The Vikings Of Danish King Harald Bluetooth, Possibly Polish Mercenaries
Harald ‘Blåtand’ Gormsson (known in Old Norse as Haraldr blátǫnn Gormsson, in Danish as Harald Blatant Gormsen and English as Harald Bluetooth) was likely born in 935 as the son of King Gorm the Old (Gorm den Gamle) and of Thyra Dannebod. Harald Bluetooth is one of the most renowned Vikings of all time and an iconic personality of the Kingdom of Denmark, having managed to unify Denmark and Norway, converting Denmark to Christianity and building the famous ring-shaped fortresses, some of which are planned to be submitted to UNESCO as World Heritage Sites. These ring-shaped citadels (known as ‘trelleborgs’) might have had different purposes, such as working as trade posts or as supplying military centres for the Norse invasion of England in the early 11th century.

Map depicting the territorial extent of Harald Bluetooth’s kingdom. Image source: www.wideurbanworld.blogspot
Until quite recently, it was widely assumed that Harald Bluetooth’s army consisted exclusively of Danish Vikings, but a group of international researchers from three universities determined the origin of some of the Norse monarch’s soldiers back in 2011. Archaeologists from Aarhus University (DK), the University of Copenhagen (DK), and the University of Wisconsin-Madison (US) examined a number of forty-eight skeletons from the burial mound at Trelleborg, situated in the proximity of the town of Slagelse, West Zealand. From the skeletons found at the burial mound near the circular Viking Age fortress of Trelleborg, multiple tooth enamel samples were collected and were carefully analysed using a new method called ‘strontium isotope analysis’.

Portrait of King Harald Bluetooth. He reigned over Denmark from circa 958 to circa 986, and over Norway from circa 970 to circa 976/986. Image source: www.geni.com
The strontium isotope analysis made it possible to discover the fact that more than half of the skeletons did not originate in Denmark. Nonetheless, the researchers were not able to trace the precise geographic origin of the remains, but considering previously unearthed archaeological discoveries at Trelleborg (most notably pottery and weapons), it is quite possible that the deceased came from either Norway or from the southern coastline of the Baltic Sea — modern-day Poland.
According to Dr Andres Siegfried Dobat, an archaeologist at the Section for Prehistoric Archaeology, Aarhus University, the foreign mercenaries influenced the development of the Danish national state — not just throughout Harald Bluetooth’s reign, but also in the centuries to come. Dr Andres Siegfried Dobat bases his theory on information from a particular rune stone from Egå, which mentions an individual by the name Ketill the Norwegian, who was probably Bluetooth’s housecarl (bodyguard).
Pottery of Slavic origin was also discovered in other trelleborgs throughout Denmark. Additionally, a battle axe encrusted with silver and gold which was found in an individual burial mound at Trelleborg, West Zealand, might well indicate the origin of the deceased warrior as the early Polish kingdom or the legendary Jomsborg — the fabled Viking Age fortress located on the southern coastline of the Baltic Sea.
The results of this research were published in the British journal Antiquity, one of the most prestigious archaeological publications in the world.
Documentation sources and external links:
- Harald Bluetooth’s Vikings were Polish mercenaries on www.au.dk
- Who was in Harald Bluetooth’s army? Strontium isotope investigation of the cemetery at the Viking Age fortress at Trelleborg, Denmark | Antiquity, Volume 85, Issue 328; June 2011, pp. 476-489 on www.cambridge.org
- Harald Bluetooth on www.wikipedia.org (in English)
- Jomsborg on www.wikipedia.org (in English)