123 - The Tertrarchy

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Hello, and welcome to the History of Rome, episode 123, The Tetrarchy. I want to begin this week with a correction regarding the legend of Diocletian's ascension. As many of you have noted, the Doom Praetorian Prefect Lucius Aper's name does not translate into English as ass at all, but instead as boar. And it's a good thing that it does because when I went back and checked the supposed prophecy issued to young Diocletian, it actually says that he would gain the throne after killing a boar, not an ass as I said. So the pun still works, I just wrote down the wrong animal name when I was working up the outline for that week's show. I feel doubly silly for making this mistake, since way back during the episodes on the First Punic War, I told you all the story of how Gnaeus Cornelius Scipio managed to earn the cognomen Assina after leading the Romans into their first naval battle and consequently first naval defeat in 261 BC, Scipio the Ass they called him. Why I thought that Aper should now also translate as ass is a mystery for the ages. I regret the error and thanks to all of you out there who corrected the mistranslation with an official hat tip to listener LB for being first on the scene.

Last week, we covered the first few years of Diocletian's reign and specifically his decision to elevate his colleague Maximian to the rank of Caesar in 285 and then to Co-Augustus in 286. This week, we will see the Imperial College expand even further, as two more generals, Constantius and Galerius, will be invited to share in the purple in 293. This division of sovereignty at first proved to be an inspired move, and helped to ensure that Rome remained ascendant from Britain to Mesopotamia and everywhere in between. But eventually, the system will collapse when it comes time to hand off the so-called Tetrarchy to the next generation. But though it would not survive, the years of the Tetrarchy are amongst the most important in Roman history, and not just because they set the stage for the rise of Constantine the Great. Under the watchful eye of Diocletian and his colleagues, the Roman world will be transformed in ways both large and small to better meet the challenges that it now faced, all of which poses a bit of a problem for your humble podcaster.

You see, this fragmentation of Imperial authority leads to a fragmentation of the narrative, as now four separate centers of power are running four separate political and military apparatuses simultaneously, and when you couple this with the fact that along the way life as everyone knew it was being radically redefined, what you get is a big old mess. Say what you want about the drawbacks of Aurelian running around like a crazy person doing everything by himself, but at least it made for a coherent storyline. The 290s and early 300s AD, on the other hand, are a confused mess of war, politics, economic reform and social reconstruction all happening all at once. So what I've decided to do is to try to run the chronological narrative up to the beginning of the Great Persecution of 303 AD, which will take maybe two full episodes, and then we'll double back and cover the reforms Diocletian made to the military structure, the governmental apparatus, and the economic system, all of which may require separate episodes unto themselves, though I haven't yet decided how exactly I'm going to break it down. We are in the process of establishing the ground rules for Late Antiquity, so I don't want to gloss over anything, but I also don't want to get so bogged down that we don't make any forward progress at all.

Okay, are we ready? Here we go.

In the spring of 288, Diocletian arrived in Gaul to meet with his brother Emperor Maximian and help lay the foundation for the eventual retaking of Britain and the Gallic coast from the usurper Corotius. Without a fleet of their own, the two Augusti for the moment had to focus on pacifying the mainland so that when the inevitable invasion of Britain was launched, they would not have to worry about trouble from the Germanic tribes at their rear. For the rest of the year, they ran joint campaigns on the far side of the Rhine, with Maximian operating on the lower half of the river and Diocletian covering the upper half. It was a merciless scorched earth war that saw crops and livestock as much the target of legionary aggression as the tribesmen themselves, and by the end of the year, the exhausted and starved Germans were in no position to threaten Roman interests. Fortune was finally smiling on the Romans again, and the two Augusti even began the process of reoccupying portions of the Lyme East Germanicus that had been more or less abandoned some twenty years before. Satisfied with the hammer he had just laid on the Germans, Diocletian withdrew back to the east at the end of the year to keep an eye on the rest of the empire while his colleague was busy with the British question, and in the spring of 289, Maximian was ready to answer that question.

