Constantine the Great (306-337 CE) was the first Christian emperor. You've probably heard of him. But unless you are deep into the weeds of late Roman history like I am, you've never heard of Constantine III (409-411 CE).
There's a good reason for that. While Constantine III'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 as it began to succumb to warlordism and foreign invasion.
We know little about Constantine, the man. But what we do know provides material for a Greek tragedy. This obscure soldier emerged from obscurity to the heights of power before seeing it all come crashing down a few years later. At his apogee around 409, he convinced the Western Roman ruler Honorius (393-423) to recognize him as co-emperor. Alas, his moment at the pinnacle of power did not last; just as fast as he rose, he fell.
Such was the fate of yet another of late Rome's many warlord usurpers. The tomb of the Western Empire overflowed with ambitious gamblers like Constantine III, making him memorable only as a case study of late Roman political dysfunction and decay.
Still, it's worth looking at his life and times. We see the symptoms of Rome's decline packed into his short, four-year period. You get rebellion, barbarian invasions, more rebellions, and some more barbarians, all caught in a doom loop that began spiraling toward disintegration.
This essay will examine the world as Constantine found it in 406. This was a centuries-old Pax Romana that appeared solid and eternal. After Constantine's revolt, Britain left for good; Gaul, Spain, and Africa would follow in the coming decades. A weak child emperor reigned during this prolonged period of crisis.
No savior would emerge this time to save Rome as Aurelian and Diocletian had done in the third century. Roman and Germanic warlords sprouted up like weeds in a neglected garden. Constantine 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"The regular forces which guarded that remote province had been gradually withdrawn, and Britain was abandoned without defense to the Saxon pirates and the savages of Ireland and Caledonia.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 400 was still a flourishing frontier province, with no reason to think this would change anytime soon. Three centuries of Pax Romana must have made it seem eternal to anyone alive in early fifth-century Britain.
Yes, the occasional crisis erupted on the island. Yet Rome always protected its borders, first by building Hadrian's Wall and later erecting coastal forts, the so-called "Saxon Shore," to safeguard the coastline against raiders.
Few in 400 would have believed that Roman power in Britain would end within a decade, inaugurating a centuries-long era of barbarism that eradicated most of its Roman heritage. Then again, an astute contemporary observer may have perceived the apparent stability as a mirage
Villa culture, a tell-tale sign of peace and prosperity in the later Empire, was in a steady decline by 400 (Southern 338). The increasing frequency of Saxon and Pict raids made life more precarious for the Britons. For example, the British provinces suffered greatly during a major incursion in 367-368. Rome sent reinforcements and the threat abated, but significant damage was done before they restored the situation.
It turns out this problem was not limited to Britain.
Elsewhere, cracks appeared on Rome's long borders. Emperors now spent most of their time campaigning on the Rhine, Danube, and Persian frontier against an increasingly formidable array of foes. Diocletian had realized the need for co-emperors to manage such a sprawling Empire. Unfortunately, Roman leaders peacefully co-existing with each other for the common good tended to be the exception rather than the norm.
Destructive civil wars had become a recurring theme since the third century. By the 380s, the Empire proved less resilient at bouncing back after each bout of civil strife. Every struggle pitting Romans against each other sapped the Empire's strength at a time when external threats were mounting.
At least three major civil wars took place between 383-407.
First, the legions under Magnus Maximus revolted in Britain in 383. After Maximus lost to Theodosius (379-395) in 389, Britain returned to the imperial fold, though there is evidence that it never was fully reintegrated (Kulikowski 152).
The second civil war pitted the usurper Eugenius (392-394) versus Theodosius. Theodosius finally triumphed at the bloody and costly Battle of the Frigidus in 394.
And last, Constantine III's revolt in 407, again in Britain, marked the third major civil war in 25 years.
This was the Roman world of the early fifth century: superficially stable but deceptively fragile. Before returning to our ill-starred protagonist, let's look at events elsewhere that were critical in setting in motion his doomed rebellion in 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 395, he left two sons: the older, Arcadius, controlled the eastern half of the Empire while the other, a child of eleven, Honorius, held the west in Ravenna. Though he reigned until 423, Honorius's only talent was an uncanny ability to stay in power. Despite being a weak and inept ruler, he did so for thirty years. During his troubled reign, warlordism took firm root. Court factions and usurpers spent just as much time stabbing each other in the back as they did dealing with Rome's enemies. This would have disastrous 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 supposed to defend. As Romans fought each other to fill the power vacuum left by the new regime's incompetence, Rome's enemies took note.
