16

THE CONSTANTINIAN EMPIRE

Constantine, in 324, enjoyed total control over his empire. The victory over Licinius meant that no viable challengers remained, unless they were to come from his own family. It also gave Constantine control of the frontier with Sasanian Persia, and a new and still wider horizon for his expansionary imagination to contemplate. It was an interesting time in Persia, for the young shahanshah Shapur II was just attaining his majority. Though he would go on to prove as formidable a ruler as his third-century namesake, the years of his minority had not been easy. Narseh had died in 302 or 303 and was succeeded by his son, Ohrmazd II (r. 302–9/10). We know very little about Persia under Ohrmazd, since the late Arabic sources contain little reliable information. Upon his death, and probably after a rebellion, he was succeeded by Shapur II (309/10–79), who was in 309/10 only an infant. His accession looks like a coup on the part of some of the nobility and priesthood against the older sons of Ohrmazd. Although the 310s are something of a blank in Persian history, by the early 320s Shapur had begun to assert his own authority. Around 324 or 325 his brother Ohrmazd (Hormisdas, to the Romans) went into exile at the court of Constantine, and probably shortly thereafter Shapur personally led an army deep into Arabia, disciplining Sasanian clients there, and perhaps seeking to undermine Roman control of trade routes to the Far East. During that expedition, or at least probably related to it, there were skirmishes between Persians and Romans along Rome’s Arabian limes (the Strata Diocletiana discussed in chapter 12), seemingly with real Roman losses. For the most part, Shapur first concentrated on consolidating his power in the satrapies of his empire, but in time he and Constantine would enter into a conflict that was sustained for more than a generation.

Constantine found in the east a very different world than the western empire he had left behind. Beyond the obvious contrast of Greek and Latin cultures, the two regions had had entirely different experiences of persecution in the previous decade. Not only had there been many more Christians in the east than in the west, but they had suffered more and for longer. What is more, Greek Christianity was much more complex than Latin Christianity. In part this was a matter of language – Greek is capable of much greater subtlety than Latin and can produce almost infinite variations of meaning through the coining of new words out of existing morphological elements. Latin, with a smaller vocabulary and a greater resistance to neologism, was far less suited to theological or philosophical nuance, the same words often doing duty for many different things. For that reason, even native Latin speakers had often chosen to write in Greek when they turned to philosophical topics in the early imperial period – we saw this with the emperor Marcus Aurelius in his Stoic notes to himself. For the same reason, Greek thinkers rarely felt a need to learn Latin. But this linguistic complexity had consequences for Greek Christanity.

Constantine’s new faith, as we have seen, was predicated on belief more than practice, and failure to work out right belief compromised salvation. Abstruse problems of definition – things that would have been a matter of heated and competitive debate among philosophers, even dogmatic Platonists – became for Christian theologians matters of life and death, because they might mean the death of Christian souls, and the subtlety with which Greek could create variation of meaning provided almost limitless space for alternative propositions. Right belief was not, of course, something out there waiting to be discovered, but rather a construct forged in the hurly-burly of theological argument. Formulations that lost in this battle of ideas would be condemned as heresy, wrong belief, but there were problems: not only might one churchman’s heresy be another’s orthodoxy, but the moment a formula was accepted as orthodox or a question appeared to be settled, the settlement would produce new questions and with them new, and often equally divisive, formulae.

When Constantine defeated Licinius and took over the east, he found himself in the midst of one of these theological controversies. The problem revolved around the relationship of the three persons of the Christian trinity – the father, son and holy spirit – and in particular the way God the father was related to God the son. The contested ideas had been proposed by an Egyptian priest named Arius, and the long theological battle that ensued is now universally known as the Arian controversy. Unlike his rather limited engagement with the Donatists of North Africa, Constantine’s intervention in the Arian controversy was shockingly bold and, briefly, decisive; it would have momentous consequences for the future of the Roman empire, both politically and culturally.