An invasion fleet had been under construction for some time, and now that the Germans were fairly well pacified, Maximian was able to use the Rhine delta as his launching pad into the North Sea. Though the Emperor had no choice but to attempt to retake Britain, from the very beginning he faced an uphill battle. Corotius and his navy were experts at navigating the rough northern waters, and their experience stood in stark contrast to Maximian and his utterly green navy. On top of that, Corotius had been hard at work fortifying the British coast, and in particular beefing up the so-called Forts of the Saxon Shore, a series of nine fortresses which though built at different periods, were very likely fused by Corotius into a single unit of command at this point in history. What this all meant is that even if Maximian ran Corotius' blockade, he would find no easy landing sites on the other side. But still, Maximian had to try, and so try he did.

It is perhaps not surprising that all we know today about the invasion of 289 is that it failed. Emperors were not in the habit of dwelling on their defeats, so it is only by way of a few passing references that we even know the attempt was made at all, and these diplomatically blame the weather for Maximian's failure to retake Britain. And who knows, maybe it was the weather. It's not like the North Sea and the English Channel are the calmest bodies of water in the world, but it's just as likely that Maximian's inexperience on the seas made him easy pickings for Corotius' expert fleet, and that it was man, and not nature, who drove the emperor back. Whoever it was, Maximian's fleet was destroyed, and Hercules was now further from recapturing Britain than he had ever been. As fast as the imperial post allowed, news reached Diocletian, who by that time had planted himself far in the east to help settle the new boundaries with Persia, and the no doubt severely disappointed emperor spent 290 A.D. making his way back to the west, very possibly forming in his mind the new New Order he would soon introduce to the world along the way.

Beaten and battered, Maximian at this point seems to have taken at least some note of what could now only be described as his shaky political position. Whatever the long-term consequences of Diocletian's new argument of rule by divine right, at that time, at that moment, legitimacy was still based on one thing and one thing only, military victory. Perhaps sensing that his subordinate commanders were salivating, Maximian secured the loyalty of the best and most ambitious of them all by arranging for the man to divorce his wife and marry Maximian's daughter Theodora, thus securing a familial alliance that Maximian hoped would help keep him propped up in power while he, or more accurately Diocletian, figured out what to do next. The man in question was a fellow Illyrian general with a naturally pale complexion by the name of Constantius Chlorus.

Constantius had been born around 250 AD in Illyria, so he was just about the same age as the man who was about to become his, quote, father. Though there is a whole tradition that has Constantius being the son of nobility, it is more likely that, like the rest of the Illyrian emperors, he was of low birth and that his son Constantine went back and gave his father a more prestigious pedigree to bolster his own imperial claims, specifically linking the family to the Emperor Claudius Gothicus by way of Constantius' mother Claudia. Whatever his genealogical heritage, Constantius proved his worth as a soldier right away, and while still in his early 20s, he was promoted into the ranks of Aurelian's elite bodyguard. Right around this time, he also sired a child with his wife Helena, a son who would become known as Flavius Valerius Aurelius Constantius, but who we know today as Constantine. Constantius, meanwhile, fought alongside Aurelian during the Palmyrene Wars, and then continued his climb up the ranks during the reigns of Probus and Charus, eventually finding himself governor of Dalmatia when the confrontation between Charianus and Diocletian exploded into open war, which meant that he was quite literally caught in the middle when the fighting began. But displaying some nimble prescience, Constantius declared for Diocletian right before the issue was decided, and it should be remembered, right before it was at all clear that Diocletian was going to win. And so he wound up squarely, but just barely, in the victor's camp in 285.

When his term as governor was up, Constantius was promoted to the position of praetorian prefect in the west in 288, where he continued to distinguish himself during the campaigns on the east side of the Rhine in preparation for the invasion of Britain. We don't really know what role Constantius played in the failed invasion of Britain, though as prefect he had to have been neck deep in the preparations, and later he showed very clearly that he had learned from the mistakes that were made in 289 when he initiated his own successful invasion. We also don't really know what long-term dynastic plans were at work when Maximian married his daughter to Constantius that same year. That is, did Constantius marry Theodora because Diocletian already planned to make him a Caesar, or was Constantius made Caesar because he was already married to Theodora? This question hinges on when Diocletian first conceived of the Tetrarchy, which is unfortunately a question we do not have a good answer to.

