Meet the mysterious leaders of the Vikings’ most fearsome army

When the Great Heathen Army arrived in England in the mid-9th century, it marked a turning point in the history of Viking activity in the British Isles.

Earlier Viking raids – such as the attack on the monastery at Lindisfarne in 793 – had been fast, opportunistic strikes.

Viking aggression had continued like this for decades: plundering coastal regions for wealth, treasure, and people to enslave. Indeed, the Anglo-Saxons had grown accustomed to this style of attack from their Norse cousins from across the sea.

That changed in the year 865, with the arrival of the Great Heathen Army.

From then onwards, this force campaigned across Anglo-Saxon England, capturing kingdoms, overthrowing rulers and establishing long-term settlements. At the time, England didn’t even exist: Britain was a patchwork of rival states – including Northumbria, Mercia, East Anglia and Wessex – often competing with one another as much as resisting external threats. This political fragmentation made coordinated defence difficult.

The Great Heathen Army was able to make much headway: plundering, pillaging and – crucially – taking formerly Anglo-Saxon land, rather than heading back to Scandinavia.

But while the label ‘Great Heathen Army’ captures two essential facts about this force of Viking invaders – its size, and its paganism – it might otherwise be misleading.

Rather than a unified force under a single commander, the Great Heathen Army was a shifting alliance of warbands drawn together for a shared purpose but operating with considerable independence.

It was a force with many leaders – not one.

How big was the Great Heathen Army?

Contemporary sources, such as the Anglo-Saxon Chronicle, offer only limited detail as to the size of the Great Heathen Army.

Modern historians have attempted to reconstruct its scale using a combination of textual and archaeological evidence.

“Some historians have thought it’s around a hundred ships,” explains Dr Eleanor Barraclough, an expert on the history of the Viking Age, speaking on the HistoryExtra podcast. A hundred ships, she says, could translate to “two or three thousand armed warriors.”

By later medieval standards, that might not seem overwhelming. But in the context of 9th-century warfare, it represented a substantial and highly mobile force – especially one capable of moving quickly along rivers and coastlines by use of its ships.

These boats – the infamous Viking longships – were shallow-drafted vessels that could travel both across open sea and far inland via river systems, allowing Viking forces to strike deep into territory with little warning.

Where did these Vikings come from?

While many members of the Great Heathen Army did originate from regions such as Denmark and Norway, Barraclough explains that “they’re not only coming across from Scandinavia, although lots of them certainly are.” By the mid-9th century, she says, Viking raiding, trading and settlement had created networks that extended well beyond Scandinavia itself.

Viking groups had established bases in Ireland, particularly at Dublin, and were active along the coasts of Francia (modern France), the Low Countries and even as far as the Iberian Peninsula. These networks allowed people, goods and information to circulate widely.

“We have to remember that this doesn’t come out of nowhere,” Barraclough explains. There had already been “a history of these protracted raids on the continent” and along the coasts of the British Isles.

“So it’s quite possible that some of the people who are coming over are also coming, for example, from the Low Countries, from what we would call northern France, like Francia,” she notes.

The Great Heathen Army, then, was not just Scandinavian. It was a product of a wider Viking world, drawing in fighters from multiple regions connected by mobility and shared experience.

Leadership at sea

In such a diverse group of warbands, how would leadership have functioned? To answer that question, Barraclough points toward the smallest unit of fighters: the ship.

“There’ll be a leader on each of those ships,” she says. “We see that from ship burials,” Barraclough notes, citing the Salme ship burials in Estonia from around the year 750. These burials, associated with a group that had travelled from Sweden, reveal distinctions in status among those buried.

“You can tell who the leader is because of how he’s buried, the weapons he’s buried with,” she explains. In one case, the presence of a gaming piece from the board game Hnefatafl placed in the mouth of the deceased may have symbolised command or authority.

Scaling up from individual ships to an army composed of many warbands introduces more complexity.

Nevertheless, “when you’re dealing with multiple warbands, you have to have some overall leadership,” Barraclough says.

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The Anglo-Saxon Chronicle and later traditions provide names for some of these leaders. Among the most prominent are Ivar the Boneless, Halfdan Ragnarsson, and Björn Ironside .

“Tradition says that these leaders are the sons of Ragnar Lothbrok,” Barraclough explains – a semi-legendary Viking figure whose historical existence remains debated.

Guthrum, who would later become king in parts of England after converting to Christianity, was another key leader in the later stages of the conflict.

“So, there are identified leaders,” Barraclough says. “But each ship would also have had its own leader. It’s complicated.”

This layered structure meant that leadership was simultaneously centralised and decentralised. One way to think about it is that the Great Heathen Army was led by many generals, with many lieutenants, but no overall commander-in-chief.

A flexible Viking war machine

This system of overlapping leadership had practical advantages.

“From the Viking point of view, it works well,” Barraclough explains, “because it means they can be more reactive and get ahead of the Anglo-Saxons easily.”

Unlike the more rigid political structures of the Anglo-Saxon kingdoms – which were highly stratified and organised around defined territories and royal authority – the Viking coalition could divide and recombine as needed.

Anglo-Saxon militias, known as fyrds, were typically raised on a temporary basis from local populations and couldn’t remain mobilised indefinitely. This made it harder to respond to a fast-moving, professional raiding force, which had “different groups splitting in different directions at various points over the decade or so to come,” Barraclough says.

This ability to fragment into smaller units and then regroup gave the army a strategic flexibility that its opponents struggled to match. It’s partly this fluid leadership that made the Great Heathen Army such a distinct threat to the Anglo-Saxon kingdoms.

By the late 9th century, large parts of eastern and northern England had come under Viking control, an area later known as the Danelaw, where Scandinavian laws and customs held sway. If their goal was to take land, rather than just plunder it, this was a success for the Vikings.

Eleanor Barraclough was speaking to James Osborne on the HistoryExtra podcast. Listen to the full conversation.