In Scandinavian legend, Björn Ironside was the son of Viking chieftain Ragnar Lothbrok who led successful raids across Europe in the ninth century C.E. before becoming a ruler of Sweden and Norway and founding the royal Munsö Dynasty.

History ChannelAlexander Ludwig portrays Björn Ironside in the History Channel show Vikings.
The Vikings certainly weren’t lacking for esteemed warriors, but few reached the renown of Bjorn Ironside. Like his father Ragnar Lothbrok, Bjorn appears frequently in old Viking legends and Frankish sources — but that also makes it difficult to parse the truth about him from the mythology.
Still, the similarities from both accounts can provide a fairly well rounded description of Bjorn Ironside. He is most often described as a powerful and fearsome warrior with sides, as his name would suggest, like iron. He was known for the various expeditions he and his brothers — Ivar the Boneless, Hvitserk, and Sigurd Snake-in-the-Eye — embarked upon, particularly the Mediterranean expedition during the late ninth century.
Their exploits have been popularized in more recent years thanks to the History Channel television series Vikings, but the show also contributes further to the blurring line between myth and fact. Most of Bjorn’s exploits were shared in the 13th-century text The Saga of Ragnar Lothbrok and the later work, The Tale of Ragnar’s Sons, which chronicles the lives of Bjorn and his brothers after their father’s death.
So, who was Bjorn Ironside, really? It’s difficult to say, but what is clear is that the chronicles of his exploits have entranced readers for centuries.
Historical Accounts And Frankish Sources About Bjorn Ironside
The first mentions of Bjorn in medieval Frankish sources are somewhat contested, but they are still worth mentioning as they offer the earliest evidence of his existence.
The Annales Bertiniani and the Chronicon Fontanellense reference a Viking chieftain named “Berno” who emerged as a formidable force in West Francia during the mid-ninth century.
In the summer of 855, Berno, alongside another Viking leader named Sigtrygg, sailed up the Seine River, launching raids into the Frankish heartland. Their combined forces faced King Charles the Bald in Champagne that same year. Although they suffered a defeat, it wasn’t decisive.

Public DomainRagnar Lothbrok with his wife Aslaug, the mother of Bjorn Ironside.
Sigtrygg withdrew in 856, but Berno fortified his position, receiving reinforcements and establishing a stronghold on the island of Oissel near Rouen. From this base, they launched a significant assault on Paris around the turn of 856 and 857.
King Charles attempted to besiege Oissel in 858, but the Vikings’ robust defense, combined with political distractions from Louis the German’s invasion, forced him to abandon the effort.
After a meeting with Charles in Verberie in 858, Berno’s name disappears from contemporary records, but Viking activity along the Seine persisted, meaning he very well could have been involved.
However, another important historical text, the 13th-cenutry Gesta Danorum (“The Danish History”) by the Danish historian Saxo Grammaticus, speaks in greater detail about Bjorn and his family — including mention that Bjorn Ironside even became a legendary king of Sweden.
Chronicles Of Bjorn Ironside From The Gesta Danorum
In the Gesta Danorum, Grammaticus describes a conflict between Ragnar Lothbrok and Sörle, a newly appointed ruler of the Swedes. To resolve their dispute, both parties agreed to a combat involving select champions.
Ragnar, accompanied by his sons Bjorn, Fridleif, and Radbard, faced the renowned warrior Starkad and his seven sons.
“Bjorn, 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),” Grammaticus wrote. “This victory emboldened Ragnar to hope that he could overcome any peril, and he attacked and slew Sörle with the entire forces he was leading. He presented Bjorn with the lordship of Sweden for his conspicuous bravery and service.”

Public DomainRagnar Lothbrok’s sons meeting with King Ælla’s messengers.
Later, another of Ragnar’s sons, Ubbe, conspires with his maternal grandfather, Esbjörn, against Ragnar, while envoys are sent to Bjorn in Sweden to solicit support for their rebellion.
However, Bjorn rejects their proposal. Ever loyal to his father, he also executes the envoys and orders the slaughter of their entourage. Subsequently, Esbjörn is killed in a sea battle, and Ubbe is taken captive.
As Ragnar’s life progresses, he appoints Bjorn as the regent of Norway, while another son, Eric Weatherhat, is given control over Sweden.
After Ragnar’s death, Bjorn and his brothers launch an assault on King Ælla in England with a fleet of 400 ships in retaliation. The conflict ended with King Ælla’s death by way of blood eagle — a method of torture and execution typically believed to be fictitious.
“Meanwhile, Sigurd and Bjorn came up with a fleet of 400 ships, and with open challenge declared war against the king,” Grammaticus’ chronicle continues. “This they did at the appointed time; and when they had captured him, they ordered the figure of an eagle to be cut in his back, rejoicing to crush their most ruthless foe by marking him with the cruelest of birds. Not satisfied with imprinting a wound on him, they salted the mangled flesh. Thus Ælla was done to death, and Bjorn and Sigurd went back to their own kingdoms.”

