The Life and Times of the Roman Usurper Constantine III (AD 407-411)
Most people have heard of Constantine the Great (AD 306-337), the first Christian emperor and the guy who made his faith the preferred religion of the Empire. However, unless you are really into the weeds of late Roman history like I am, you almost certainly have never heard of Constantine III (AD 409-411). There's a good reason for that. While Constantine's cameo on the historical stage was short and violent, he played a supporting role in the unraveling of the Western Roman Empire in the early fifth century.
We know little about Constantine the man. If we had more details, his life would offer ample material for a Shakespearean tragedy. This Constantine rose from obscurity to the heights of power before seeing it all come crashing down a few years later. At his apogee in AD 409, he even got the Western Roman Emperor Honorius (AD 393-423) to recognize him as co-emperor.
Alas, his moment at the pinnacle of power was brief; just as quickly as he rose, he fell. Such was the fate of yet another of late Rome's many usurpers. The tomb of the Western Roman Empire became filled with ambitious gamblers like Constantine III, making him memorable mostly as a case study of political dysfunction and decay.
Still, it's worth looking at his life and times. We see in Constantine the symptoms of Rome's decline all packed into one short four-year period. You get rebellion, barbarian invasions, even more rebellions, and then some more barbarians, all trapped in a doom-loop spiraling toward disintegration.
This post will take a brief look at the world as Constantine III would have found it in AD 406. This was a centuries-old Pax Romana on the cusp of falling apart. Under Constantine's watch, Britain left the Empire for good; Gaul, Spain, and Africa would follow in the coming decades. A weak child-emperor ruled the Western Roman Empire at a time of prolonged existential crisis. No savior would emerge this time to save Rome as Aurelian and Diocletian had in the third century. Roman and barbarian warlords sprouted up like weeds in a neglected garden, and they would eventually choke that garden to death. Constantine III was one of the first of those weeds, and he would not be the last.
Britannia in AD 400: The Calm before the storm
"The regular forces which guarded that remote province had been gradually withdrawn, and Britain was abandoned without defense to the Saxon pirates and the savages of Ireland and Caledonia. The Britons, reduced to this extremity, no longer relied on the tardy and doubtful aid of a declining monarchy." Edward Gibbon
First, by all appearances, Roman Britain (Britannia) in AD 400 was still a flourishing outpost of the Empire, and there was no reason to think this would change anytime soon. To someone in early fifth century Britain, over three centuries of Roman rule must have made it seem eternal. Yes, there was the occasional crisis, but Rome always protected its borders, whether that by building Hadrian's Wall to guard the northern frontier, or erecting coastal forts, the so-called "Saxon Shore" safeguarding the coastline against raiders. Rome had protected Britain well over the centuries.
Therefore, few people alive in AD 400 would have believed that within a decade, Roman rule in Britain would end, initiating a centuries-long era of barbarism that eradicated most of its Roman heritage. Then again, an astute observer of the time may have noticed that all was not as stable as it seemed.
Villa culture, a tell-tale sign of peace and prosperity in the later empire, was by AD 400 in a steady decline (Southern 338). The increasing frequency of Saxon and Pict raids made life more precarious for the Britons. For example, the British provinces were plundered during a major barbarian incursion in AD 367-368. The Empire sent reinforcements to restore order, but significant damage was done before they could do so.
It turns out this problem was not limited to Britain.
Elsewhere, cracks were appearing on Rome's frontiers. Emperors spent most of their time campaigning on the Rhine, Danube, and Persian frontiers against an increasingly formidable array of enemies. They were always on the move with large mobile field armies, dashing to and fro along the borders to confront emerging threats. Co-emperors were needed to manage such an immense Empire. Unfortunately, this was a recipe for civil war.
Destructive civil wars had become a recurring theme since the third century. By the AD 380s, the Empire was proving less resilient at bouncing back after these repeated and extended bouts of civil strife. Each struggle pitting Roman versus Roman sapped the Empire's strength at a time when external threats were increasing.
At least three of these major civil wars occurred between AD 383-407: first, out of Britain came the revolt of Magnus Maximus between AD 383-389. After Maximus was eventually defeated by emperor Theodosius (AD 379-395), Britannia returned to the imperial fold, though there is evidence that it was never fully integrated as before (Kulikowski 152). The second was the usurper Eugenius (AD 392-394). Theodosius eventually defeated him at the bloody and costly Battle of the Frigidus in AD 394. Constantine III's revolt in AD 407 marked the third major civil war in 25 years, two of which had originated in Britain.
This was Britain as Constantine III found it in the early fifth century: superficially stable but structurally fragile.
Before returning to Constantine, let's look at events elsewhere that were critical in setting in motion his ill-fated rebellion in AD 407.
