldr veili, who had gathered a troop to slay him. Steinunn, Hofgarða-Refr's mother, preached the old faith to him, trying to demonstrate the superiority of Thor over Christ. Þangbrandr then caused the death of a berserker. He was eventually outlawed because of the men he had killed. After two years in Iceland, he went back to Norway and explained he had failed: When Óláfr learned that, he got angry and threatened to hurt or kill all the pagan Icelanders who were in town at that time. But Gizurr the White Teitsson and Hjalti Skeggjason, who had been converted by Þangbrandr, talked him out of it. They explained that Þangbrandr had failed because he had proceeded with violence and murders and they committed themselves to preaching Christian faith in Iceland. The conversion of Iceland was eventually decided at the next Alþing.
