Harald Bluetooth being baptized by Bishop Poppo the missionary 1200 CE

"Emperor Otto 1. the Great, died in May 973 and was succeeded by his son Otto 2. Harald Bluetooth, who was now sole king of Denmark, must have thought that now the chance was there with a new and inexperienced emperor. Harald took without problems Hedeby, which was an old Danish town, founded by King Godfred in the year 808. 

Adam of Bremen recounts what happened in Bishop Adeldags time around the year 973: 

"After he then had subjected nearly all the kingdoms that after Karl's death had broken away, he took up arms against the Danes, those his father had already subdued. The latter was decided on war, had in Hedeby massacred Otto's envoys together with the margrave and utterly destroyed the Saxon colony. For in this respect to avenge the injury the king with an army immediately pushed into Denmark, and as soon as he had crossed those of the Danes at Slesvig formerly erected borders, he devastated with fire and sword the country right up to the outer sea that divides the Danes from the Normans, and to this day after the king's victories is called Ottesund. " - "After that, on both sides, there had been fought bravely, the Saxons won the victory, and the conquered Danes retreated to their ships. At last, they agreed on the peace terms: Harald accepted Otto's conditions, he received from him his kingdom and promised to let Christianity apply in Denmark. And immediately Harald himself was baptized along with his wife Gunhild and their young son, whom our king hold during the baptism and named Svend Otto."

-taken from dandebat.dk link below

Harald Bluetooth being baptized by Bishop Poppo the missionary 1200 CE.

Source/Quote:

http://www.dandebat.dk/eng-dk-historie19.htm