Thanks to Bluetooth technology, every day people all over the world can connect wirelessly to listen to music, browse podcasts or watch movies. In the mid-1990s, its developer, Intel engineer Jim Kardach, was trying to come up with a name for this new technology. He was reading Viking history at the time and was intrigued by a runic stone praising the exploits of a 10th-century Danish king named Harald Bluetooth.
The stone described how Bluetooth brought the Danes together as one people and took over Norway. Kardach wrote that he thought the king’s name would be a good code name for the program. Other names were considered, but the nickname of the Viking monarch stuck. Bluetooth technology set out to conquer and connect the modern world, just as King Bluetooth connected and conquered many parts of Scandinavia more than a thousand years ago.
The birth of a dynasty
Harald Bluetooth’s life spanned the 10th century. During his 30-year reign, he invaded Norway, completed the conversion of Denmark to Gormssonian Christianity and built castles to glorify his name. Although his life would end in strife with his son Sweyn Forkbeard, his dynasty remained intact: His grandson Canute would later rule England, Denmark and Norway.
The name Bluetooth comes from Blåtand, which means “blue tooth” or “dark tooth” in Old Norse. Tradition says the nickname comes from the fact that the king’s teeth were blackened or bad, but there is no conclusive evidence of tooth structure.
Bluetooth had another name: Harald Gormsson, or son of Gorm. Exactly how his father Gorm came to power is unclear. He seems to have been a native Jutlander. In 936 AD, Gorm took control of northern Jutland from the Swedes and established a kingdom centered on the town of Jelling.
Gorm’s efforts to retain this kingdom and pass it on to his heir reflect a general trend in 10th century Scandinavia. Viking kingdoms had emerged in the preceding centuries around the North Sea on the back of wealth acquired through plunder. Then, in the 900s, they began to develop into centralized monarchies. What Gorm started in Jelling was consolidated by Bluetooth and his heirs. This Jelling Dynasty was also shaped by another important transformation of the 10th century: the Christianization of Scandinavia.
The Bluetooth saga
The two famous Runic stones in Jelling were impressive monuments to a new and stable form of government. The older and smaller of the two stones was inscribed by the pagan Gorm in memory of his wife Thyra, who was also the mother of Bluetooth. The larger stone was erected by Bluetooth. The engraving of “Christ hanging from a tree” on one side of this stone is the oldest visual depiction of Christ in Denmark. On the other side is the Runic inscription that centuries later would inspire the creator of Bluetooth technology: “Sá Haraldr es sér vann Danmork alla auk Norveg auk dani gærði kristna” (“Harald won all of Denmark and Norway for himself and made the Danes Christians”).
The claims inscribed in the Jelling Stone are, of course, propaganda. For a more detailed picture of Bluetooth’s successes and failures, historians turn to various medieval sources. One important document is a saga written in Iceland in the 13th century by Óláfr Þórðar-son, the nephew of Snorri Sturluson, another famous historian of the Vikings. Óláfr’s account, entitled “The Legend of Knýtlinga”, begins with the accession of Bluetooth: “He was a strong ruler and a great leader in battle.”
The saga then tells how Bluetooth set his sights on the kingdom of Norway, ruled by his nephew Harald Gráfeldr (Graycloak). The historical record suggests that Bluetooth conspired against Gráfeldr, who was invited to Denmark and assassinated there. Following the death of the Norwegian king, Bluetooth invaded Norway with his army; appointed Håkon Jarl as de facto king; and then forced the entire country to pay him tribute.
Transforming the King
To the south, Denmark bordered a much more powerful state than the Viking kingdoms: The Holy Roman Empire. The emperors had been fighting the Germanic and Slavic peoples for decades under the pretext that they were pagans who needed to be converted to Christianity. This was also the justification Emperor Otto II used when he attacked Bluetooth in 974, a year after Bluetooth had settled in Saxony.
According to the Legend of Knýtlinga, Otto “attacked the Danish king and tried to Christianize the Danes, but the Danish king had no intention of embracing the Christian faith and confronted Otto with his army”. With the support of Norwegian reinforcements, Bluetooth was able not only to thwart Otto’s attack, but also to capture the area south of the border. However, after the Norwegians withdrew, Otto regained the lost territory and even advanced north of Danevirk, the defensive line of walls and ditches that was the boundary between Christian and pagan lands.