As weak as he was, Honorius still had the legitimacy and the authority of the mighty imperial administrative apparatus. He was the legitimate successor of the respected Theodosius and was recognized as such by the court in Constantinople. This mattered a lot.
Nevertheless, Honorius's docile nature meant he never became more than a puppet ruler, beholden to whichever court faction was ascendant at the time.
Unlike his father and the other warrior emperors of the fourth century, Honorius spent his reign cowering behind Ravenna's walls rather than at the head of a field 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 bolster the regime they served. He was the first stay-at-home emperor since the god-awful Elagabalus (218-222) two centuries ago, and it couldn't have come at a worse time.
Alaric's Goths had been a constant menace since their victory at Adrianople in 378. Since then, they had roamed the Balkans and northern Italy, fighting sometimes as allies, sometimes as foes, but never as subjects.
On the imperial side was Honorius's talented commander, Stilicho, who ably led Rome's armies until Honorius had him murdered in 408. Stilicho had defeated Alaric's invasion of Italy in 401 and was the only real counter to the Goths that the Romans had at the time. Still, palace intrigues hampered him, making foreign policy inconsistent. But to be fair, Stilicho wasn't above doing a little scheming of his own.
A series of foreign policy dominoes began falling in 405 when King Radagaisus led a large Germanic force that reached northern Italy. Stilicho stripped bare the defenses along the Rhine to meet this threat. After a short, bloody campaign, he defeated and killed Radagaisus.
Unfortunately, his victory proved short-lived. On New Year's Eve of 406, a massive confederation of barbarians (Vandals, Suevi, and Alans) broke through the now-depleted Rhine frontier defenses and ravaged northern Gaul.
Stilicho did little about it because north of the Alps had become peripheral to imperial politics at this time. While Radagaisus was vanquished, Alaric's Goths remained a real danger and much closer to home.
And like Alaric's Goths, this newest mass migration on the Rhine was one-way, beginning an exodus that would take them from Germany through Gaul to Spain and finally to Carthage in North Africa over the next three decades. Now two substantial groups (the Goths and the Vandal confederation) were loose within the Empire's borders.
It was a sign of the West's weakness that it now lacked the strength to push them back across the Rhine. Instead, both groups began peeling away the Western Empire's core provinces and tax base.
By the end of 406, Stilicho and Honorius were focused on Alaric's dangerous Gothic force in Noricum (modern Austria) and the threat it posed to Italy. They were right to prioritize Alaric, even if they failed to stop him.
But another usurper had sprouted up in Britain: Enter Constantine.
Constantine III's Rise (Restitutor Rei Publicae - Restorer of the State)
With Honorius unable to defend his imperial periphery, provincial Romans began looking to their own defenses. In 407, the legions in Britannia revolted. The chronology here is a little hazy. We don't know if Britain revolted in response to the 406 invasion of Gaul or whether that it happened because of Constantine III's revolt against Honorius. The historian Zosimus hints that it was the former:
"Some years before, Arcadius being in his sixth consulate, and Probus was his colleague, [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 Constantine was raised to the purple for no reason other than his illustrious name (Orosius). Now Honorius and Stilicho now faced a dangerous rebellion in Britain combined with a significant barbarian incursion in Gaul.
Constantine gathered the British legions and crossed the English Channel like Maximus 24 years earlier. He won some minor victories over the Vandal confederation, which helped consolidate his support. The barbarians were driven back to Belgica (roughly modern northeastern France) but 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 restored some of the abandoned Rhine defenses. However, he soon had to tackle more pressing matters in the south (Zosimus 6.3.2).
Honorius wanted to snuff out this new rebellion before it gained momentum and so sent his general Sarus to restore order. Sarus routed Constantine's vanguard, killing his commander Justinian, and then besieged another, Nebiogast, at Valentia. Nebiogast met Sarus under solemn oaths of safety to discuss peace terms. Sarus, apparently not a man of his word, had him executed then and there (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 407. Constantine held Britain, Gaul, and part of Spain.
So far, so good.
Honorius, Stilicho, and Alaric - The Roman Game of Thrones
For the moment, Honorius had to focus elsewhere. Alaric's position in Noricum made him an immediate threat to Italy. Alaric was demanding 4000 Ib of gold not to invade. Stilicho wanted to placate Alaric with the gold so he could then hire his army to attack Constantine (Goldsworthy 296). Stilicho argued that the greater good was better served by paying the ransom. Thus, one of Rome's enemies would 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 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 became more so when Arcadius, the ruler of the East, died in 408. Rumors swirled that Stilicho would march on Constantinople to install his son on the throne. Whatever his true plans were, he never got the chance if such was his plan. A conspiracy hatched by venomous court factions and endorsed by Honorius brought down the talented 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, another man not apt to keep his word, had him beheaded. Stilicho's son and closest supporters soon shared the same fate (Goldsworthy 298).