Egypt and its main episcopal see at Alexandria had experienced similar problems to those that created the Donatist schism in Africa – who could be admitted to communion with the church after having made some accommodation to the Roman state during the Great Persecution. But in Egypt, unlike in Africa, the problem of the traditores was linked – opportunistically by one party to the controversy – to a genuine theological problem. Arius, who had studied at Antioch, objected to the views of the Alexandrian bishop Alexander on the likeness of God the father and God the son in the Christian trinity. If, Arius argued, God the father had ‘begotten’ God the son, then there must have been a time when God the son had not existed, and in consequence they could not share the same substance, but rather God the son must be both different from, and subordinate to, God the father. Alexander exiled and sequestered Arius in response to this challenge, which he considered not just insubordinate but heretical, but Arius searched out and found powerful political supporters in other churches of the east.

Once the intellectual question of who was right in his description of the relationship between the father and the son in the trinity became politicised, it did so not merely in pure intellectual terms, but also according to who knew whom along the networks of friendship and patronage that influence thinking in any society. These networks each besieged Constantine’s court from the moment he defeated Licinius, knowing not only that he could be asked to render an enforceable judgement, but that as a member of their faith he would feel obliged to do so. Leaning on the same conciliar solution with which he had tried to settle the Donatist controversy in the west, came, in the east, to exacerbate both the intellectual problem and its political dimension, because it enshrined a technique of constructing orthodoxy that was intrinsically fraught with dangers: it asked groups of bishops, men who were used to dominating their own communities, to seek compromise on questions where the stakes were as high as they could be. Free rein was thereby given to jealousy, vanity and status hierarchy among clever and ambitious men who could claim, and generally believed, that other people’s souls depended on their being right. In theory, a council’s decisions were not just binding, but divinely inspired. In practice, they were political as much as theological, and attended by the bitterness and recrimination that a process with plenty of losing parties will always produce. In the three centuries during which Christians were either ignored or persecuted by the Roman state, conciliar or episcopal decisions could be enforced only by mutual consensus among communities of believers. Constantine’s conversion, and his decision to put the full weight of the Roman state behind conciliar decisions, instantly sharpened the edge of church politics.

We see this with the council of Nicaea, called to address the controversy over the teachings of Arius. Constantine had long taken advice from bishop Hosius (or Ossius) of Corduba in Spain, in all likelihood the person who had convinced him that his visions in Gaul were a Christian not an Apollonian portent. Faced with the rivalry of bishops who favoured and those who opposed Arius, Hosius advised the calling of a council, to which all the bishops of the empire were to be invited. It was held at Nicaea, in Asia Minor, a location convenient for the bishops of most of the east. The number of bishops who attended is canonically accepted to have been 318, but the true number is impossible to come by. Eusebius of Caesarea, who would write the first history of the church, which culminated, in its later editions, with Nicaea, is not just one of our foremost sources, but one of the dozens of important bishops we know to have been present. These included both senior Christian leaders who bore the scars of the Diocletianic persecution and the representatives of the holiest sees of the east: Alexandria and Antioch. Though Eustathius of Antioch attended in person, Alexander of Alexandria sent a young deacon, Athanasius, as his representative, pleading old age. Given that the main controversy the council was meant to address concerned Alexander’s own priest Arius, the decision to leave matters in the hands of a young and politically vicious subordinate would prove to have major consequences.

Constantine and Hosius, however, were clearly trying to achieve both unanimity and the establishment of the true faith, and they cast the net wide: western bishops took part – from Gaul, Hispania, Africa, Dalmatia and Italy – as did bishop Eusebius of Nicomedia, whose importance rested both on his seniority and on his tenure of the episcopate in the main imperial residence in Asia Minor. Eusebius was one of the supporters of Arius, having shared a teacher with him, and, although they were in the clear minority at Nicaea, they put up a vigorous argument in the presence of the emperor himself: Constantine insisted on debating as an equal among the assembled bishops, an audacious but characteristic move.

