This article was first published in the June 2016 issue of BBC History Magazine


Anyone with a scintilla of interest in Roman history knows the story. While the Roman empire was at its height, Britain was a murky, barbaric backwater – an insignificant rain-soaked outpost shivering on the edge of the known world. But in the late third century AD, at least, this well-worn cliche couldn’t have been further from the truth. For, in the 280s and 290s, two men – the brilliant tactician Carausius, and his ruthless successor, Allectus – propelled Britain to the centre of world events. Not only did they lead a breakaway empire from their power base in Britannia, they challenged the very authority of Rome itself.

Carausius and Allectus’s story, inasmuch as we can reconstruct it, began when a succession of military rulers reunited a declining Roman empire following a period of political turmoil, only for their short reigns to end in their overthrow and assassination. When, in AD 285, the emperor Carinus was defeated in battle by his rival Diocletian in a river valley in the Balkans, it seemed as if the weary process of rebellion and overthrow would continue indefinitely.

To remain master of the Roman world the victorious Diocletian would need a novel solution to the empire’s ills. Fortunately Diocletian was an energetic reformer. He decided that a deputy ruler was needed to help deal with the rebellions and barbarian invasions facing him and, having no sons of his own, he appointed his old comrade-in-arms, Maximian.

Maximian was sent west, to Gaul, where a peasants’ revolt had turned into open war, with cities being ransacked and burned. But the figure who shone most brightly in this war was not Maximian. It was another commander, a man of humble birth called Marcus Aurelius Mausaeus Carausius, who was a native of Menapia, an area corresponding roughly with modern Belgium. Impressed by his skills, Maximian gave Carausius command of the Roman fleet in the Channel and ordered him to clear the sea of Germanic pirates who were plundering coastal settlements. Maximian then departed to wage war against the Germans on the Rhine, and left Carausius to his own devices.

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Carausius’s campaign against the pirates was highly effective, but somehow he fell out of favour with his superior. In AD 286 word reached Maximian that Carausius was keeping for himself the plunder taken from the pirates, rather than restoring it to its rightful owners. We’ll never know if there was any truth to the accusation but the emperor believed it and ordered that Carausius be put to death. Carausius defiantly proclaimed himself emperor in opposition to Maximian and sailed for Britain.

By commandeering Rome’s northern fleet and seizing the island of Britain, Carausius placed himself in a strong position. Without ships Maximian could not launch an invasion immediately, and this allowed Carausius to build up his defences. Britain also had three legions, and this combination of ground and naval forces made him a formidable power.

How Carausius established his rule over Britain is lost to us. He may have nurtured links before his usurpation, and it is possible that he had campaigned there in recent years, forging relations with leading figures and the legionary commanders.

Local support would help to explain why Carausius’s breakaway British empire was so successful. We can see that his authority extended throughout the province, for at Carlisle on Hadrian’s Wall a milestone was erected in his name, and his coins are found widely throughout Roman Britain. Excavations at Roman strongholds along the southern and eastern coast of Britain, such as Portchester Castle in Hampshire, have revealed that Carausius had a hand in either building or strengthening these structures.

European conquest

Carausius also managed to attract others to his cause. After suppressing piracy in the Channel he was popular with merchants. He had allies among the tribes at the mouth of the Rhine, and even won over a continental legion, denying a swathe of the European coast to Maximian’s armies. Soon, Boulogne, Rouen and Amiens had fallen into his hands.

The Roman historian Aurelius Victor, writing about 70 years later, credits Carausius as a skilful commander who protected Britain from warlike peoples – presumably referring to barbarians such as the Germanic pirates rather than Maximian’s forces.

Perhaps the most unexpected aspect of Carausius’s regime is its cultural pretensions. He flaunted Britain’s mineral wealth by minting high quality silver coins, which were not only better than anything the Roman empire had issued for over a century but extraordinarily diverse.

Carausius’s portrait looks rather thuggish: a close cropped beard and hair, a bull neck and beetling brow. It’s hard to imagine such a man having an interest in high culture. Turn the coins over, though, and we have a remarkable and varied image of Britain as Carausius wanted it. It is true that there are references to military might (legions and ships), but there is a strong emphasis on peace, and even images of rural idyll, such as a milkmaid milking a cow. Many of the designs are highly allusive and would have required a literary education to appreciate their full meaning.