The Rotten Center - The Disastrous Regime of Honorius
"The emperor Honorius was distinguished above his subjects by the preeminence of fear, as well as of rank. The pride and luxury in which he was educated had not allowed him to suspect that there existed on the earth any power presumptuous enough to invade the repose of the successor of Augustus." Edward Gibbon
After Theodosius died in AD 395, he left two sons: the older, Arcadius, ruled the Eastern Roman Empire while the other, a child of eleven, Honorius, ruled the western half. Though he would reign until AD 423, Honorius's only talent was an uncanny ability to stay in power. He did so for thirty years, despite being a weak and inept ruler. His reign saw warlordism take firm root in the western provinces. Court factions and usurpers spent just as much time stabbing each other in the back as they did in dealing with Rome's enemies. This would have calamitous consequences.
With the imperial center lacking a strong leader, rivals for power went at each other like scorpions in a bottle, often at a high cost to the state they were charged with defending. As Roman fought Roman to fill the power vacuum left by the new regime's incompetence, Rome's enemies took notice.
As weak as he was personally, Honorius still had the legitimacy and the authority of the mighty imperial administrative apparatus at his disposal. He was the legitimate successor of the respected Theodosius and was recognized as such by the court of the Eastern Roman Empire in Constantinople. These facts mattered a great deal. Nevertheless, Honorius's docile nature meant he never became more than a puppet emperor, beholden to whichever court faction was ascendant at the time.
And unlike his father and the other emperors of the fourth-century, Honorius spent his reign cowering within Ravenna's walls rather than at the head of an army confronting Rome's foes. He delegated his martial responsibilities to subordinates who would use and abuse that power for personal gain as much as they did to buttress the regime they served. He was the first stay-at-home emperor since the god-awful Elagabalus (AD 218-222) in the early third century, and it couldn't have come at a worse time.
Alaric's Goths had been a constant threat since their victory at Adrianople in AD 378. Ever since then, they had remained within the Empire's borders, sometimes as allies, sometimes as foes, but never as subjects.
On the Roman side was Honorius's talented commander, Stilicho, who led Rome's armies ably until Honorius had him murdered in AD 408. Stilicho had defeated Alaric's invasion of Italy in AD 401 and was the best counter to the Goths that the Romans had at the time. Still, palace intrigues hampered him, making Western Roman foreign policy inconsistent. But to be fair, Stilicho wasn't above doing a little scheming of his own.
A series of foreign policy dominoes would begin falling in AD 405 when King Radagaisus led a large Germanic force that penetrated all the way into northern Italy. Stilicho stripped bare the defenses along the Rhine to meet this threat. After a short, bloody campaign, he succeeded in defeating and killing Radagaisus.
Unfortunately, his victory proved short-lived. On New Year's Eve of AD 406, a massive confederation of barbarians (Vandals, Suevi, and Alans) broke through the now-depleted frontier defenses and plundered the Roman cities in the Rhine and northern Gaul regions. Stilicho could do little about it since events in northern Gaul had become peripheral to imperial politics at this time. While Radagaisus was vanquished, Alaric's Goths remained a threat closer to home.
And like Alaric's Goths, this newest mass migration across the Rhine was one-way, beginning an exodus that would take them from Germany through Gaul to Spain, and finally on to Carthage in North Africa over the next three decades. Now two large barbarian groups (Alaric's and the Vandal confederation) were loose within the Western Roman Empire's borders. It is a sign of the West's weakness that it was no longer strong enough to push them back across the Rhine. On the contrary, both groups began peeling away the Western Empire's core provinces and tax base, one by one.
By the end of AD 406, Stilicho and Honorius were focused on Alaric's large Gothic force in Noricum (modern Austria) and the threat it posed to Italy, though they would take a swipe at eliminating Constantine in Gaul during the next year. They were right to prioritize Alaric, even if they failed to stop him.
Constantine III's Rise (Restitutor Rei Publicae - Restorer of the State)
With the western regime unable to defend its periphery, its citizens there began looking to their own defense. In AD 407, the Roman field army in Britannia revolted. The chronology here is a little hazy. We don't know if Britain revolted in response to the AD 406 barbarian invasion of Gaul or whether the barbarian invasion was in response to Constantine III's revolt against Honorius. Roman historian Zosimus hints that it was the former:
"Some years before, Arcadius being in his sixth consulate, and Probus was his colleague, [AD 406] the Vandals, uniting with the Alans and the Suebi, crossed in these places, and plundered the countries beyond the Alps [Gaul]. Having there occasioned great slaughter they likewise became so formidable even to the armies in Britain, that they were compelled, through fear of their proceeding as far as that country, to choose several usurpers, [that is] Marcus, Gratian, and after them Constantine." Zosimus 6.3.1
Though Constantine was the third choice to lead this revolt, he was the first one not murdered by the disgruntled troops. Such had been the fate of the first two claimants, Marcus and Gratian. An ordinary soldier of humble birth, we're told that he was raised to the purple for no other reason than because of his illustrious name (Orosius). In any case, Honorius and Stilicho now faced a dangerous rebellion in Britain combined with a significant barbarian incursion in Gaul.
