While Viking incursions onto the British Isles began in 789 CE, these were little more than opportunistic raids to plunder and pillage coastal communities. 

Yet in 865 CE, a huge Viking force (believed to be over 3,000 men) landed on the Isle of Thanet in modern-day Kent. 

Their intention was different: they wanted to subdue all the Anglo-Saxon kingdoms and to bring what the locals called "Englaland" under the Viking yoke. 

The Great Heathen Army had arrived. Their arrival would change European history forever.

Semantics and bias

Before diving into the deep end of knowledge and trying to ascertain the events surrounding the invasion of the Anglo-Saxon by hordes of Vikings, first, we must ask a simple question: what exactly is a "Great Heathen Army"? 

The name itself comes from perhaps our best source of knowledge of life in the British Isles during the early medieval period, the Anglo-Saxon Chronicle

Yet this chronicle, like all history, should be viewed with a skeptical eye. This was a recorded history written during the reign of King Alfred the Great, King of Wessex and then of all the Anglo-Saxons, sometime in the 9th century CE. 

We must remember that Alfred was the great scourge to the Vikings and, after a series of tactical military losses, would eventually win a strategic battle to keep the Vikings out of the last remaining Anglo-Saxon kingdom, Wessex. 

Given that this chronicle was written in Alfred's court, would it not then be possible that the unknown author would want to play up the size and threat of this invading Viking army?

Modern historians have cast their eyes on the use of language in the chronicle to describe this invading force. Under the invasion of the Vikings in 865 CE, the Anglo-Saxon term used here, as described in an earlier law code written in Wessex, described it as a raiding or invading party of more than 35 men. 

That hardly seems like the marauding hordes of Valhalla that one imagines with the use of the term "Great Heathen Army." The best estimates for its size, analyzing the numbers of Viking ships mentioned in the Chronicle, range somewhere between 1,000 - 3,000, in the very low thousands.

The use of the term "heathen" was, of course, to differentiate the (mainly) Vikings who (mainly) practiced the spiritual belief system stemming from the Old Norse religion. 

This use of "heathen" was used to contrast the Viking force with the "good Christian" rule of Alfred. Only "heathens" (essentially pagan barbarians) inflict some "unholy" damage in a Christian realm. Yet we cannot say for certain that ALL of the invaders were non-Christian. 

Nonetheless, labeling the invading force as "the relatively large invading force the early medieval period made up of mostly believers in the Old Norse religion" may well be historically accurate, but it doesn't quite roll off the tongue...

Centuries of invasions and raids

Semantics aside, invading forces had been, by the era of the Vikings, invading the British Isles at an increasingly alarming rate. In fact, invasions have been occurring since antiquity. 

Perhaps the most famous pre-Vikings was launched by the Roman Emperor Claudius in 43 CE. It took the might of Rome more than four decades to eventually subdue much of the British Isles, but they could never quite extend their control to Scotland or the island of Ireland.

Rome stuck around, built some roads, and did what the Romans did (historians of the past would say they brought "civilization" to the British Isles, but we now know that the human footprint in the part of the world stretches back more than 40,000 years ago so, sorry Romans, civilization was already there eons before you lot invaded...but you do build a very straight road, though). 

Still, the gradual insecurity from a series of population migrations into the Roman Empire, during the late 4th and into the early 5th century CE, saw a Roman withdrawal from the Isles. This transition saw the British Isles laid open for invasion by a series of new peoples, specifically a number of Germanic peoples ranging from the Jutes, the Angles, and the Saxons.

By the time of the first Viking invasions on the British Isles, in the late 8th century CE, the local population of the British Isles had seen centuries of raids and invasions from across the seas. 

Yet events further afield in Francia would see the initial Viking opportunistic raids turn more permanent by the mid-9th century CE.

Vikings were setting their sights on new raiding targets. Illustration: The Viking Herald

Old and new lands to raid

The current academic thinking is that much of the invading force came not from the Viking homelands in Scandinavia but from campaigns against the Frankish realms. 

Charlemagne, the Frankish ruler and later first Holy Roman Emperor, had died in 814 CE, essentially ending a period of relative security for the Frankish realms where they could, at least, do their best to beat back Viking incursions and raids. 

However, the Emperor's death sparked a dynastic power struggle that the Vikings would ruthlessly capitalize on. The following five decades saw a steady stream of Viking fleets raid across Frankish coastal communities at first and then take the many river routes to terrorize communities inland.

The most famous of these raids was the siege of Paris, in 845 CE, which was led by the semi-legendary Viking chieftain Ragnar Lothbrok. Despite paying the Vikings a huge amount of silver, the Vikings did not stay away, and in fact, this payment only encouraged further raids and incursions. 

Yet by the mid-860s CE, Frankish King Charles the Bald had somewhat secured his borders, drying up the steady revenue stream of the Vikings. Looking for new lands to plunder, the Vikings only had to gaze across the English Channel for their next target.

