How Ivar the Boneless Became a Feared Warlord and Beloved King

History's "Vikings" shifted its focus in the second half of season 5 from the legendary viking warrior, Ragnar Lothbrok, to his sons, Björn Ironside and Ivar the Boneless.

While previous installments of the show took plenty of creative liberties in order to craft a coherent story of the sparsely documented early days of the Viking Age, the lives of Björn and Ivar are more thoroughly recorded, which means this season is likely to be rooted in hard evidence.

In real life, Björn "Ironside" Ragnarsson was a legendary king of Sweden and founder of the Munsö dynasty. He brought tremendous prosperity to his people by leading vicious raids and establishing bountiful trade routes across the Old World. Ivar "the Boneless" Ragnarsson, on the other hand, is remembered as either being a masterful, yet slightly psychotic general of the Great Heathen Army or as the revered founder of Dublin -- sometimes both.

Since most historical accounts are steeped in myth and lore, it's hard to pin down what kind of man Ivar was, exactly, but the stories are fascinating nonetheless.

Upon first hearing his name, you're bound to wonder how he came to be known as "the Boneless" -- there are several theories. Some historians believe he suffered from osteogenesis imperfecta, otherwise known as "brittle bone disease," a genetic disorder that causes the person's bones to be, as the name implies, extremely brittle, which was a less-than-desirable affliction to have during in the Viking Age.

This theory is reinforced by accounts from the Great Heathen Army's siege of Northumbria, during which, according to both English sources and Norse legends, he was carried atop a shield. This gave the English "proof" that he couldn't walk on his own -- a trait common among those with osteogenesis imperfecta. It's important to note, however, that other sources of this period say that a Viking victoriously riding on the shields of their enemies was the equivalent of sending a ceremonial middle finger to the losing side.

There's also speculation that, since he never fathered any children, the name may have been in reference to him being impotent. Though there's no conclusive proof of this, Vikings were known for giving each other crude nicknames of that ilk.

Finally, a third theory stems from poems describing his agility in battle. The poems said he was a fluid fighter, like a snake on the hunt. "The Boneless" would then imply that he fought as if he had no bones, dodging around swings of swords and axes with ease.

It's hard to say now which of these theories is most true, but it's important to recognize that they're not necessarily mutually exclusive — as is shown in the television series.

Though the evidence isn't conclusive that he lived with brittle bone disease, there's enough evidence to assume. Legend has it that his mother, Aslaug, was a shaman who foretold that if she and her husband, Ragnar, were to consummate their marriage within three days of his return from a siege, their child would be cursed. Overcome with lust, Ragnar didn't heed her warning.

In actuality, osteogenesis imperfecta is extremely rare; fewer than 20,000 cases occur in the United States annually. Patients with most severe cases of OI, unfortunately, don't typically make it past infancy, even with modern medicine. Living with Type 1 OI, the most common and most mild type of OI, is understandably difficult, but it's not a death sentence -- even during the Viking Age.

Any Viking with Type 1 OI, like Ivar, would not be suited for the shield wall or disembarking from ships to raid monasteries. Instead, as all legends, tales and historical accounts of Ivar say, he would stay in the back and strategize from a location that wouldn't put his body in jeopardy.

Adults with Type 1 OI are encouraged to maintain a healthy, low weight/high repetition workout routine. Higher weights can cause fractures in the bones that take years to heal, but toning muscles with lower-impact exercises helps fortify the bones. These same low-weight/high-rep workout routines also result in a leaner and more agile body type, just as Ivar was described in the poem, "Hattalykill."

Additionally, one of the best treatments for brittle bone disease is a high-calcium diet. Luckily for Ivar, the typical Danish diet is one of the highest in calcium in the world. Once you factor in all of these, the likelihood of Ivar managing to be a deadly fighter with Type 1 OI is far more plausible.

Ivar the Boneless was a complicated character, both in reality and in fiction. Ivar was painted as the villain by Christians of Old England and loathed by other Vikings when he left for Ireland. In Ireland, he was a beloved leader known as Imar the King of the Norsemen of all Ireland and Britain.

Again, much has been lost to time, but there's a lot of evidence that suggests Ivar and Imar are the same person. Both were Norsemen, both were said to rule in Dublin around the same time, and both were said to have been killed around the same time. There are even periods of time in which Imar isn't mentioned in the "Fragmentary Annals of Ireland" that line up perfectly with Ivar's return to Denmark. The peculiar thing is that Imar was never said to have brittle bones -- and he fathered three children who carried on the Uí Ímair dynasty.

The series actor who portrays Ivar, Alex Høgh Andersen, explained in an interview with the New York Post, "He is an antihero with emphasis on 'anti.' It's interesting to have a character who is becoming the lead character and yet he's almost the villain."

Since campfire tales and second-hand accounts written well after a person's death can skew a person's story, it's hard to accurately describe Ivar as a leader. Imar was said to have been deeply loved by his people, but Ivar was depicted as a monster by his enemies -- but one man can certainly be both.

More posts from We Are the Mighty:

Why Sweden is low-key one of the greatest superpowers

How this 20th century viking fought in 13 wars around the world

Why the real Ragnar Lothbrok is so shrouded in mystery

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