Fierce warrior, conqueror and king, Björn Ironside is one of the towering figures of the Viking age. Yet, at the same time, it’s hard to separate the hard historical truths from the awesome legends that have developed around the fabled Norseman. Let’s take a look at the stories and sources that built Björn up over the centuries.

The son of a towering figure

One of the few things we know for certain about Björn Ironside is that he lived in the 9th century. His true parentage is unknown, but according to Norse lore, he was a son of Ragnar Lothbrok – the iconic king of Sweden and Denmark.

Ragnar Lothbrok is a semi-legendary figure. As with Britain’s King Arthur, he may have been inspired by a real-life warrior – possibly a Viking chieftain named Reginherus who plundered Paris in 845 AD – but he really owes his fame to the many mythical adventures described in medieval literature.

These include his wooing of a beautiful maiden by slaying a fearsome serpent, his battles against foreign invaders who tried to usurp his kingdoms, and his own extravagant death in a snake pit during a failed invasion of England. As the lore tells us, Björn Ironside proved to be a chip off the old block.

Early accounts of Björn Ironside

One of the first depictions of Björn can be found in the writings of the 11th-century Benedictine monk, William of Jumièges. He tells of a curious custom among Danish kings of the era, which was to exile their own sons from their kingdoms so they couldn’t be potential threats to the throne. According to William, Ragnar Lothbrok was a stickler for tradition, throwing Björn out of Denmark after becoming king.

The exiled Björn made himself busy in classic Viking fashion by taking his men on a pillaging trip in West Francia (modern-day France). Historical records corroborate William’s account of Björn raiding this region in the mid-9th century, and we know that he battled the forces of West Francia’s monarch, Charles the Bald. He later forged an alliance with Charles to keep the peace, though West Francia and the Vikings came to blows many more times in the years that followed.

William of Jumièges and other early medieval sources also describe Björn’s exploits in the Mediterranean. Here, he went pillaging in partnership with Hastein, an older Viking who was described as ‘mightily cruel’, ‘pestilent’, ‘given to outrage’ and an all-round ‘fomenter of evil’. During one escapade, they tricked their way into the city of Luna, in modern-day Italy, by claiming that Hastein was on his deathbed and wanted to convert to Christianity. On being allowed into Luna by the trusting locals, Hastein and his men proceeded to devastate the city.

Björn and his cunning mentor parted ways after their violent Mediterranean odyssey, with William of Jumièges telling us that Björn returned to northern Europe where he died. But this was far from the last we’d hear of Björn in medieval literature.

Björn the savage avenger

Much 'Björn lore' comes to us from a saga written hundreds of years after William of Jumièges’ account. Dated to around the late 13th or early 14th century, The Tale of Ragnar’s Sons is an Icelandic yarn that serves up the juicy exploits of Björn and his warrior brothers.

It talks about the boys ‘raiding far and wide’, and being so determined to take territory that they even did bloody battle with the king of Sweden, who happened to be an ally of their own father. Two of the brothers died, leading to Björn and the other siblings pledging to bring ‘various vile torments’ to the Swedish king. Together with their mother Queen Aslaug, who ‘wore armour herself and commanded the army’, they poured into Sweden, plundering and burning settlements, and killing the king.

According to the saga, Ragnar was ‘less than happy’ with this turn of events. But he soon came to a sticky end himself, being thrown into that aforementioned snake pit while trying to defeat an English king, Ælla of Northumbria.

Once again, Björn and his brothers were roused to vengeance, launching a massive invasion of England and eventually capturing Ælla himself. As the saga tells us, they tortured and killed him using the grisly blood eagle method, cutting open his back and pulling the ribs and lungs out from behind to create ghoulish wings.

It’s impossible to say whether this really happened. Certainly, Anglo-Saxon sources say that Ælla’s death was far less outlandish, with the king simply being slain in battle. Whatever the precise details, it is a historical fact that a Viking coalition known as the Great Heathen Army did invade England in the mid-9th century, conquering much of the land. It’s this invasion that is so colourfully dramatized by the Icelandic saga.

Björn in the Gesto Danorum

Another key source for all things Björn is the Gesto Danorum, a 13th-century Danish chronicle by historian Saxo Grammaticus. In this version of events, Björn helped his father Ragnar Lothbrok invade Sweden in an overwhelming show of force and was awarded the throne of Sweden by Ragnar as a reward. Saxo Grammaticus also provides his own account of the Great Heathen Army invasion of England, again framing it as a revenge mission by Björn and his brothers.

Perhaps the standout contribution of the Gesto Danorum is that it explains Björn’s distinctive name. While recounting the invasion of Sweden, Saxo Grammaticus tells us that Björn, ‘having inflicted great slaughter on the foe without hurt to himself, gained from the strength of his sides, which were like iron, a perpetual name: Ironsides.’