The saga creates confusion about when Bluetooth was Christianized and whether Otto’s attack was religiously motivated. It is likely that the religious conversion took place in 965, several years before Otto’s attack. The most detailed surviving account is in the “Res gestae Saxonicae”, written in the late 10th century by the Saxon historian Corveyli Widukind, a monk from northern Germany. Widukind notes that even before the conversion of Bluetooth, the Danes recognized Jesus as a god, while worshipping their own gods, whom they believed to be more powerful. According to Widukind, Bluetooth welcomed a priest from Cologne named Poppo, who talked to him about faith:
Poppo explained that there is only one true God, that there is God, the Father, as well as his only son Jesus Christ and the Holy Spirit, and that the Danish gods are not really gods but demons. King Harald, who was quick to listen and slow to speak, asked Poppo if he would like to demonstrate this belief physically. Poppo agreed without hesitation. The king ordered a piece of iron to be heated and asked Poppo to carry it. Without hesitation, the priest of Jesus carried the iron to the place the king had ordered. The priest then showed everyone his unharmed hand… The king then decided that Christ must be worshipped as the only God. He ordered all his subjects to give up their idols and pay homage to God’s priests and servants.
Resistance against religion
But the conversion to Christianity was not smooth. According to the Knýtlinga Legend, Bluetooth forced the Norwegian king Hékon Jarl and his men at the Danish court to be baptized. He then sent Hékon Jarl with priests to Norway with the task of baptizing all Norwegians.
But Hékon Jarl was not impressed by the new religion. After leaving the Danish court, he renounced his Christian faith and returned to Norway, where he began offering lavish sacrifices to the Norse gods. Bluetooth was furious and led an attack that devastated the Norwegian coast. Only when Bluetooth’s forces returned to Denmark did Hékon Jarl regain control of Norway.
The road to Christianization was not smooth. In another episode of The Legend of Knýtlinga, despite his Christian fervor, Bluetooth himself had not completely abandoned his old beliefs. As he pondered whether to attack Iceland, he did not pray to the Christian god for guidance, but instead ordered “a sorcerer to go to Iceland and find out what he could tell him”. When the wizard returned with the news that the island was far away and in any case inhabited by all sorts of monstrous creatures, Bluetooth shelved his invasion plans.
Civil war in Denmark
Bluetooth was known for its security measures to protect its territory. Following threats from attacks by the Holy Roman Emperor, Bluetooth built numerous circular fortifications. These are now known as the Circular Viking Castles or Trelleborg-style fortresses. Building defensive structures on such a large scale required the labor of warriors who normally formed the retinue of nobles.
Unhappy at the loss of their men, the nobles were unhappy with Bluetooth, who they believed was abusing his power. This set the stage for the end of Harald Bluetooth’s reign. When Bluetooth’s son Sweyn was still young, he demanded a share of the kingdom, but his father refused. According to the Knýtlinga Legend, “As Sweyn was the son of a concubine, his father had no great affection for him and refused to give him any land to rule”. When Sweyn reached adulthood, he decided to act as Vikings always did, and after gathering several ships and a strong band of supporters, probably recruited from his father’s opponents, he started raiding expeditions in and around Denmark.
Bluetooth attacked his son’s forces with an army. After several skirmishes, the situation turned into a civil war. In one battle, Bluetooth’s troops finally defeated Sweyn’s forces, but Harald was wounded in the fighting. He died shortly afterwards in November 987. Harald is believed to be buried in Roskilde church. If so, Harald was the first Danish king to be buried in holy ground.
Bluetooth’s deep-rooted heritage
When his son ascended to the throne as Sweyn I, conflicts with the nobility subsided. During the period of relative peace that followed, the castles of Bluetooth were abandoned because they were costly to maintain. A ruthless warrior king, Sweyn Forkbeard devoted much of his reign to raids on England.
The world that Harald Bluetooth helped create continued to take shape during the reign of Sweyn I, whose fellow rulers in Norway and Sweden were all Christian kings at the time. The Scandinavian world, including Iceland, which converted to Christianity around 1000 AD, was being integrated into the spiritual map of Europe.
Bluetooth’s grandson Estrid gave his name to the House of Estridsen, which ruled Denmark until the 15th century and can be traced back to the current queen of Denmark, Margrethe II. The exploits of Bluetooth’s descendant Knútr inn ríki, better known as Knut, would have far-reaching consequences for English history.
The raids into England by Knut’s father, Sweyn I, had forced King Ethelred the “Unsupplied” to flee in 1013. This gave Sweyn a clear path to the throne as a short-lived king of the English. Following the death of his father in 1014, Knut was duly proclaimed king of the English and was forced to retreat to Denmark by the returning Ethelred. Gathering a fleet, Knut and his forces returned to England in 1016, defeating Ethelred’s son and successor Edmund Ironside.
As the new king of England, Knut stopped the Viking raids and ushered in a twenty-year period of stability and prosperity. Two years later he succeeded his brother as king of Denmark and expanded his territory. By 1028, the Jelling dynasty, united by Harald Bluetooth, stretched from southwest England to the far northeast of Norway.
Prepared with the help of National Geographic magazine / November 30, 2023.