There is no need to go into the details of the theological debates that took place at Nicaea, in part because reconstructing them with precision and a lack of confessional partis pris has been the work of centuries. But that said, we should simultaneously stress their importance, for even deeply devout believers in the twenty-first century are hard-pressed to conjure the significance that late ancient Christians placed on precise theological accuracy. It will suffice to say that, after considerable debate, airings of intellectual positions and callings-in of political favours, Arius’s contention that God the son was the first creation of God the father and thus different in ‘being’ or ‘substance’ (ousia and substantia in the respective Greek and Latin) of God the father, was rejected. In its place was mandated a formula by which God the father and God the son were – in Greek – homoousios, or identical in being or substance (homoousios is a compound of the Greek words for sameness and being). This Nicene formula absolutely excluded the possibility of ‘substantial’ difference between the persons of the father and the son, despite the creation of the one by the other, and if the reader suspects a paradox, a leap of faith will surely be needed to overcome it. That said, the formula was a success in the moment: it satisfied those who believed Arius was irredeemably unorthodox and who wanted to ensure a settled theological solution he could not possibly subscribe to; it also satisfied those who wanted merely to please the new eastern emperor and emerge from the contest unscathed, since the new emperor clearly thought the Nicene creed was a winning proposition; and even those who thought that the homoousian formula was intellectually indefensible – Eusebius of Nicomedia chief among them – found it good enough for the needs of the moment. In that they proved right. All but three bishops subscribed to the conciliar creed produced, Arius and the other recalcitrants went into exile, and there the matter was meant to rest.

Of course, like the Donatist schism in North Africa, it did not. Not only those who genuinely agreed with Arius found the Nicene formula discomfiting. There were many who thought Arius quite wrong, but who also thought the homoousian solution equally, if differently, wrong. That was a recipe for ongoing conflict, and conflict was what it generated. Athanasius of Alexandria and those on the winning side who agreed with him had a deep political investment in maintaining the Nicene formula against all challenges. When Athanasius succeeded Alexander as bishop of the Egyptian metropolis in 328, the stage was set for perpetual trouble. Eusebius of Nicomedia, in particular, was very close to the emperor, becoming closer to him as Constantine aged. As the reign progressed he did his best to ensure that others sympathetic to the views of Arius filled eastern bishoprics. These bishops – derisively called Arians by their opponents, but better styled ‘homoians’ for the formula they advocated – suggested that instead of father and son having an identical substance, they were actually alike in substance, homoios. By the time of Constantine’s death, the emperor himself had come to see Athanasius and those who followed him as not merely more wrong than their opponents in theological terms, but more dangerously obstructive as well.

We could fill several pages here with an account of the machinations, political and theological, that followed from Nicaea, and it is true that theological controversy is one of the dominant themes of late ancient history and of the literary sources it has left us. But the point that is at present crucial for us is structural. Nicaea and its aftermath made the emperor and his officials responsible for enforcing conformity with one form of Christian belief against another. This was very different from the enforcement of sacrifice under Decius, for instance, where the goal was to enforce conformity of practice, not of belief. What Constantine had committed himself and his officials to enforce was something not susceptible of proof. Christian controversialists understood this, and seized upon it for its political utility. In the long run, the state was forced to expend vast resources on defining and enforcing what people should profess to believe, a process that created entire classes of people who were excluded from the state and its protections because they would not conform to the formulation of Christian belief endorsed by the emperor.

The discovery and enforcement of orthodoxy was not the only measure Constantine took in favour of the church. Throughout the east, Constantine sent officials out to catalogue and plunder the treasuries of pagan temples. Temples were huge repositories of wealth, having long served the Greek world as a combination of banks and museums; many of them held gifts going back 500, 600 and 700 years. Constantine took all of this gold and other treasure to finance two of his most ambitious projects: the construction of Constantinople and the monetary reform that we will consider later in this chapter. The confiscations were not intentionally planned as means of suppressing pagan belief. If they had been, Constantine would not have placed a leading pagan, the Eleusinian hierophant Nicagoras of Athens, in charge of seeking out precious monuments from Egypt. Nevertheless, the sudden impoverishment of many great temples did more damage to traditional Hellenistic religions than did any other measure Constantine took against them. One of these other measures is a source of great controversy because it is surprisingly difficult to document: it is quite probable that Constantine banned pagan sacrifice in public, not just blood sacrifice, but also the symbolic lighting of incense at the shrines of the gods. No contemporary source unequivocally attests such a ban, but a pagan Greek poem alludes to altars which no longer smoke, and a law issued by Constantine’s son Constans in 341 bans public sacrifice and claims that Constantine had already done so in the past. The balance of probability does therefore suggest that Constantine banned public sacrifice, but equally suggests that the ban was not very strictly enforced – rather like the Great Persecution, it must have depended largely on the attitudes of officials on the spot. In another manifestation of his Christian beliefs, in 324 Constantine invented the weekend by declaring that no public business should be conducted on the day sacred to the sun. (Only agricultural labourers continued to be required to work every day of the week – an interesting persistence of the old Graeco-Roman sense that only men who lived in a politically defined and urban place were fully human.)