Yolanda Perera Sánchez/Alamy Stock PhotoThe death of Ragnar Lothbrok after being thrown into a snake pit.
Bjorn then returns to his Swedish kingdom but later intervenes in Denmark to suppress another rebellion against Ragnar’s lineage. Leading a formidable fleet of 1,700 ships, Bjorn and his brothers decisively defeat the insurgents at Slesvig.
This is the last mention of Bjorn Ironside in the Gesta Danorum. It’s worth noting, however, that Grammaticus wrote his account several centuries after the subject of his tale walked the Earth — and that much of what he wrote aligns with accounts found in The Saga of Ragnar Lothbrok and The Tale of Ragnar’s Sons, though certain details, like the name of Bjorn’s mother, differ.
The trouble is that the sagas are more widely believed to be fiction, based on warriors from the ninth century. These similarities, then, also cast some doubt on the accuracy of Grammaticus’ account.
The Sagas Of Ragnar Lothbrok And The Tale Of Ragnar’s Sons

Wikimedia CommonsThe Saga of Ragnar Lothbrok.
In The Saga of Ragnar Lothbrok, Bjorn is portrayed as one of the sons of Ragnar and Aslaug — not Thora, as she is known in the Gesta — alongside his brothers Ivar the Boneless, Hvitserk, and Sigurd Snake-in-the-Eye.
The saga tells of their collective quest to expand their kingdom, including the conquest of territories like Zealand, Jutland, Gotland, and Öland. Following these conquests, they establish their stronghold in Lejre, Denmark, with Ivar assuming leadership.
It also tells of Ragnar’s ill-fated expedition to England, during which he boasted that he could invade the country with just two ships. This hubris results in his capture and death via snake pit at the hands of King Ælla.
The Tale of Ragnar’s Sons effectively picks up there, expanding, as the title suggests, on the further exploits of Ragnar’s children following his death.
Like in the Gesta, Bjorn and his brothers launch an initial assault against Ælla but face setbacks. Ivar, ever the strategist, negotiates for land, which he cleverly uses to establish a foothold. This strategic move paves the way for a renewed attack, during which they capture Ælla and exact vengeance through the blood eagle.
Bjorn and his brothers then embark on extensive raids across England, Normandy, France, and Lombardy, eventually leading them to the city of Luni, the furthest they manage to reach. Realizing it would be too difficult to take the city, especially with Rome nearby, they return to Scandinavia, where they divide their father’s kingdom and Bjorn receives Uppsala in central Sweden, as well as its surrounding lands.

Wikimedia CommonsThe barrow of Bjorn Ironside.
Once again, Bjorn disappears from the record, with no further mention of his exploits or his death. Mention of him also appears in another work from the 11th century by William of Jumièges.
This chronicle, the Gesta Normannorum Ducum (“Deeds of the Norman Dukes”) tells of Bjorn Ironside’s exploits in the Mediterranean, and also links him with another Viking named Hásteinn, who some scholars suggest may have been written out of history, his tale combined with Bjorn’s. However, the account of William of Jumièges has been widely criticized as being unreliable.
The only other noteworthy chronicle of Bjorn Ironside’s life is, frankly, the Vikings television show — so how does it compare to other accounts?
How Accurate Is The Portrayal Of Bjorn Ironside In Vikings?

History ChannelAlexander Ludwig and Katheryn Winnick as Bjorn and Lagertha in Vikings.
As far as Vikings is concerned, historical accuracy is not a priority. While many elements of the show — like costuming, for example — do capture a fairly accurate portrayal of the Viking Age, certain elements of its timeline regarding characters is entirely different.
The first major inconsistency with historical texts is, oddly once again, the name of Bjorn’s mother. In the show, she is known as Lagertha.
The series also condenses timelines, attributing various exploits to Bjorn that span different periods. For instance, his Mediterranean expedition is depicted alongside events that, historically/mythologically, occurred separately.
And naturally, given that it is a television drama, much of Bjorn’s growth as a character is entirely fabricated. Based on any historical accounts/legends, it would effectively be possible to understand Bjorn’s psychology — and the idea of a “character arc” itself is pretty much exclusive to fiction.
Still, to be fair to the show, the actual history is also rather elusive.
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