Some Carausian coins bear the enigmatic letters RSR. For a long time, scholars argued over their meaning – were they a mintmark, or the initials of an official? The solution was provided by the historian Guy de la Bédoyère: it is an abbreviation of redeunt saturnia regna, “the dominions of Saturn return” – written three centuries earlier by Virgil in his poem the Fourth Eclogue, and a reference to the Golden Age, a kind of Roman version of Eden.

Guy de la Bédoyère’s theory was confirmed by a medallion of Carausius, bearing another abbreviation, INPCDA, which turns out to be the next line of Virgil’s poem, iam nova progenies caelo demittitur alto, “now a new generation is let down from high heaven”. These literary references – together with other Carausian coin inscriptions, such as revonat(or) romano(rum), “restorer of the Romans” – indicates that Carausius’s regime was familiar with Virgil’s poetry, and perhaps expected a literate audience in Britain to understand the abbreviations.

They suggested that Carausius would restore Rome to its Golden Age – not from Italy, but from Britain. To do so, Carausius needed to defend Britain from those who controlled Rome.

By AD 289, Maximian was preparing his invasion force, building a fleet and training sailors. A speech extolling him survives from this time, and foresees a glorious victory over the “pirate” Carausius. But it was not to be. Another speech in Maximian’s praise, composed two years later, passes over Carausius in silence. The attempt at invasion had evidently failed, and Maximian’s fleet had been bested or destroyed. That much we know from the fourth-century historian Eutropius, who bluntly tells us that Carausius’s military experience had prevailed. Maximian was forced to arrange an ignominious peace.

‘Brothers’ at war

Peace and accommodation may have been what Carausius had wanted all along. Once again, his coins provide evidence of his intentions. Carausius is shown shoulder to shoulder with Diocletian and Maximian, as their partner and equal. Carausius et fratres sui, reads the accompanying inscription (“Carausius and his brothers”). And, in an attempt to acknowledge Diocletian as the senior emperor, another coin reads, augustis cum Diocletiano (“To the emperors with Diocletian” – referring to himself and Maximian).

But Diocletian had no intention of recognising Carausius as a colleague. He would appoint his co-rulers, and would not have the decision forced on him.

Carausius’s victory was a threat to Diocletian’s authority. In AD 290 or 291 he met with Maximian to confer on a strategy to deal with the British usurper. Maximian was heavily engaged fighting Germans on the Rhine frontier, so Diocletian decided to appoint two new deputy emperors – but Carausius was not to be one of them.

Maximian’s deputy was Flavius Valerius Constantius, nicknamed Chlorus, or ‘Paleface’. An extremely gifted commander, Constantius’s brief was to destroy the British empire. But to invade Britain he would first need to conquer Carausius’s continental possessions. He began by laying siege to Carausius’s port at Boulogne (AD 293), which he captured more by luck than by skill when an ineffective mole he built to blockade the harbour fooled the defenders into surrendering. Then Constantius’s luck got even better. At some point, either shortly before or after the siege of Boulogne, news came that Carausius was dead.

A malignant foil

The circumstances of Carausius’s end are unclear, but the historical tradition implicates Allectus, the very man who succeeded Carausius as Britain’s second Roman emperor. If we know little about Carausius, we know even less about Allectus. Aurelius Victor tells us only that Carausius had placed him in charge of the treasury, but that he was caught embezzling, and killed Carausius to avoid punishment. Eutropius says merely that Allectus was Carausius’s ally.

Maximian and Constantius may have concocted the story of Allectus’s treachery in order to present their new opponent as an out-and-out villain. And that is his enduring reputation: a malignant foil to the gallant figure of Carausius. There are even hints in a speech praising Constantius that Allectus acted on the instructions of Maximian and Constantius, hoping to be recognised as co-emperor. Whether Allectus killed Carausius or not, the fact that he remained on the throne would suggest that he had plenty of support in Britain itself.

If Allectus imagined that by disposing of Carausius his enemies would recognise him, he was sorely mistaken. Even so, Constantius needed more ships to take on Allectus’s navy, and they would have to be built. It gave Allectus precious breathing space.

Evidence of Allectus’s preparations have been found at Pevensey Castle, near Eastbourne in East Sussex. Excavations in the medieval keep at the eastern end revealed the foundations of a Roman wall with wooden stakes driven into the ground. The timbers could be dated quite closely to AD 280–300 – the time of Carausius and Allectus. Coins of the two British emperors were also found. It suggests that Allectus was strengthening his defences, building on the legacy of Carausius.