Among these varying signs of favour towards Christians, Nicaea clearly remains the pivot on which the story of Constantine turns, not just because of its importance, but because of the distribution of surviving evidence: after the closing of the council, the narrative history of the reign becomes difficult to plot apart from intermittent glimpses. The most dramatic moment was the execution of the caesar Crispus and the disappearance or execution of Fausta. Crispus was killed at Pola in May 326, having been summoned there to answer unspecified charges. Because Constantine was so consummate a manipulator of his own reputation, there is no way of knowing what actually happened. A late fourth-century pagan source, Eunapius (as transmitted in the still later Historia Nova of the pagan Zosimus), suggests that Crispus and Fausta had an affair and that, after Crispus’s execution, Constantine’s grief drove him to kill Fausta as well. Another version had her go into exile and die a few years after Crispus. It seems that contemporaries knew very little, and as a result we know still less. A liaison between Crispus and Fausta is by no means impossible – they were much the same age – but Constantine’s fear of a coup is more likely. Crispus had done well in the war against Licinius and he had been groomed for power for a decade as the face of imperial government in the west. To westerners dissatisfied with a distant and perhaps radically Christian Constantine, Crispus might have looked like an attractive alternative. Constantine may have been right to suspect his son of dangerous ambition, or he may have been duped into killing a loyal lieutenant. What is certain is that Constantine was in Rome in July and August 326 when Crispus was executed at Pola. The caesar’s memory was never rehabilitated, but Fausta’s name was eventually restored to the imperial ancestry after her sons succeeded to their father’s throne.

Constantine’s movements in the later 320s can be traced in the places from which he issued laws. He spent the winter of 326–7 in the Balkans, and then, in late spring 327, travelled to Asia Minor via Thessalonica and Constantinople, presumably to check on the progress of his new city. During December 327 and January 328 he took part in a church council at Nicomedia that worked out the further consequences of Nicaea’s rulings. While doing so he probably refounded the city of Drepanum, a Bithynian polis near Nicomedia, as Helenopolis, in honour of his mother Helena, who had by now taken on a prominent public role as a patron of Christianity. By May, however, he had left Asia Minor for the Balkans: we find him at Serdica in the middle of that month, then moving on to Oescus (a town, now uninhabited, north-west of Pleven in Bulgaria), before making a journey to the Rhineland that autumn, presumably to placate local elites who regretted the death of Crispus. He overwintered in Trier, but also did some campaigning beyond the Rhine, presumably against one or another group of Franci. In March he was back in the Balkans and he spent almost three years there, including a full year in his new residence of Constantinople after its formal dedication on 11 May 330. He shuttled between Constantinople and Nicomedia in 331, mainly addressing ecclesiastical issues, but in early 332 he returned to the Danube, where he launched a war that would have large consequences for future events.

We know more about Constantine’s Gothic campaign than we do about most late imperial frontier actions, but what we know is in some ways more tantalising than informative. By the later 320s the land from what the ancients called Lake Maeotis (and we call the Sea of Azov) to the Carpathians was under the hegemony of Goths, people who both identified themselves and were identified by Romans in that way. Even the mention of non-Gothic polities disappears in the region after the last tetrarchic war against the Carpi, although that does not mean that most of the regional population was ‘Gothic’. Goths seem to have been the dominant group in a society that included a lot of subjects who were not recognised as Gothic, though they all shared the distinctive material culture known as Sântana-de-Mureș/Černjachov. The older populations – Carpi, Dacians, former Roman provincials, Sarmatians – did not disappear, but were now ruled by Goths, whom Roman sources divide into two main groups, the Tervingi and the Greuthungi. As we have seen, these Goths were not ethnically homogeneous migrants from elsewhere, but a product of the Roman frontier and the various peripheral cultures that mingled there. The real proof of growing Gothic strength in this period is the terminal decay of the Bosporan Greek kingdom towards the end of Constantine’s reign, and its final disappearance in the mid fourth century. No wonder we find the left bank of the Danube called the ripa Gothica (‘the Gothic bank’) at just this time.