However, we do have a good answer as to when Diocletian probably first broached the subject of further dividing the empire with Maximian, and that would be over the winter of 290-291. By that time, Diocletian had traveled all the way back to Milan to meet with Maximian and shore up the regime after its nasty setback in the north. The two emperors oversaw solemn ceremonies and exuberant games to celebrate their rule, the peace and stability of the empire, and their mutual support for one another. Whatever else he took away from the pageantry, there was no denying that despite the recent failures, Diocletian still stood behind Maximian 100%. Over the course of the winter and the following year, the two men met often, and Diocletian likely laid out his plans for the future and what he expected of Maximian. Which is why some surmise that it was at this point that Diocletian revealed his plans to appoint junior colleagues to aid in their massive struggle to secure a bright future for the empire.

After the meetings in Milan, Diocletian headed back to his de facto capital in Nicomedia, while Maximian remained in Italy. Where exactly Constantius was at this point is unknown, but he was somewhere in the west, either seeing to things in Gaul or staying in Milan with Maximian. The whereabouts of the fourth member of our eventual tetrarchy, though, is an even greater mystery.

Though Galerius will soon emerge as a formidable force in Roman history, for example, in many ways he wound up being the unwitting author of Rome's Christianization, which is, uh, not a small thing at all, his life and career up to this point is shrouded in mist. He was born sometime between 250 and 260, and was probably slightly younger than Constantius, though not by much. Unlike the rest of his colleagues, Galerius also appears to have been born in Thrace, rather than one of the Illyrian provinces proper, and for a time, he followed his father as a herdsman before deciding to join the army, most likely during the reign of Aurelian. He too no doubt established himself as a highly capable soldier, because in just a few years he went from new recruit to high-ranking officer, and like his future colleague Constantius, he was very possibly appointed praetorian prefect by the late 280s AD, serving under Diocletian in the east. But beyond this, we know almost nothing about how Galerius managed to distinguish himself from all the other viable candidates when it came time for Diocletian to expand the imperial college. But distinguish himself he did, and in the spring of 293 AD, after much consideration and with so many of the empire's long-term problems still unresolved, Diocletian made the move to name two more members of the imperial brotherhood, and establish what we today refer to as the Tetrarchy, though it is important to note that like the first triumvirate, no one called it the Tetrarchy at the time.

In simultaneous ceremonies in Sirmium and Milan, the two Augusti each formally elevated a colleague to serve alongside them, Maximian investing Constantius, and Diocletian investing Galerius. To cement the imperial alliance, each new Caesar was married to the daughter of an Augustus, though the timing of these marriages is still a matter of debate. As I said, Constantius appears to have already been married to Theodora, which, if true, may have been the reason why he got the nod in the first place, and it is likely that Galerius too was already married to Diocletian's only daughter Valeria when he was elevated to power. Though this is all still up in the air, we know for sure that by 293, each man was the son-in-law of their respective Augusti.

Now, as with Maximian's initial elevation, Constantius and Galerius were not made full Augusti, but were instead raised to the rank of Caesar. Though they would outrank every other man in the empire, and would in their own territorial spheres have almost complete autonomy, they were most definitely styled as the junior partners in the equation. Maximian and Diocletian still outranked them, and by virtue of both his seniority and his overpowering gravitas, Diocletian outranked them all. The empire was then roughly divided in fourths, with Constantius taking Gaul and eventually Maximian in charge of Spain, Africa, and Italy, Galerius taking the Danube provinces, and Diocletian watching the far east. The split in provinces reflected the relative seniority of the Tetrarchs, with Diocletian and Maximian taking the rich and relatively peaceful portions of the empire, while their junior Caesars handled the much rougher regions along the Rhine and Danube frontier. Maximus in particular was given the toughest assignment of all, as it was made clear to him that his entire reason for being, and possibly the whole reason the new Tetrarchy existed at all, was that Britain had to be retaken. And retaking Britain, now seven years gone from Roman control, had proven to be an impossible task up to that point. So yeah, good luck with that.