Constantine gathered most of the British field army and, like Maximus 24 years earlier, advanced into Gaul. He won some minor victories over the barbarian confederation that helped consolidate his support in Gaul. The barbarians were driven back to the Belgicas provinces (roughly modern northeastern France) but still remained within the Empire's borders and lived to fight another day (Goldsworthy 296, Zosimus 6.3.2). The Spanish provinces also soon joined Constantine's cause. After these initial gains, Constantine was able to restore some of the abandoned defenses along the Rhine. However, he soon had to deal with more pressing matters in the south (Zosimus 6.3.2).
Honorius wanted to snuff out this new rebellion before it gained momentum and sent his general Sarus with an army to restore order. Sarus routed Constantine's vanguard, killing his commander Justinian, and then besieged another, Nebiogast, at Valentia in southern France. Nebiogast came out to meet Sarus under solemn oaths of safety to discuss peace terms. Sarus, apparently not a man of his word, had him executed on the spot (Zosimus 6.2.3-7).
Off to a rough start, the tide soon turned in Constantine's favor. A counterattack raised Valentia's siege and drove Sarus back over the Alps and into Italy (Zosimus 6.2.3-7). Thus ended the first phase of the rebellion by the end of AD 407. Constantine held Britain and Gaul. He was also was consolidating control of Spain. An uneasy truce emerged between Honorius and Constantine. Both had other things to deal with.
Honorius, Stilicho, and Alaric - The Roman Game of Thrones
For Honorius, Alaric's position in Noricum made him an immediate threat to Italy. Alaric was demanding 4000 Ib of gold to not invade. Stilicho wanted to placate Alaric with the gold so he could hire his army to attack Constantine (Goldsworthy 296). Stilicho argued that the greater good could be served by paying the ransom. Thus, one of Rome's enemies could be paid to eliminate another. It would have been quite a stratagem if it had worked. In the end, Stilicho got his way, but it was a costly victory. Capitulating to Alaric's demands was deeply unpopular, with one Roman senator named Lampadius declaring, "Non est ista pax, sed pactio servitutis ("This is not peace, but a pact of servitude") (Goldsworthy 298).
Stilicho's position was already dangerously weak because he had failed to eliminate Constantine earlier. It now became even more so when the Eastern Roman Emperor, Arcadius, died in AD 408. Rumors swirled that Stilicho was going to march on Constantinople to install his son as emperor. In any case, he never got that chance, if such was his plan. A conspiracy backed by court factions and endorsed by Honorius brought down the great general.
Run to ground by one of Honorius's officers, Heraclianus, Stilicho took sanctuary in a church, coming out only on the solemn promise that his life would be spared. When he came out, Heraclianus, apparently also another man not apt to keep his word, had him beheaded. Stilicho's son and closest supporters soon after shared the same fate (Goldsworthy 298). Such was the end of the great Stilicho.
Of course, the problem for Honorius was that he didn't have another general nearly as talented as Stilicho. The foolish emperor was surrounded by wolves but had killed his best guard dog. Now Constantine threatened Italy from the west while Alaric threatened from the north. It looked terrible for the young emperor.
Perhaps seeing Alaric as the more pressing threat, Honorius recognized Constantine III as co-emperor of the West in AD 409. This was actually a reasonably astute move because it temporarily removed one foe to allow him to focus on the other. Astute or not, Honorius and his team totally botched what came next.
Without Stilicho as a check, Alaric descended upon Italy and besieged Rome twice. Honorius refused to agree to Alaric's demands, even though Italy was utterly at the mercy of the wily Goth. Alaric wanted the best of both worlds: official recognition and titles from Honorius while maintaining his independence by commanding an army personally loyal to him. Finally fed up with Honorius's refusal to give him what he wanted, Alaric sacked the Eternal City in AD 410. Rome, glorious Rome, the center of the civilized world for over six hundred years and untouched by foreign enemies for over eight hundred years, suffered the humiliation of a sacking.
A later legend circulated that when the messenger brought Honorius news of Rome's fall, he was at first terrified that something awful had happened to his favorite chicken, oddly also named Rome. Discovering that the messenger was referring to Rome, the city, Honorius sighed in relief (Kulikowski 149).
Constantine III's Fall
After he took Gaul, Constantine focused on consolidating his position there and expanding into Spain. But it turns out Constantine's military situation was becoming even more dangerous than his rival's. He had more vexing problems to deal with. In Spain, things quickly fell apart. Constantine's commander, Gerontius, revolted (AD 409) upon hearing rumors that he was to be replaced. (Goldsworthy 303). The barbarians Constantine had beaten earlier but not destroyed were making their way through Gaul on the way to Spain. One source states that Gerontius stirred them up to weaken Constantine. That's exactly what they did.
