A short history of Byzantium

A short history of Byzantium: No. 18 Constantius II, the Byzantine autocrat (Part 2)

The real danger to the Roman empire often came, not from its citizens, nor the Christians, as some would like us to believe, but from its war-monger generals. So often in its long history generals have played their part in bringing about instability and civil war. The appetite for power repeatedly produced usurpers who looked to legitimise their rule through fear, bribes and reward. Flavius Magnentius, the commander of the Gallic armies was no different, when he boldly hired assassins to hunt down and murder Constans. 

Along the way Magnentius also eliminated Nepotianus, the half-nephew of Constantine the Great, who dared to raise a band of gladiators to try to stop him. Strategically though, he couldn’t gain control or the support of the all-important Danube legions commanded by Vetranio. Vetranio had thrown his own hat in the ring to stop Magnentius lightning rise to power by assuming the title of Caesar. Nonetheless, apart from this small setback, Magnentius still gained control of vast territories of the empire in Africa, Italy, Gaul and Spain. Though, if he expected to be received with opens arms by Constantius II, he was seriously mistaken.

Constantius, who had been preoccupied with war against Shaphur, as previously mentioned, was finally free to avenge the death of his brother by 350 AD. He had left Gallus in charge to watch over the eastern provinces and felt comfortable enough that Shaphur would honour the truce struck between them. With this done, he marched his army into the Balkans, where he received the submission of Vetranio’s army.

Vetranio was an interesting character, even if his name is only briefly linked in Constantius story. At first, Vetranio seemed loyal to Constantius, in protecting the interests of his family, but later it seems, he dared to issue an ultimatum with Magnentius, for Constantius to abdicate the throne. When Constantius refused and responded in kind by advancing into the Balkans, Vetranio prostrate himself before Constantius and unconditionally surrendered his claims to Caesar. Some believe Vetranio was a puppet of Constantius, while others say that the only thing that saved Vetranio was his submission to Constantius. Either way, in an act of reconciliation, Constantius allowed Vetranio to retire and live out the rest of his life in private, far away from the temptations of power.

With the Danube armies now secure under his control, Constantius shrewdly sent his Praetorian prefect to negotiate with Magnentius. Constantius had hoped to avoid more needless Romans bloodshed, by commanding Magnentius to withdraw his forces back to Gaul. Stubbornly Magnentius refused to see sense in a diplomatic solution, which inevitably meant the two great armies would fight. Even more disturbing news for Magnentius was that one of his most senior commander, Silvanus, deflected to Constantius’ camp. The deflection of Silvanus was a coup for Constantius because with Silvanus possibly came large numbers of men loyal to him.

Constantius, to this point, was a veteran of almost a dozen major battles. He backed his own judgement and the strength of his armies to overcome adversity, however, not even he could have predicted the cataclysm that would unfold in the forthcoming battle at Mursa (now Osijek, in Croatia) on the Danube in 351. When the two armies of Constantius and Magnentius eventually clashed, blood spilled everywhere in what became the bloodiest battle of the fourth century. For the first time in Roman history, heavy cavalry inflicted great losses to Roman legions too. Upwards of 50,000 casualties and losses were recorded between the two armies. For Magnentius, the Battle of Mursa Major was a disaster, losing almost two-thirds of his strength, forcing him to retreat. Constantius on the other hand thanked God he had prevailed.

Constantius didn’t immediately take advantage of Magnentius predicament, he decide to first strengthen the Danube frontiers against Sarmatians. Only once he thought he had subdued them, did he continue his pursuit of Magnentius. He forced Magnentius out of Italy and into southern Gaul by the year 353. It was here that the end was near for Magnentius at the Battle of Mons Seleucus. After witnessing the surrender of his troops to Constantius, Magnentius once again fled in humiliation. Disheartened at his failed attempt to oust the dynasty created by Constantine, Magnentius committed suicide not long after.


Near the end of Magnentius reign, he boldly issued bronze coins featuring a Chi Rho in an attempt to persuade Constantius of his support for Christianity. Magnentius himself was a pagan. Constantius likely saw right through this political stunt finally crushing his resolve to resist in Gaul in 353.

Constantius had only a short time to pause and enjoy his victory over Magnentius. Pressing issues surrounding the instability of the frontier borders would trouble Constantius in the mid 350’s, with the Franks along the northern stretches of the Rhine and the Alamanni in the Danube. With so much internal strife over the past few years, it was about time the empire got back to the business of worrying about external factors like the raiding barbarians.

With this in mind, Constantius decided to reward Silvanus with command of the Gaul army to deal with issues along the Rhine Frontier. At first things went supposedly well as Silvanus bribed the Germanic tribes to return to their homes. Regrettably, internal issues within the ranks of the Roman army would rear its ugly head again, as fake letters damned Silvanus, for conspiring to take the throne from Constantius. The paranoid Constantius feared that this latest development would gain traction, so he decided to immediately recall Silvanus before things really got out of hand. By all accounts Silvanus was innocent, but panic gripped him and he decided to risk everything and declare himself Caesar. Fortunately for Constantius, Silvanus’ short reign of twenty-eight days did nothing to trigger a new civil war. In no time at all Constantius had Silvanus butchered to death in 355 AD.