It is not at all clear what prompted Constantine’s Gothic war in the 330s. He may have intended to punish the Goths for fighting on the side of Licinius in their final civil war, or he may have become alarmed at the way tetrarchic support for the Goths against Carpi and Sarmatians had allowed the Tervingi to consolidate power so quickly. Constantinian building projects, the financing of which is evidenced by a dramatic increase in the region’s supply of bronze coinage in the late 320s, included a major wall system in the valley of the Porecka near the Iron Gates and an ambitious new bridge over the Danube from Oescus to Sucidava, completed in 328. The base at Sucidava established an imperial bridgehead on the ripa Gothica and continued a tetrarchic project to fortify the Danube frontier with so-called quadriburgia. These were small forts, enclosing less than two and a half acres, with a tower at each of their four corners. They were built both in the Roman provinces of Moesia Secunda and Scythia as well as on the other side of the river, and Constantine erected a new quadriburgium at Daphne, opposite Transmarisca (Tutrakan). Campaigning on the left bank is attested in 328 and 329.

Then, in 330, some Taifali – a minor group identified in the sources as being ‘Goths’ – invaded the Balkan provinces, perhaps fleeing from the Tervingi, because there soon followed an embassy from the Sarmatians, requesting imperial aid against the latter. Constantine’s Gothic campaign followed ‘in the lands of the Sarmatians’, conducted by his eldest surviving son Constantinus, Crispus’s successor as senior caesar. The campaign ended in a major imperial victory, with the Goths handing over hostages that included the son of a Tervingian king named Ariaric, who clearly ruled a substantial polity and who may have been the grandfather of the Gothic king Athanaric who would fight the emperor Valens to a standstill in the 360s. The Romans followed up this victory with a campaign against their Sarmatian allies, who had supposedly proved unfaithful to their agreements with the emperor. Even two decades later, Constantinus’s victory was remembered as particularly dramatic and it ensured peace on the Danube for more than thirty years.

Scholars have built elaborate hypotheses upon the extremely poor fourth-century evidence for the peace treaty’s terms, often retrojecting sixth-century evidence with no relevance to 332. For contemporaries, ‘the Goths finally learned to serve the Romans’. They offered tribute to the emperor, provided a reservoir of recruits for imperial campaigns, and the Danube frontier was opened to trade all along its length. This was unusual given Rome’s long history of restricting the export of Roman technology, but the large quantities of bronze coinage from the 330s to the 360s found on both banks of the river suggest that commerce surged and Gothia became well integrated into the Roman monetary economy. Roman diplomatic connections with the Gothic elite, meanwhile, are attested by large quantities of silver coins, normally found in small hoards distributed across the whole of Gothic territory. Since silver had by now ceased to play any meaningful role in the Roman economy itself, these may have been minted as bullion for gift subsidies to Gothic chieftains, or as discharge packages for Gothic soldiers serving in the Roman army: silver would have been useful as a means of exchange eastwards into the steppe and Sasanian worlds, where the economy was entirely silver-based. If so, it is evidence for the ways Rome could accommodate its practices to a Eurasian context.

A final consequence of Constantine’s interest in the Goths was the spread of Christianity beyond the frontier. Inside the empire, Constantine took various measures against paganism but did nothing to actively encourage conversion. Outside it, he was a busy proselytiser. He saw himself as a bishop to those outside the empire, called to evangelise the gentes beyond the frontier, but also making conversion a tool for diplomacy binding the faithful to the empire and its emperor’s personal religion. Predictably enough, however, this activity made Christians look rather like a fifth column in non-Roman territory, and not just among the Goths. Constantine supported Christian missions to a variety of kingdoms beyond the empire. During the reign of Licinius, in 313 or 314, the Armenian king Tiridates III had converted to Christianity, inspired by the bishop of Cappadocia, Gregory (known as the Illuminator). Armenian influence probably led to the spectacular conversion of Caucasian Iberia, along the eastern coast of the Black Sea south of Lazica, as the old Hellenistic kingdom of Colchis was now called.

Unlike Armenia, which was always torn between the Roman and the Persian worlds, Iberia had long been firmly in the Iranian orbit, its ruling elite generally subscribing to the Zoroastrianism of the neighbouring Arsacids and Sasanians. Then, a wonder-working Christian holy woman converted the Iberian king – perhaps Meribanes (Mirian) III, a staunch Roman ally – and he set out to convert his kingdom: an embassy to Constantine was met with great approval and the emperor began to subsidise missionary work and church-building projects in Iberia that would lead to conflict with Persia later in the fourth century. The Iberian alliance was important for another reason as well, for it is almost certainly in Iberia that a hitherto unknown source of very fine gold was discovered in the last decade of Constantine’s reign or shortly thereafter; that new eastern gold had a profound impact on the fourth-century economy, and on the respective fates of the eastern and western empires in the fifth.