The invasion begins

If we turn our attention to the Norse sagas now, the traditional leaders of the invading force were said to be the three sons of Ragnar Lothbrok – Ivar the Boneless, Halfdan Ragnarsson, and Ubba. 

The sagas mention that this invasion was a direct consequence of their father's death at the hands of a King of Northumbria (one of the 6 Anglo-Saxon realms in the British Isles) but, unfortunately, this cannot be conclusively proven. 

Their father, the scourge of Paris, was said to have been captured during a Viking raid on Northumbria and thrown into a pit full of snakes – managing to curse the King and warn him that his sons would avenge his slippery death.

The invasion was said to have taken place in 865 CE, according to the Chronicle. However, recent academics have thought of this as the beginning of a series of invasions over the course of the next 14 years. 

Whilst a – for the period – relatively large force may have landed on the East Anglian coast in 865 CE, many smaller forces would also invade over the course of the next decade and a half. 865 CE, then, should be seen as the beginning of large-scale Viking invasions rather than just a singular invasion. 

Using East Anglia as the start of their invasion, the Vikings were up to their old tricks – having been given a huge sum of gold to stay away, the Vikings took it and did the opposite.

Within a year, the Vikings had not only subdued the Kingdom of East Anglia but had taken York, the capital of the Kingdom of Northumbria. York would be transformed into Jorvik – the beating center of the Viking world, on the British Isles, for more than a century. 

In fact, findings uncovered during a series of archaeological digs on Coppergate in the heart of York, less than half a century ago, have uncovered a wealth of Viking daily life. 

The Kingdom of Northumbria paid the Vikings off – the famous danegjeld (Danish payment) and they had marched south to lay siege to the capital of the Kingdom of Merica, Nottingham, right in the heart of what is now England.

The Viking force rested in York, preparing for the summer campaign. Illustration: The Viking Herald 

An uneasy peace

After the initial success of the Viking invasion, the momentum stalled. Failing to capture Nottingham in 868 CE, the Vikings did receive a large amount of gold from the Kingdom of Mercia. 

Heading north to York, in the winter of 868/9 CE, allowed them to bide their time and gather strength in numbers before the summer campaign. 

Heading south now, using the old Roman roads constructed centuries before (but still the best route for transport in England), the Vikings turned their attention to East Anglia. 

Whilst camping in Thretford, the King of East Anglia, Edmund, launched a surprise attack meant to thwart the Viking threat once and for all. Yet the attack failed, and Edmund was believed to have been captured, tortured, and killed, earning the epithet "the Matyr" for his troubles.

By 871 CE, the Vikings had been up and down all of the Anglo-Saxon realms and were in dire need of new resources and men. A new force, dubbed "The Great Summer Army," landed in East Anglia led by a Viking chieftain which the Chronicle has named Bagsecg. 

This new injection of personnel and military power saw the Vikings head south to try and defeat the Kingdom of Wessex, led by Æthelred. His young brother, Alfred, managed to inflict a resounding defeat at Ashdown against the invading warriors. 

Yet much of Anglo-Saxon England was, directly or indirectly, already controlled by the Vikings. They simply retreated north, eventually being paid off by the new King of Wessex, Alfred, to stay away.

The next year saw the Vikings winter in London and turn their attention again northward to Northumbria, squashing a popular rebellion against their rule. 

The writing was on the wall for the rest of the Anglo-Saxon kingdoms. Mercia fell in 874 CE, leaving only Wessex, led by King Alfred, alone in the fight against Viking overlordship.

The end of military campaigns, Danelaw and Alfred's great victory

By 874 CE, Viking armies had marched up and down all of England and had laid waste to the Anglo-Saxon kingdoms, communities, and lands. 

According to Asser, the man charged with writing the first biography of Alfred the Great, it was here in 874 CE that the "Great Heathen Army" divided into two. Half marched back up north to fight as far north as the Kingdom of Strathclyde in Scotland. 

Led by Halfdan, this half of the army then laid waste to Northumbria upon their return south. Soon this area was populated by people from Viking societies allowing Haldfan to establish what has been called the "Danelaw," i.e., the area of England that was under Viking rule and law.

This decision to divide the Viking force into two, according to Asser, showed the military ineptitude of the Vikings (this military "ineptitude" flies in the face of the reality that the Vikings had not only conquered 5/6 of Anglo-Saxon England but had also whipped the might of Wessex in many battles) which King Alfred would capitalize on in 878 CE at Edington. 

This battle, against a supposedly weakened Viking force (both numerically and, one wonders, possibly psychologically – they had been on campaign for more than 13 years at this point) not only provided the long-term security of Wessex but the Viking elite, including their leader Guthrum, were baptized.

The vast Viking invasions and campaigns, led by the "Great Heathen Army," were at an end following Alfred's victory at Edington. 

Yet the Anglo-Saxons would never again rule all of England again as just as they would eventually reclaim much of their lost territory, over the course of the next two centuries, a new threat would emerge from across the English Channel in the Duchy of Normandy.

Science Norway has recently published an article on what the "Great Heathen Army" brought with them over to the British Isles, available to read here

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