At one point in AD 410, there were six men claiming to be emperor: Honorius for the Western Romans, Theodosius II for the Eastern Romans, Constantine and his son Constans in Gaul, Gerontius's creature Maximus in Spain; and Alaric's puppet Attalus in Rome (Bury 192). Such was the new normal of late Roman politics.
By AD 411, Constantine's position was in freefall. He had more enemies than resources to deal with them. This is informed speculation, but it's quite likely that he had spread himself too thin.
Remember, Constantine had sailed from Britain with the British field army. The Gaul they arrived in was stripped of its best troops by Stilicho to confront Radagaisus. Those troops never returned. As mentioned earlier, Constantine had followed up his early victories against the barbarians by re-manning the old defenses along the Rhine. Doing so would have thinned his army out even more. Plus, the early defeats at the hands of Sarus would have taken a toll.
Even worse, the forces Constantine dispatched to Spain under Gerontius had rebelled. By this point (AD 411), what was left of his own field army was very likely quite modest. Constantine thus found himself fighting a three-front war (Gerontius, Honorius, and the barbarians), and with not much of an army left to lead against them.
To make matters worse, Britain, perhaps tired of paying taxes to absentee rulers that would not or could not defend it, had revolted one last time in AD 409/410, throwing out Constantine's administrators. This proved to be the end of Roman Britain.
This time, no leader like Maximus or Constantine arose to make a bid for the imperial prize. The locals decided that enough was enough, better to use their limited resources to defend themselves rather than sending them to fund civil wars. And so, just like that, Britain simply broke away from the Empire, never to return (Kulikowski 153).
Elsewhere, Honorius had finally found a worthy replacement for Stilicho, a man named Constantius. Alaric, the conqueror of Rome, had died (AD 410) a few months after taking the city. The interregnum gave Honorius an opportunity to square accounts with his beleaguered co-emperor to the west. Seeing how desperate Constantine's cause had become, he dispatched Constantius with an army to finish him off. Constantine's former ally, Gerontius, was by now (AD 411) besieging him at Arelate (modern Arles). Constantius advanced into Gaul and scattered Gerontius's forces before then taking over the siege.
Constantine took stock of his situation.
Britain was gone, not that it would have offered much help. An army raised in northern Gaul to relieve the siege was destroyed outside Arlelate, ending any last hope for a military victory. Spain was now being overrun by Vandals, Alans, and Suevi, and so was lost. By AD 411, he held little more than his capital at Arelate.
Constantine was beaten, and everyone knew it. Game over.
In AD 411, he agreed to surrender to Constantius with the solemn promise that he could take vows and become a priest. On the way back to Ravenna, however, Constantine was beheaded. Apparently, Honorius was not a man of his word.
So ended the short career of Constantine III. The damage was done, however. The Western Roman Empire never got either Gaul or Spain more than nominally back within the imperial orbit (Kulikowski 162). Britain was gone forever. The Vandal-Alan-Suevi confederation had made its way to Spain where they divided up the province amongst themselves before moving on to Africa in the AD 430s. The Visigoths settled in southern France and later in Spain. The Roman provincials soon learned to make peace with their new masters.
The next few decades saw the Western Roman Empire's fortunes continue to slide. Barbarians came and settled. Romans continued to fight Romans. Even though the names changed, many others very much like Constantine III would make reckless bids for power.
Unfortunately, the West would be "blessed" with another stay-at-home child emperor after the hapless Honorius died in AD 423. This was the equally ineffective Valentinian III, who would guide the Western Empire through another thirty years of dismemberment and collapse. By his death in AD 455, most of Gaul north of the Alps, North Africa, and Spain were gone. The Western Roman Empire staggered on for another two decades. However, by now, the political dysfunction and military decay that had marked Constantine's brief historical moment had acquired unstoppable momentum. The Western Romans were done. It was only a matter of time.
Bury, J. B. From the Death of Theodosius I to the Death of Justinian. Dover, 1958.
Gibbon, Edward. The Decline and Fall of the Roman Empire. Modern Library, 2003.
Goldsworthy, Adrian Keith. The Fall of the West: the Slow Death of the Roman Superpower. Weidenfeld & Nicolson, 2009.
Kulikowski, Michael. The Tragedy of Empire: from Constantine to the Destruction of Roman Italy. Belknap Press of Harvard University Press, 2019.
Orosius, Paulus. Histories against the Pagans. Para. 3 ed., Book 7, attalus.org/translate/orosius7B.html.
Southern, Pat. Roman Britain: a New History 55 BC - 450 AD. Amberley, 2011.
Zosimus. “Zosimus, New History 6.” Livius, www.livius.org/sources/content/zosimus/zosimus-new-history-6/.