Another mission field for the zealous emperor was Axum, ancient Ethiopia. Recent research has shown how the Red Sea zone – including Axum on the one hand and Himyar, now Yemen, on the other – was much more closely connected to the Roman and Persian worlds than was previously thought. Indeed, a long-lasting Jewish kingdom in Himyar is of great significance for the later rise of Islam and the end of the ancient world. In the Constantinian period, however, the conversion of Axum closely paralleled that of Iberia: two Christian slaves belonging to a travelling philosopher named Meropius found themselves in Axum, where they were freed, one of them entering the service of the king, the other returning to the Roman empire and becoming bishop of Tyre while maintaining connections with his old companion. This companion, Frumentarius, converted king Ezana, and Christians from the empire were then granted privileged access to Axumite trade.

Athanasius of Alexandria, the expert controversialist whom we met at Nicaea earlier in this chapter, claimed responsibility for policing the orthodoxy of the Axumites. Orthodoxy, as Constantine’s intervention at Nicaea had demonstrated, was a matter for imperial politics. In the same way that the rise of the Sasanians had gradually brought the Roman empire into contact with wider Eurasian history, so too did the replacement of the pragmatic cult of the early empire with an aggressive imperial Christianity extend the imperial gaze out to wherever there were Christians to protect or regulate.

The stories of both Iberia and Axum’s conversion are filtered to us through layers of pious fiction and the kind of legendary distortion that infects all Graeco-Roman accounts of distant lands that were known mainly through a mixture of merchants’ tales, very rare diplomatic embassies and the overlay of Classical mythology and Hellenistic romance. By contrast, the Gothic conversion is fairly well attested: the treaty of 332 did not impose Christianity on Ariaric’s Goths but, by the time of his death, Constantine had sponsored the mission of a Gothic bishop named Ulfila, sometimes called Wulfila or Ulfilas. Our information on the life of Ulfila derives from two sources: a letter written by one of his disciples, Auxentius, and a heavily abbreviated version of Philostorgius’s fifth-century Ecclesiastical History. Ulfila was descended from Cappadocians taken captive in the Scythian raids of Gallienus’s reign, though he himself bore a Gothic name. He came from Gothia on an embassy to the emperor – probably Constantine, perhaps Constantius II – and was consecrated in either c. 336 or c. 341 by Eusebius of Nicomedia and other bishops. Eusebius, as we have seen, was an adherent of the post-Nicene homoian theology, towards which Constantine was increasingly inclined in his later years. It is clear from the bishops who consecrated him that Ulfila was a member of the homoian party, and so the earliest evangelism among the Goths brought Christianity in its homoian form. Gothic homoianism was later heavily re-enforced in the reign of Valens, and homoian doctrine and a liturgy in the Gothic language would remain a distinguishing factor between Romans and Goths until the sixth century.

After his consecration, Ulfila was meant to serve as bishop to all the Christians in the land of the Goths, but we have no idea how many such people there were, how many were, like Ulfila, descended from Roman captives and how many were converts won beyond the frontier. But within a decade of Ulfila’s arrival, Gothic leaders were becoming worried at the growing number of Christians and began their persecution. We will look at the consequences of Gothic conversion in the sequel to this volume, but here we can understand the story of Ulfila in the context of the missions to Axum, Armenia and Iberia. All are symptoms of a new phenomenon in fourth-century imperial history: elites from regions not actually administered as provinces becoming integrated into the imperial elite, participating in its governance in much the same way as did provincial elites from regions subject to imperial administration. We will have more than one occasion to consider this structural change in imperial politics, inaugurated by Constantine, which meant that later in the century Franci and Alamanni, Mauri from the North African steppe, Iberians and Saracens, exiled Persian royals and Goths – all could make good careers in imperial government, some retiring back to their homelands beyond the frontier, others settling down as honoured grandees inside the empire. It is all a world away from the senatorial elite of the Antonine period with whom our story began.

