When Did the Anglo-Saxon Invasion of Britain Really Begin?

The arrival of the Anglo-Saxons has traditionally been dated to about 449, but is this really what the earliest and best evidence suggests?

Dec 8, 2023By Caleb Howells, BA Doctrines and Methodology of Education

when was the anglo saxon invasion


The Anglo-Saxon invasion of Britain was one of the most significant events in all of British history. If the Anglo-Saxons had never come to dominate the island, then the entire course of its history would have looked extremely different. Therefore, the year in which the Anglo-Saxons first arrived should definitely be considered an important year — a turning point in British history, in fact.


So, when did they arrive? The date of this event (known as the Adventus Saxonum) is usually given as 449. This precise date comes from Bede, an English historian of the eighth century. We will see that there is evidence which suggests that the Anglo-Saxon invasion started earlier than this.


How Did the Anglo-Saxon Invasion Occur?

aetius illustration
Portrait of Flavius Aetius, by Julio Sprozza, 18th century, via British Museum


Before we look at the issue of when it happened, we first need to understand what happened. From the first century CE onwards, the Romans dominated Britain. Then in 383, the usurper Magnus Maximus took a huge portion of the Roman troops from Britain to the continent.


In 407, the usurper Constantine III seems to have done the same thing with most, if not all, of the remaining troops. In 409, the Britons expelled the Roman administration, putting an end to Roman Britain once and for all. In the years that followed, according to Gildas, the Britons struggled to defend themselves from attacks by the Picts and the Scots. They appealed to the Romans for help, but no help arrived. According to Gildas, the appeal was to a Roman named “Agitus,” whom he refers to as “thrice consul.” This has almost universally been taken as a reference to Flavius Aetius after his third consulship in 446.

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vortigen anglo saxons illustration
The first meeting of the British king Vortigern with the two Saxon Chiefs Hengist and Horsa, in the Isle of Thanet, by William Walker, 1786, British Museum, London


However, despite the appeal from the Britons, the Romans did not send any help. Therefore, with the situation increasingly desperate, the Britons hired the Anglo-Saxons to serve as mercenaries. The decision to do so is attributed by Gildas to an unnamed “unfortunate tyrant.” Later tradition gives him the name “Vortigern” (which some argue was really a title meaning “Overlord”). In exchange for their service as mercenaries, the Anglo-Saxons were given some land in the south east of the country.


sutton hoo helmet anglo saxon
Sutton Hoo helmet, seventh century, British Museum


However, over time, they demanded more resources. The Britons refused to comply, so the Anglo-Saxons became dissatisfied with their arrangement. They broke their deal with the Britons and began taking more land and resources by force. Thus began the Anglo-Saxon conquest of Britain. It was not an “invasion” as such, but rather, a conquest that spread out from territory that the Anglo-Saxons had already received amicably. Nonetheless, once this conquest began, the Anglo-Saxons started bringing more and more of their countrymen over from the Germanic territories on the continent.


Where Does the Traditional Date Come From?

venerable bede ecclesiastical history english people
Folio of Tiberius Bede, manuscript of Bede’s Ecclesiastical History, eighth century, via the British Library


Now that we know what the documentary evidence tells us, we can start to see where the traditional date comes from. We know that the Britons only appealed to the Germanic mercenaries because the Romans had left them defenceless. That means that we must be looking at a date after 407. However, the real key to the dating issue — the key which led Bede to propose the year 449 — is Gildas’ reference to the appeal to Agitus. One of the only known historical figures from that time period whose name can definitely be connected to “Agitus” on philological grounds is Flavius Aetius. He was a powerful general and statesman active in the collapsing Western Roman Empire in the fifth century.


Furthermore, he is one of the only figures from the fifth century who was consul at least three times. This would appear to match Gildas’ reference to Agitus as “thrice consul.” Since the third consulship of Aetius was in 446, the Britons’ appeal to him could only have come after that year. We also know that Aetius died in 454, further limiting when this appeal could have been sent. It is essentially from this information that Bede chose his date of about 449 for the Aventus Saxonum.


Is Gildas Really the Earliest Evidence?

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Statue of Saint Gildas, Morbihan, France, via Worldhistory.org


As we can see, the traditional date of 449 ultimately comes from Gildas. It is his reference to the appeal to Agitus that has come to define the entire chronology. Since Gildas was the earliest writer to describe the events leading up to the Anglo-Saxon invasion, this might seem logical. But is Gildas really the earliest source that we have for these events? It is true that no surviving source from before him describes the events leading up to the invasion. However, there are earlier sources that make reference to the Anglo-Saxon invasion itself.


One key source is the Life of St Germanus, written by Constantius of Lyon in around 480. This is significantly earlier than when Gildas composed his De Excidio, far into the sixth century. But even more valuable still is the Gallic Chronicle of 452. As shown by the title, this chronicle was composed even earlier than the Life of St Germanus. Neither of these two sources comes from Britain, but they do refer to events happening there.


