“Favourable winds brought the Trojan Brutus to the promised isle, which at that time was called Albion. It had no inhabitants save for a few giants. This pleasant land led Brutus and his companions to settle there and, after driving off to mountain caves any giants they encountered, they divided it up and portioned it out. Brutus named the island Britain after himself and called his followers Britons” – So the 12th-century writer Geoffrey of Monmouth described how Britain first came to be discovered, named and settled. Compiled in around 1136, Geoffrey’s Historia Regum Britanniae (History of the Kings of Britain) is an epic, which chronicles the rulers of Britain from earliest times until the seventh century AD. Containing characters such as Cole (the merry old soul), Lear and Cymbeline (both later immortalised by Shakespeare), as well as Arthur, Merlin and Mordred, the Historia was a medieval bestseller, and its influence upon European culture cannot be overstated.


Who was Geoffrey of Monmouth? We know next to nothing about Geoffrey but it would appear that he was either born or spent a significant amount of time in Monmouthshire, at the borderlands between what is now England and Wales, in the early years of the 12th century. He was certainly familiar with the geography of the area – the Roman fortress town of Caerleon, near Monmouth, appears many times in the Historia Regum Britanniae. Geoffrey spent most of his working life in Oxford, his name appearing on a number of charters there between 1129 and 1151, where he is referred to as magister or teacher. Geoffrey apparently conceived the Historia at the request of Walter, archdeacon of Oxford, in order to provide the British with their own heroic mythology: a national epic to rival any produced by the Saxons or Normans. It is thanks to his Historia that Geoffrey is widely remembered as the man who, more than any other, created and popularised the myth of King Arthur. The Historia features, for the first time, the whole life of Arthur, from his conception at Tintagel in Cornwall, his battles across Britain and Europe with his sword Caliburn (Excalibur), his love for Ganhumara (Guinevere), his colleagues Gawain and Merlin, the treachery of Mordred and the final battle after which, mortally wounded, Arthur is carried to the Isle of Avalon.

Geoffrey’s work clearly contains numerous fictional stories – and so it’s hardly surprising that, within a few years of the Historia being published, serious doubt was being cast on the authenticity of his research. In 1190 William of Newburgh declared that “it is quite clear that everything this man wrote… was made up”, while 800 years later, Geoffrey Ashe insisted that “Monmouth is an entertaining and memorable companion, so long as one never believes anything he says”.

Geoffrey himself claimed that the inspiration for his work was an ancient book “in the British tongue”. Yet the fact that this source remains utterly elusive to us today has added weight to the conviction that it was nothing more than a figment of his imagination.

However, I think this view does Geoffrey a disservice. In fact, having examined the Historia in great detail over recent months, I’m convinced that there is sufficient evidence within its pages to suggest that it was no work of make-believe. On the contrary, I believe that it was compiled from a variety of genuine sources – most of them hailing from what is now the south-east of England – dating back at least to the first century BC.

For me, the key to unlocking Geoffrey’s text lies in the story of Julius Caesar’s invasion of Britain, the first ‘event’ in the book that can be independently verified from other historical sources.

The key to unlocking Geoffrey’s text lies in the story of Julius Caesar’s invasion of Britain

Caesar stepped ashore on these islands on two separate occasions – in 55 and 54 BC – and recorded his exploits in a series of campaign diaries, known collectively as the Gallic Wars. In Caesar’s own account of his second invasion, there are three main protagonists: the hero (himself); the villain, a British king called Cassivellaunus whom Caesar defeats; and the ally, a young British aristocrat called Mandubracius.

In the Historia, however, Geoffrey duplicates the events of 54 BC, and sets them down as if they are two discrete military operations. In the first, the aggressor, Ilkassar (Caesar), is defeated by the heroic Briton Cassibellaun (Cassivellaunus) at the “Battle of Dorobellum” and driven back into the sea.

In the second version, a few pages later, Cassibellaun, now the bad guy, is waging an unprovoked war upon his rival, Androgeus (Mandubracius), when he hears that Ilkassar has landed upon the south coast. At the battle of Durobernia, Ilkassar prevails, thanks to the timely intervention of Androgeus on the Roman side. Fearing the power of Androgeus, Ilkassar makes peace and departs.

It is clear that in describing this particular invasion, Geoffrey was using two versions of the same event, written from two very different perspectives. The first, with Cassivellaunus as the hero, appears to have been generated by supporters of the British king; the second is written from the perspective of Cassivellaunus’s rival, Mandubracius.

