Charlemagne strides across the early medieval period like a colossus. He spent his life trying to piece back together the shattered fragments of the Western Roman Empire and was crowned by the Pope as the first Holy Roman Emperor. 

However, to borrow Voltaire's great quip, this new creation was "neither Holy, nor Roman, nor an Empire." 

Nevertheless, Charlemagne absorbed a considerable area of what had been the Western Roman Empire and brought it under his control. 

Yet, despite all the battlefield successes and glories he won, there lay an inbuilt weakness – he simply could not defend all his borders. 

Following his destruction of the Saxons, Charlemagne soon realized that his northern border touched the southern reaches of Scandinavia.

While Charlemagne was forging an empire, new threats appeared from the cold north. From the end of the 8th century, predatory Viking raids soon plagued much of the Holy Roman Empire, especially in Frisia and Francia. 

With the defeat of the Saxons, Charlemagne soon found himself without a "buffer zone," his empire now bordering the land of the Danes. 

By the time he died in 814, Viking activity was so intense and devastating that his son and heir, Louis the Pious, was desperate for a solution. 

As the king of Jutland, Harald Klak would have been familiar with Ribe, one of the region's most important trade and political centers during the Viking Age. Photo: Frank Bach / Shutterstock

Klak enters the historical record 

Frustratingly for academics, history lovers, and writers at The Viking Herald, we have only fragments of information about many rulers in the early medieval period. 

Harald Klak is no exception. 

The man who would be King of Denmark (or was he? More on that later) and be recognized as the first Christian king in the Nordic region is believed to have been born sometime around 785. 

Though this was shortly before the famous Viking raid on Lindisfarne – which is traditionally considered the start of the Viking Age – new research has shown that Viking activity had been occurring since at least the mid-8th century. 

Klak appears to have been born into some sort of ruling elite in Jutland, southern Denmark, with many siblings. 

It was these siblings that would ultimately lead to Klak's first mention in the historical chronicles. 

Upon their father's – and the ruler of Jutland's – demise, the Royal Frankish Annals mention that Hemming, a King of the Danes (probably Klak's father), had died and there were problems with succession. 

A brother of the ruler and the ruler's son were both vying for the throne, resulting in a bloody civil war in which Harald's forces won in 812. 

However, there is divided academic opinion on whether Klak ruled over all of what would become the medieval kingdom of Denmark or just Jutland.

The demise of Charlemagne would provide the context for the next historical mention of Klak. 

In 813, there was a general assembly of the nobility at Aachen to anoint Charlemagne's son, Louis, as co-emperor and successor and for his grandson, Bernard, to rule over Italy. 

While one royal succession was secured, another in Denmark was falling apart. 

Despite being ensconced on the throne, familial rivalry and jealousy saw Harald fend off more threats to his throne, and a new civil war, at least in Jutland, started. 

By the time Louis ascended to the throne in 814, Harald was forced to flee and seek refuge in the realm of the Franks. 

It was his time as a political exile in Louis' court that would shape the future of Denmark. 

The city of Aachen served as a haven for Harald Klak, where he sought Louis the Pious' support, leading to his baptism and a crucial alliance in his quest to regain power in Denmark. Photo: CEphoto, Uwe Aranas / Wikimedia Commons (CC BY-SA 3.0)

A refugee and a convert 

It was during his time in exile at the court of Louis the Pious that Harald Klak made a fateful decision. 

In return for Louis's promise of arms and men to try and reclaim his throne in the north, Klak agreed to convert to Christianity. 

With Louis as his godfather, the Danish king was baptized, and a spiritual, as well as political, relationship between the two rulers was forged. 

Soon, Louis organized a considerable force to march with Klak northward, but the harsh winter conditions forced them back.

Gathering a new force with help from his allies, Louis organized another expedition for Klak to try and seize back the Danish throne. 

Among the soldiers and warmongers were people with a more peaceful mission. 

Due to Klak's recent conversion, there was a group of monks amongst them, including Anskar (known as the "Apostle of the North" and later sainted). 

In 819, Klak seems to have won back some territory, co-ruling with Horik. 

It was during this time that the first church in the Nordic region was built at Hedeby, and the "top-down" proselytization of Denmark began. 

However, by 823, Louis was made to mediate again as the two co-rulers appeared to be on the path to another bloody civil war. 

A solution was finally sorted whereby Klak would visit the emperor in 826, accompanied by a great number of his political elites, many of whom were baptized in Mainz Cathedral. 

In return, Louis granted Klak land in Frisia; it was his personal fiefdom, but he had the responsibility for the protection of its borders. 

Historians believe that this foreshadows a later Frankish ruler granting land at the edges of his realm's border to a Scandinavian warrior to fend off further attacks from Vikings. 

In the time of Harald Klak, Hedeby stood not just as a significant trade center but as a cultural crossroads in the Danish kingdom, playing a vital role in the maritime and commercial activities that defined the Viking Age. Photo: Matthias Süßen / Wikimedia Commons (CC BY-SA 4.0)

Later life and legacy 

Scouring the historical chronicles, Harald Klak seems to have disappeared into oblivion from the late 820s. 

The last mention of him is in 827, when he was dethroned once again by familial rivals and came to the court of Louis. 

His brother, Hemming, was said to have died in a Viking attack in the territory of Frisia that Klak was awarded in 837, and there is a possibility that he too was killed in this attack. 

Some historians have also speculated that following his last exile from Denmark, he may have returned, but not with an army, and lived out his years peacefully there. 

While Harald Klak's grip on the throne was always tenuous and short-lived, he remains one of the most consequential rulers of the entire Viking Age

His exile to the Frankish court and subsequent conversion to Christianity signaled a turning point in the history of Scandinavia. 

Henceforth, rulers and political elites would convert, even if this process took centuries

The Old Norse religion would, from this point on, slowly decline. 

The construction of a Christian church at Hedeby, along with the monks he brought with him from the Frankish court, established a Christian presence in the very heart of Scandinavia. 

From here, the holy mission of the monks to save these pagan souls would begin. 

His relationship with Charlemagne and Louis the Pious foreshadowed how later Scandinavian rulers, Viking or not, were now part of a broader European political network. 

All this from a man whose birthdate is still truly unknown.

For more information on Harald Klak, visit the National Museum of Denmark here

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