To return to our fragmentary narrative of Constantine’s last decade, the short-term consequence of the emperor’s Gothic victory was merely to shift the focus of confrontation to a new set of barbarian enemies. In 334, as we saw, Constantine campaigned against the Sarmatians, probably those that had asked for his help against the Goths in the first place. We are told that the servile population of the Sarmatian lands rebelled against their masters, and that many Sarmatians – 30,000, according to one source – fled into Roman service. Once inside Roman territory, they were divided among the Balkan and Italian provinces. That is a reminder of just how effective the Roman state remained at managing the mass relocation of large populations, although it involved keeping an eye on, and preparing for, the upset of old power hierarchies in the barbaricum. We should understand this Sarmatian relocation as the last major consequence of rising Gothic power during the tetrarchic period. In fact, it was not until the 370s that the lands beyond the Danube were again similarly disrupted.

After the 334 campaign, Constantine took the victory title Sarmaticus maximus to accompany his multiple acclamations as Gothicus maximus. He also took the title Dacicus maximus, which probably represents a claim to have restored Trajan’s province of Dacia. The Carpathian lands of the old province were certainly not reannexed and subjected to Roman administration, but new garrisons in trans-Danubian quadriburgia and other small forts justified the claims. Constantine was a familiar and frightening force beyond the limes, as is illustrated by the large number of barbarian ambassadors present in 335 at the celebration of his tricennalia, his thirtieth anniversary on the throne, which is described to us by Eusebius of Caesarea, an eyewitness. Here we find not just the expected Goths and Sarmatians, but also Blemmyes, from south of the Roman frontier in Upper Egypt, as well as Ethiopians and Indians. This latter testimony is not as far-fetched as some might think, for as we shall see India was much on the mind of the Constantinian court towards the end of the reign.

The tricennalia was a major event, for it had been a very long time since any emperor had lived long enough to reach a thirtieth anniversary. During the celebrations, Constantine and Fausta’s middle son, Constantius, was wedded to a daughter of Julius Constantius, Constantine’s half-brother, with great pomp and circumstance. Perhaps the most significant thing to note, however, is where the celebration took place: Constantinople. Even Diocletian and Maximian, whose interest in the city of Rome was minimal, had felt it essential to travel there to celebrate their vicennalia in 303. Now, only just over thirty years later, Constantine felt no such compulsion. Constantinople would not be recognised officially as the new Rome until the 380s, but few things make clearer its status as the second city of the empire than the fact that Constantine chose to celebrate so momentous an occasion there.

Constantine would rule for just two years after his tricennalia and these were spent planning for the succession and plotting another war against Persia. War had been brewing since 324, when Constantine received the brother of the Persian king Shapur II (r. 309–79) under his protection when the latter fled to Roman territory. This Hormisdas (Ohrmazd), as he was known to Greeks and Romans, was a major figure at the eastern court for many years after that, but harbouring a competent adult pretender was an affront that Shapur felt strongly – not least because Constantine took in Hormisdas at more or less the same moment that the shah had written to congratulate him for his victory over Licinius and to welcome him into the fellowship of monarchs. Constantine’s reply had hectored Shapur about the need to protect his Christian subjects, and had also denounced the Mazdaism of the Persian court as a false religion. The conversion of Iberia to Christianity was another incursion into the Persian zone of influence, fuelling Shapur’s resentment, but it was an Armenian succession crisis that, as so many times in the past, led directly to the war with Persia.

The Christian Tiridates III died in 330 and his only son was a minor. The Armenian nobility, which played a decisive role in many successions, was divided along pro-Roman and pro-Persian lines, with various family jealousies playing their part as well. Unsurprisingly, those nobles who favoured the Roman side chose Tiridates’ young son Arsaces, but others sent to Shapur asking him to give them a king. Civil war broke out in Armenia, Arsaces fled to Constantine and Shapur invaded the kingdom and raided the easternmost imperial provinces. Constantine gave Arsaces shelter, but did not try to restore him to his throne; instead he proclaimed Hannibalianus, the younger son of his half-brother Flavius Dalmatius, as ‘king of kings and of the kingdom of Pontus’. This proclamation was the proximate cause of war but, in the wake of the tricennalia and its show of universal rulership, it was also said that Shapur had stolen the gifts sent by the rulers of India to acknowledge Constantine as their ruler of thirty years. Even discounting the characteristically Constantinian propaganda in that rumour, we should not doubt that he thought he could conquer Persia. Constantine shared with many a Roman emperor the fantasy of surpassing Alexander, of taking his conquests as far as the eastern sea – wherever that was – and he had won so many battles that he might justifiably think himself capable of making the fantasy real. He chose as his excuse the fate of Christians in Shapur’s realm, which was as convenient as any other, and the dynastic arrangements adumbrated at the tricennalia of 335 telegraphed his ambitions: the appropriation of the title ‘king of kings’ for Hannibalianus (his rex regum in the Latin calqued from the Persian ‘shahanshah’) was as provocative as it was speculative.