It may therefore be wrong to search for a single primary source for Geoffrey’s account – after all, as he says in his foreword, in his day the lives of these early kings were “celebrated by many people by heart, as if they had been written”. As one might expect for a pre-Roman heroic society, these tales had survived to Geoffrey’s time not because they had been transcribed but because they had been transmitted from generation to generation by word of mouth.

Listen: Miles Russell offers a bold view on the historical King Arthur based on his reinterpretation of medieval sources, on this episode of the HistoryExtra podcast:

How reliable is Geoffrey of Monmouth’s Historia?

Once you accept that the Historia does not represent a single epic but a mass of unrelated stories woven together to form a grand narrative, it’s easier to tease out individual tales. And these tales can radically reconfigure our understanding of the British past, producing new ways of seeing how the Britons dealt with the arrival of Rome, and what happened following the collapse of Roman authority in the fifth century AD.

The Historia matters because it is something that was set down by the ancient Britons themselves: it is their ‘lost voice’. This is, perhaps, best summed up by the description of the celebrations following the expulsion of Julius Caesar from Britain.

The Britons, we are told, “summoned all the nobility” to Colchester “in order to perform solemn sacrifices to the gods”, slaughtering “40,000 cows and 100,000 sheep and also fowls of every single kind without number, besides 30,000 wild beasts of several kinds” before “they feasted themselves… and spent the rest of the day and night in various plays and sports”.

This is no work of pure fiction but the remembrance of a real event from a period of the past we still mistakenly call prehistory.

8 insights that the Historia can give us into ancient Britain

1 Ancient Britons gloried in their Trojan ‘past’

Perhaps the most incredible claim contained within the pages of the Historia is that the British monarchy was descended from Trojan nobility. As far-fetched as this may seem, a chance comment by John Creighton in his book Coins and Power in Late Iron Age Britain (published in 2000) suggests that Geoffrey didn’t merely pluck this ‘fact’ from the ether.

Creighton noted that it “exemplifies precisely the genre of foundation myth that would have been created within the political context of Britain” in the early first century AD. In other words, British dynasts of late Iron Age Britain may have wanted to fabricate a semi-mythical lineage that closely linked them to the Romans, who themselves claimed descent from the Trojan refugee Aeneas. (The Britons were also, remember, keen to adopt Roman symbols and titles on their coins.)

This is something that Geoffrey has Julius Caesar himself articulate when, just prior to the invasion of Britain, he observes that “we Romans and the Britons share a common ancestry”.





2 Young British aristocrats were educated in Rome

Geoffrey says that many British kings travelled to, and grew up in, Rome. On the face of it, this seems preposterous, but the system of bringing up the children of allied kings in the imperial capital was an old and established one. Such children may have gone to Rome partly in order to ensure the loyalty of their parents, but also to be educated the Roman way and benefit from imperial patronage – a system of networking that proved vital to those determined to make it big.

Having the offspring of barbarian aristocrats growing up under close supervision in Rome is something that emperors such as Augustus positively encouraged, and it is difficult to see why the Britons would have been treated differently. A number of British kings are known to have been at court during the reigns of both Augustus and Claudius, while images reproduced on early British coins slavishly imitated Roman designs, confirming a strong Mediterranean influence.





3 Tenvantius fathered the ‘Great King of the Britons’

One of the many British kings that Geoffrey describes in the Historia is Tenvantius, Duke of Cornwall, a warlike man who, we’re told, “governed his realm diligently”, insisting on “the full rigour of the law”. Unfortunately, Tenvantius is conspicuous by his absence from the Roman sources – yet that doesn’t mean he’s a figment of Geoffrey’s imagination.

As Geoffrey tells us, after Tenvantius’s death the crown passed to his son Cymbeline (or Cunobelinos), who is recorded on coins and in contemporary historical accounts, as ‘Great King of the Britons’.

Interestingly, on Cymbeline’s coin series – minted from native power centres at both Colchester and St Albans – the monarch declares that his father had been ‘Tasciovanus’. It is clear from these coins, and those minted by Tasciovanus himself, that Tenvantius/Tasciovanus was very real – his name, like that of Cymbeline/Cunobelinos, being irrevocably garbled over time.





4 Britons helped quell Boudica’s rebellion

That the Historia was compiled from sources produced within the pro-Roman tribal kingdoms of south-eastern Britain is confirmed by the fact that those who fought against Rome, such as Caratacus or Boudica, barely merit a mention. And when they do, it’s hardly in glowing terms – Geoffrey casts the Boudican revolt of AD 60–61 as a wholly negative event.