Constantius overwhelming fear of losing his grip of absolute power triggered a succession of further purges of senior commanders, including his young cousin Gallus. Gallus, who was merely supposed to act as Constantius’ eyes and ears in the east, didn’t do himself any great favours when his unruly conduct raised suspicions. Gallus, it seems, had entertained ideas of donning the imperial purple permanently. Consequently, Constantius summons Gallus to Milan, and along the way in Pula, situated at the southern tip of the Istria peninsula, had him put to death.


Gold Solidus of Constantius Gallus, the paternal cousin of Emperor Constantius II.

Fear of usurpation kept Constantius alert to all matters involving the potential rise of a future adversary. Furthermore, he soundly came to the conclusion that he was going to have to trust someone because he simply couldn’t control the whole empire from his temporarily base in Milan. If anything, history had shown that a senior Augustus, needed the support on a junior Caesar. He couldn’t just appoint anyone and reluctantly chose Julian, who unlike his brother Gallus, didn’t seem to harbour any visions of greatness.

Julian hatred for Constantius ran deep, ever since Constantius murdered his entire family some twenty years earlier. But he knew better than to show any public menace towards Constantius and promptly joined him in Milan. Constantius bestowed upon Julian the imperial honour of Caesar in 355 and immediately sent him to the Rhine frontier to grapple with the Germanic tribes. Lacking genuine skill as a commander and experience as a Caesar, didn’t stop Julian from quickly finding his feet. In time he also won over the affection of his legions and soon his great victories across the Rhine began to worry Constantius. But when was Constantius ever not worried about the success of others? From here on end Constantius made sure he kept his eye on his cousin.  

With the re emergence of Shaphur in the east, Constantius  in 361 demanded that Julian send his armies east to help him. It reality it was an attempt to weaken Julian’s command. Unfortunately this climate of mistrust, instigated primarily by Constantius, boiled over and a rebellion was sparked by Julian’s legions. They also at this point in time chose to hailed Julian as the new Augustus, which threatened to trigger a new civil war. Fortunately, the empire would be spared a new civil war with the untimely death of Constantius, who had fallen ill along his march to deal with Julian in 361. The empire stunned by the sudden death of Constantius, willingly accepted Julian’s rise to power. The time had come for the young Augustus to keep this new Christian empire moving forward. Unfortunately what the people of the empire didn’t realise was that Julian harboured ambitions to turn back the clock, to a more pagan past.


The reign of Constantius was set against the backdrop of Christianity’s rise. He had done enough to promote and alienate the church all at the same time. He was also a tyrant, murderer and some say an inept ruler all rolled into one. It’s hard to pinpoint ever a time or a place when Constantius was at ease with the world or in fact, ever happy. Though, we do get a glimpse of an Emperor content enough to indulge his pride and curiosity in a visit to the ancient capital of Rome in 357 AD. Resembling “the appearance of a triumphal procession” Constantius entered Rome like a long-lost sovereign. He was received by the senate of Rome, observed the courts, preformed imperial ceremonies and attended the games of the circus.

In his short thirty day visit, someone somewhere surely must have seen him smile at least once? No one likely remembers, but what they will never forget is that their emperor, devoid of personality, entered Rome immobilized like a statue. 

“Though he was very short he stooped when he passed under a high gate; otherwise he was like a dummy, gazing straight before him as if his head were in a vice and turning neither to right nor left.” – Ammianus Marcellinus.

Notes and Further Reading
Peter Brown, The World of Late Antiquity, Norton, 1989.
“the appearance of a triumphal procession…..”, Edward Gibbon, The Decline and Fall of the Roman Empire, Edited, Abridged and with a Critical Foreword by Hans-Friedrich Mueller, The Modern Library, 2013, p.368.
Adrian Goldsworthy, The Fall of the West: The Death of the Roman Superpower, Wiedenfeld & Nicolson, 2009
John Julius Norwich, Byzantium: The Early Centuries, Viking, 1988.
“Though he was very short he stooped…”, Ammianus Marcellinus, The Later Roman Empire: AD 354-378, Penquin Classic, 1995, p.101.
Photo Credit: The header image of the Missorium of Kerch depicting Constantius II on horseback with a spear appears to be in the public domain. The bronze coin of Magnentius and gold solidus of Gallus are both used under the Creative Commons Attribution-ShareAlike 3.0 license.

2 comments on “A short history of Byzantium: No. 18 Constantius II, the Byzantine autocrat (Part 2)

  1. Awesome! I really enjoyed reading both parts of this article. So what’s next? Life of Julian?

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