Along with the marriage of Constantius, which cemented Constantine’s lineage to the cadet branch of his half-siblings, the tricennalia made clear the settlement that the emperor wanted to bequeath posterity. At least since the execution of Crispus, the three sons of Constantine by Fausta had been groomed for the succession as Constantine had been four decades earlier. Constantinus was permitted to cover himself in glory in the Gothic wars of the early 330s, and in 335 Constantius was very nearly old enough to be entrusted with a political role. Constans remained too young to command armies, but it was now he who represented the face of the dynasty to the Italian nobility, residing at Mediolanum and betrothed to Olympias, daughter of Constantine’s powerful praetorian prefect, Flavius Ablabius.

By contrast with the children of Fausta, Constantine’s half-siblings and their offspring – the sons, daughters and grandchildren of Constantius I and Theodora – were kept in the shadows. They seem, wisely, to have supported their victorious half-brother while keeping out of his way, until the tricennalia changed the political calculus. Whether through megalomania or mere realistic ambition, Constantine had determined that nothing short of world conquest would suit; his three surviving sons were too few to make that happen, and his father’s collateral offspring had to be made an asset if they were not to be a threat. Not until the tricennalia did the extent of the plan become clear: as we have seen, Hannibalianus, the son of Constantine’s half-brother Flavius Dalmatius, was proclaimed king of kings, but he was also married to Constantine’s daughter Constantina. Flavius Dalmatius’s other son, like his father called Dalmatius and until 335 still a schoolboy under the famous Gallic rhetor Exsuperius of Narbo, was now raised to the rank of caesar. He and his brother were thereby given parity of rank with Constantine’s own sons, and the younger Dalmatius was probably, if not certainly, married to Constantine’s youngest daughter Helena. To drive home the point of the succession plan, each of Constantine’s four caesars was assigned his own residence and his own praetorian prefect: Constantinus at Trier, Constans at Mediolanum, Dalmatius probably at Sirmium, and Constantius at Antioch. Constantius would oversee the muster of a campaign army, while Constantine travelled to Palaestina to receive baptism in the river Jordan en route to the conquests that would deliver Shapur’s Persian throne to the young rex regum Hannibalianus.

It was early in 337 when Constantine set out from Constantinople for Antioch. He was expecting many more years of triumphs before the succession he had arranged with such theatrical splendour actually took effect, but expectations failed him: falling ill just after departing Nicomedia, he became too weak to travel. Prostrate in a mansio of the imperial postal service, he accepted baptism from his long-time episcopal favourite Eusebius of Nicomedia and died on 22 May. The emperor’s middle son, Constantius, got word of what had happened and hurried as fast as he could from Antioch. Meanwhile, Constantine’s body was embalmed and carried in state back to Constantinople for a massive funeral that took place as soon as Constantius had arrived.

Constantine was buried in the mausoleum of the Twelve Apostles, a monument he had himself commissioned in the city that bore his name: in his own mind, at least, he had been a thirteenth apostle. We do not know when the obsequies were finally concluded, or when the interment actually took place, but on 9 September Constantius, along with his elder brother Constantinus and his younger brother Constans, were proclaimed augusti. Their cousins Hannibalianus and Dalmatius did not share this happy outcome, or take up the inheritance promised them at their uncle’s tricennalia: both were dead, murdered along with all their male relatives save two very small children, Gallus and Julian, one the full brother, the other the half-brother, of Constantius II’s wife. The tripartite succession of Constantine and Fausta’s sons meant that the late emperor’s own plans had outlived him by less than three months. A new era was inaugurated by an orchestrated massacre that has correctly been described as a ‘summer of blood’.