Boudica herself appears as ‘Soderick’, while her tribe, the Iceni, are called ‘Scythians’. Geoffrey also gets his geography mixed up, moving the revolt from Norfolk to southern Scotland. Crucially, when the Iceni/Scythians start razing the region, it is not the Romans who march to attack them but the British king ‘Marius’, who “won several engagements and killed Soderick”.

In the Roman account there is no room for native allies. Yet the fact that the southern British kingdoms thrived in the revolt’s aftermath suggests that the Romans received significant support from indigenous groups.





5 There was method to the geographical madness

Geoffrey’s detractors have long used his appreciation of geography – or lack of it – as a stick with which to beat him. Not only, they point out, did he mistakenly claim that Boudica went on the rampage across southern Scotland, he also moved various towns, cities and battlefields from their rightful historical settings of Kent, Hertfordshire and Essex a hundred miles or so west to Wales and Cornwall.

Yet I believe that, far from simply sticking a pin in a map, Geoffrey genuinely based the settings of his history on Roman sources – it’s just that, on a number of notable occasions, he misinterpreted these sources.

Take the titles the ‘Duke of Cornwall’ and the ‘Duke of London’, both of which repeatedly crop up in the Historia. It seems that Geoffrey mistook ‘Catuvellauni’ for ‘Kerniw’ – or Cornwall – when in fact Catuvellauni was the name of a British tribe based around St Albans. Likewise, he took Trinovantes to mean ‘New Troy’ or ‘London’, when it referred to another British tribe, this one established around Colchester.

By AD 1136, both tribal names had lost any meaning and so Geoffrey equated them with geographical terms that made sense to his audience.





6 British grandees built big in southern England

According to Geoffrey, mid-first-century AD Britain was ruled by King Coilus, who “had been brought up from his infancy in Rome”. By paying what was required to the Roman government, Coilus “enjoyed his kingdom in peace and no king ever showed greater respect to his nobility… binding them to him through his continual bounty and munificence”.

There can be little doubt that of all the areas of early Roman Britain, the most bountiful and munificent was along the coast of central southern England. Here, the remains of at least eight palaces, of which Fishbourne is the most famous, have been found.

That extravagant new residences were being erected by native aristocrats such as Togidubnus, Catuarus and Lucullus is beyond doubt – the last of these could plausibly have been Geoffrey’s peace-loving ‘Coilus’.





7 The Romans may have added their own touches to Stonehenge

One of the most curious incidents in the Historia relates to Stonehenge which, we are told, was set up by the post-Roman King ‘Aurelius Ambrosius’ to commemorate those treacherously slaughtered by the Saxons. The stones in question were, on advice from the wizard Merlin, taken from a mountain in Ireland and transported to Salisbury Plain.

This story may read like it’s straight out of a fairy tale, yet it could be doing Geoffrey a disservice to dismiss it as a mere flight of fancy. For a start, we know that the bluestones at Stonehenge did indeed originate from a source in the west – albeit Pembrokeshire in Wales rather than Ireland.

What’s more, recent excavations at the monument hint at significant late or post Roman activity. Many of the bluestones that we see at Stonehenge today may actually have been reshaped, reset or otherwise significantly modified in the fourth or early fifth century AD, during the time that the historical Ambrosius Aurelianus is thought to have ruled.





8 A native elite ran south-east Roman Britain

The Historia presents an alternative late Iron Age Britain in which there is no military occupation by a foreign power. Rather than being part of a Roman province, Geoffrey describes Britain as a friendly, tribute-paying dependency whose monarchs retained a degree of autonomy beyond Rome’s invasion of AD 43.

At first glance, this may appear to be a hopelessly rose-tinted interpretation of the facts. But is it? After all, having invaded south-east England – the area from which most of Geoffrey’s sources hailed – the Roman army swiftly moved on to fight the recalcitrant tribes to the north and west. And, instead of leaving garrisons, they delegated day-to-day governance of the area to the native elite.

So, as far as the south-eastern corner of the island was concerned, Geoffrey was right: the transition from Britain to Roman Britain would have appeared relatively seamless.

Miles Russell is a senior lecturer in archaeology at Bournemouth University. He is co-author of UnRoman Britain: Exposing the Myth of Britannia (The History Press, 2011).


This article was first published in the December 2014 issue of BBC History Magazine