According to the traditional narrative of Denmark’s conversion, Christianization was first and foremost the work of a man named Ansgar (or Anskar), the first archbishop of Hamburg-Bremen in Germany. Ansgar was credited with having converted Denmark, starting with the king. Along the way, he founded churches, and even traveled to Sweden to attempt to convert the Swedes at the invitation of that country’s king. This story comes from the pens of clerics employed by the archbishopric of Hamburg-Bremen, who were motivated by the political desire to claim ecclesiastical authority over Scandinavia. Unsurprisingly, much of this story consists of exaggerations or outright fabrications.
Here’s what actually happened, as far as we can tell:
The first attempt to convert the Danes – or any of the Scandinavians – was made by the Franks in the early ninth century. Under Charlemagne’s leadership, the Frankish kingdom had recently conquered Saxony, the land immediately south of Denmark, and had brought the Saxons into the Christian faith through an exceptionally rapid and violent process – a stark contrast to the gradual, peaceful transition that occurred in most other parts of Europe.
Ansgar was sent north to begin converting the Danes. His only clear success was the conversion of Harald Klak, one of the competitors for the kingship of Denmark, in 810. But the conversion of “King” Harald meant little, because Harald was forced to flee Denmark when the power dynamics in the country shifted against him. He lived the rest of his life in the Frankish Empire, supported by a pension from the emperor.
In the ensuing decades, Frankish missionaries sent to convert Danish rulers failed, but along the way converted enough of the populace that a few churches were built and the rudiments of an ecclesiastical structure were put in place.
The first “proper” Danish king to become a Christian was Harald Gormsson, whose nickname was Harald Bluetooth. Harald ruled in the middle of the tenth century, and allegedly adopted the new religion after witnessing a Christian priest from Germany (but not from Hamburg-Bremen) hold a hot iron in his hand without suffering the merest burn. This miracle – and/or the political advantages mentioned above – persuaded him of the power of the Christian god, so he accepted baptism. In or around the year 965, Denmark officially became a Christian country. Harald Bluetooth was the first of a long and unbroken line of Christian kings of Denmark.