The Life of St Germanus

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Depiction of Saint Germanus of Auxerre, 2019, via Aidanharticons.com


The Life of St Germanus, written by Constantius of Lyon in c. 480, describes the activities of Germanus of Auxerre. He was a prominent religious figure who was sent to Britain to deal with the heresy of Pelasgianism that had become popular there. In fact, he was sent to Britain on two separate occasions, according to this source. The first was in about 430, and the second was in 447.


During the first mission, an event took place known as the Alleluia Victory. This was a victory for the Britons over a joint army of Picts and Saxons. Supposedly, Germanus led the Britons to victory by having them shout “Alleluia” (meaning “Praise Jehovah”). This allegedly frightened off the attacking army.


Why is this so significant? Well, according to this account, written just fifty years after the events it describes, there was already warfare between the Britons and the Saxons as early as 430. This is clearly inconsistent with the traditional date of 449 for the Adventus Saxonum.


The Gallic Chronicle of 452

sutton hoo sword
Sutton Hoo sword, seventh century, British Museum


Perhaps the aforementioned evidence could be dismissed as merely referring to a passing raid by the Saxons. After all, the Gallic Chronicle of 452 mentions a Saxon raid on Britain as early as 409, which was clearly separate to the actual Saxon conquest of the fifth century. However, there is even stronger evidence that the Anglo-Saxon invasion really did start much earlier than 449. In the Gallic Chronicle of 452, in the entry for the year 441, we find this statement:


“The British provinces, having up to this time suffered various defeats and calamities, were widely reduced to Saxon rule.” 


This is a definitive, contemporary statement to the effect that the Anglo-Saxon conquest was well underway by the year 441. Given the date of the composition of this chronicle, it is untenable that this date is out by more than one or two years. The date of 449 for the Adventus Saxonum is simply not possible in view of this evidence.


That is not to say that almost all of Britain really was reduced to Saxon rule by the year 441. But what this shows is that the Saxons must have conquered enough of Britain for it to have seemed like that to a writer on the continent.


What the Archaeology Reveals

anglo saxon urn
Anglo-Saxon urn, fifth century, via British Museum, London


Aside from contemporary literary evidence, we also have another type of contemporary evidence – archaeological remains. These archaeological remains clearly favor the early date. It is acknowledged by the most recent writers on the topic that the archaeological evidence clearly points to a strong Saxon presence in Britain as early as about 430. Historian Marc Morris explained that from 430 onwards, we find in Britain “burials, artefacts and buildings of a kind that were utterly unfamiliar in late Roman Britain, but entirely commonplace in northern Germany and southern Scandinavia.”


Examples include the practice of cremation and the inclusion of grave goods in the burials of non-cremated individuals. The specific designs of the grave goods are also paralleled by similar finds in Germany and Scandinavia, but not in late Roman Britain. Therefore, what this evidence demonstrates is that the Anglo-Saxons arrived (and in large enough numbers to leave a clear archaeological trace) in about 430. This is some twenty years earlier than the traditional date.


So When Did The Anglo-Saxon Invasions Occur?

screaming anglo saxon reenactors
Re-enactment group as Anglo-Saxon warriors, via hampshireattractions.com


In conclusion, we can see that the traditional date of 449 for the arrival of the Anglo-Saxons is derived from the words of Gildas. His De Excidio contained the information about the appeal to “Agitus, thrice consul,” which led to Bede choosing his date of 449 for the Adventus Saxonum. However, evidence from earlier sources contradicts this. The Life of St Germanus, written in c. 480, shows that the Britons were fighting Saxons in Britain in approximately 430. The Gallic Chronicle of 452 states that Britain had already largely fallen under Saxon control by 441. This is consistent with the idea that the Anglo-Saxons were already waging war against the Britons by 430. The archaeological evidence, too, shows that the Anglo-Saxons had arrived by about that year. In fact, we even see this same date in later literary traditions. The Historia Brittonum, written in c. 830, claims that the Anglo-Saxons arrived in 428.


The sum of all the evidence is that Gildas’ reference to Agitus is clearly the outlier. It certainly should not be used to define the entire chronology. The weight of evidence indicates that the Anglo-Saxons arrived in or shortly before 430, not 449.

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By Caleb HowellsBA Doctrines and Methodology of EducationCaleb is a published history author with a strong interest in ancient Britain and the Mediterranean world. He holds a BA in the Doctrines and Methodology of Education from USILACS. He is the author of "King Arthur: The Man Who Conquered Europe" and "The Trojan Kings of Britain: Myth or History?". Caleb enjoys learning about history in general, but he especially loves investigating myths and legends and seeing how they might be explained by historical events and individuals.