Such was the end of the noble Stilicho.
Of course, the problem for Honorius was that he didn't have another general with Stilicho's military talents. The foolish ruler 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 fool.
Perhaps seeing Alaric as the more pressing danger, Honorius recognized Constantine as co-ruler of the West in 409. This was an astute move because it temporarily removed one foe to allow him to focus on the other. Astute or not, Honorius and his team botched what came next.
Without Stilicho as a check, Alaric descended upon Italy and besieged Rome twice. Honorius refused Alaric's demands, despite the fact that 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 loyal to him.
Fed up with Honorius's refusal to give him what he wanted, Alaric sacked the Eternal City in 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. Whether true or not, that's exactly what they did.
At one point in 410, six men claimed 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 in late Roman politics.
By 411, Constantine's position was in freefall. He had more enemies than resources and was getting overwhelmed. He had spread himself too thin.
Remember, Constantine had sailed from Britain with the British legions after the Rhine frontier had been stripped of its most experienced frontier troops by Stilicho to deal with the invasion by Radagaisus. Those troops Stilicho summoned to the south never returned.
Constantine had tried to capitalize on his early victories by re-occupying the abandoned Rhine defenses. But doing thinned his own forces out even more. Plus, the early defeats at the hands of Sarus had no doubt taken on toll on his available manpower.
What was worse, the forces Constantine dispatched to Spain under Gerontius had rebelled. By this point (411), what was left of his army was likely quite modest. Constantine was stuck fighting an unwinnable three-front war (Gerontius, Honorius, and the barbarians) with too few forces left at his disposal.
To make matters worse, Britain, perhaps tired of paying taxes to absentee rulers that didn't defend it, had revolted one last time in 409/410, throwing out Constantine's administrators. This time, no pretender like Magnus Maximus or Constantine III arose to make a bid for the imperial prize. The Britons 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 spiraled away from the imperial center, never to return (Kulikowski 153).
Elsewhere, Honorius at last found a worthy replacement for Stilicho, a man named Constantius. Alaric, the conqueror of Rome, had died (410) a few months after taking the city. The interregnum gave Honorius an opportunity to square accounts with his beleaguered co-emperor and rival to the west.
Seeing how desperate Constantine's cause had become, he dispatched Constantius to finish him off. Constantine's former ally, Gerontius, was by now (411) besieging him at Arelate (modern Arles). Constantius attacked 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. Constantine managed to raise a modest force in northern Gaul to relieve the siege, but that 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 also lost. By 411, he held little more than his capital at Arelate.
Constantine was beaten, and everyone knew it. Game over.
In 411, he agreed to surrender to Constantius with the solemn promise that he would take vows and become a priest. On the way back to Ravenna, however, Constantine was beheaded.
No surprise here: Honorius was not a man of his word.
The End
So ended Constantine III's short career. He left the the Roman West far weaker. Gaul and Spain never fully returned into the imperial orbit (Kulikowski 162). Britain fell away forever and soon entered a six century dark age.
The Vandal-Alan-Suevi confederation divided up Spain between themselves before moving on to Africa in the 430s. The Visigoths settled in Aquitaine and later in Spain after they drove out the Vandals. Roman provincials everywhere soon learned to make peace with their new overlords.
During the next few decades, the Western Empire's fortunes continued to slide. Barbarians came and settled. Romans continued to fight Romans. Though the names changed, many others similar to Constantine III would make reckless bids for power.
Unfortunately, the West was cursed with another stay-at-home child emperor after the hapless Honorius died in 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 455, most of Gaul north of the Alps, North Africa, and Spain were gone. The West staggered on for another two decades. No savior emerged this time to save the day. Those who tried, like Stilicho, Aetius and Majorian, were murdered for their efforts. The political dysfunction and military collapse first seen in Constantine III's brief historical reign acquired unstoppable momentum in the following decades. By the end of the fifth century, the Roman West was a motley assortment ruled by Goths, Franks, Saxons, Burgundinians, and Vandals.
Works Cited
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/.
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NOTE: Original published 30 October 2020 in Arles, France
Edits and updates made on 18 July 2023
P. Wilke