When it came, the invasion was two-pronged. In AD 296 Constantius set out from Boulogne with one part of the fleet, while his praetorian prefect, Julius Asclepiodotus, sailed from the mouth of the river Seine with the other. But it was the British weather, rather than strategy, that proved decisive.

Part of Allectus’s fleet lay stationed off the Isle of Wight, ready to intercept the approaching force. Yet fog hid Asclepiodotus’s ships and he was able to sail past unimpeded, eventually landing somewhere in Southampton Water. Asclepiodotus then gave the order to burn the ships, committing his forces to the war in Britain, and marched inland, perhaps hoping to capture London.

Allectus, realising that he had been caught off guard, abandoned his coastal defences and set off with his army to block Asclepiodotus’s advance, but he was overwhelmed by the invading forces and cut down. The battle was over before Constantius even arrived.

The recovery of Britain is celebrated on the famous Arras Medallion – the largest of all Roman gold coins to survive to this day (shown above) – which depicts Constantius’s triumphant entry into London. Redditur lucis aeternae, the inscription reads, “the restoration of eternal light” (after the ‘darkness’ of Carausius and Allectus). Constantius is shown riding beside a ship to the gates of London, with a Londoner kneeling in supplication before him. Britain, the island at the edge of the world, had been restored to Rome. More importantly, Carausius’s powerful fleet was back in Roman hands.

Carausius and Allectus lived in a particularly obscure period of Roman history, and Diocletian and his colleagues did all they could to expunge them from history. Their coinage was probably demonetised and any monuments to them destroyed.

However, this alone cannot explain why they scarcely figure in the national consciousness today; after all, we have made heroes of equally remote historical figures. Past attempts to incorporate them in a national narrative failed to take hold. In the 12th century Geoffrey of Monmouth retold their story in garbled form and, 600 years later, the antiquarian William Stukeley used Carausius’s coins to show how Britain had once succeeded as a great naval power (both writers had a wild imagination!)

The Victorians far preferred the ‘High’ Roman period of Augustus and Hadrian (which they regarded as a model of empire) to the perceived decadence of the third and fourth centuries. Carausius and Allectus had nothing to say to the myth-makers of that age – and maybe, as an immigrant from the continent, Carausius was deemed unsuitable.

Yet as the first rulers to demonstrate that Britain could operate as an independent economic and naval power, Carausius and Allectus deserve to be better known. They represent an axial moment in the history of these islands, though the facts are scarce.

Even their ultimate failure to hold on to Britain is a potent legacy. The success of Diocletian’s new Roman empire depended heavily on the British empire’s defeat and, had Allectus’s fleet intercepted Asclepiodotus off the Isle of Wight in AD 296, history might have taken a very different course. Constantius would have been discredited; his son, Constantine the Great, might never have become emperor after him. And there might have been no Christian Roman empire at all.

Kevin Butcher is professor of classics and ancient history at the University of Warwick. His books include Roman Syria and the Near East (J Paul Getty Trust, 2004).

In context

Roman Britain’s century of chaos

For the Roman empire, the third century AD was a time of political unrest, usurpations and barbarian invasions. For a few decades it looked as if the Roman empire was on the brink of disintegration as rival emperors struggled for supreme power or declared themselves independent.

Contemporary historical sources are scarce. Historians are often forced to reconstruct events of the period from chance finds – coins, inscriptions and the occasional references in ancient literature. The reigns of Carausius and Allectus are no exception.

For much of the third century, Britain survived the troubles relatively unscathed. There are even signs of the province’s increasing self-sufficiency and prosperity. From AD 260–73 it became part of a breakaway empire established in Gaul under the rebel emperors Postumus, Victorinus and then Tetricus.


In the later part of the century Britain began to suffer from attacks by Germanic raiders, and after the fall of this ‘Romano-Gallic’ empire in 273 the central powers may not have offered effective protection. The growing economic independence of Britain could have paved the way for political and military separatism born of disillusionment with Rome. There are hints of a failed British usurpation during the reign of Probus (AD 276–82), only a few years before Carausius’s rebellion succeeded. The sentiments that created the first British empire may have been in the making well before Carausius.