Now before we go on, I should note that these territorial divisions were in no way officially demarcated political units, and in fact, every chance he got, Diocletian emphasized the unity of the empire. He was sensitive to the fact that Rome had just gone through a traumatic decade and a half where the empire really was divided from itself, and he was not keen to reopen that still healing wound. So he established a precedent whereby each of the Tetrarchs would share in the victories of the others, coin in each other's names, and come and go and shift spheres of influence as the situation dictated. As we will see, Diocletian and Galerius in particular would flip-flop depending on where the empire's fires were burning brightest. Power was being shared by four men, and for obvious reasons each established capitals allowing them to easily manage a different zone, but the empire is still one empire. It is not, Diocletian went to great lengths to express, nor will it ever be, he repeated again and again, four separate empires.

Following their respective elevations, the two new Caesars went to work right away. For Constantius, this meant heading north to Trier where he immediately began to prepare a second invasion of Britain. Galerius, meanwhile, immediately put lie to the notion that the Tetrarchy's territorial divisions were hard and fast by heading to Egypt to help quell an uprising on the upper Nile, and he spent most of the next two years pacifying the Egyptian natives.

While he was engaged in Egypt, events in Sassanid Persia hinted at what Galerius' next assignment would be. In 293, the Persian king Bahram II died, leaving the throne to his young son Bahram III. But just a few months later, Bahram III would be deposed by another of Sharpor's sons, a man named Narcis, who despised his weak-willed brother and nephew, and planned to reintroduce the martial vigor of Ardashir and Sharpor. In 295, Narcis broke the eternal peace that had been established with Rome in 287 by invading Armenia and seizing the territories that had been ceded by Bahram in his negotiations with Diocletian. Conflict between the two great empires was now inevitable, and Diocletian called Galerius to Antioch to begin preparations for war.

Back in the West, meanwhile, Constantius faced the question that had basically broken Maximian – how do we retake Britain? Now the new Caesar had some ideas as to how to run a better invasion than Maximian, and when it finally came time to take back the island, Constantius did run a much more strategically sound campaign. But the real problem, the big problem, was Corotius himself. The self-proclaimed Augustus of Britain and Northern Gaul was no dummy and he was no tyrant. By all accounts, he was a sound administrator, a savvy negotiator, a charismatic leader, and an excellent soldier. He was essentially everything that you would want in an emperor, and the citizens of his domains were highly conscious of that fact. The merchants loved him because he kept trade flourishing, his Frankish allies loved him because they were treated almost as equal partners, the legions loved him because he maintained high currency standards and was always on time with pay, and the general population loved him because he protected them from marauders and pirates. Corotius, much like Posthumus in the Gallic Empire, was a capable leader, leading capably. There was no reason for anyone to wish him ill will.

So when Constantius was working up his invasion plans then, he could pretty much bank on the fact that there wasn't going to be some fifth column working behind the lines for him. This was going to be an invasion of enemy territory in almost every sense of the word, and they had a better navy than he did, and their coastlines were fortified, and the British legions were well paid and well supplied. There was a reason Maximian had failed so completely, and it wasn't just that Maximian had screwed it all up. The recapture of Britain was a really, really hard assignment.

Next week, we will see the Empire at war on two fronts. In the east, Galerius will indeed be called upon to lead a counterattack against a resurgent Sassanid Empire, and though in the end he will avenge the memory of Valerian, at first, like so many Roman wars, things did not go well at all. In the west, however, things will go a bit better, as Constantius will carefully and methodically isolate Corotius by leading a brilliant little campaign against the Franks on the mainland. Then, he will be given the greatest gift of all, as Corotius, like Posthumus and Odonathus before him, will fall victim to an assassination plot that will leave Britain wide open for reconquest and allow Constantius to style himself the restorer of eternal light.