The immortal gods in their providence have so designed things that good and true principles have been established by the wisdom and deliberation of eminent, wise and upright men. It is wrong to oppose these principles, or desert the ancient religion for some new one, for it is the height of criminality to try and revise doctrines that were settled once and for all by the ancients, and whose position is fixed and acknowledged.
THE EMPEROR DIOCLETIAN, A.D. 3021
Despite the energy of emperors in their role as protectors of its frontiers, the Roman empire was always vulnerable to attack. The distance from the mouth of the Rhine to that of the Danube was no less than 2,000 kilometres, while the shortest marching route between the Black Sea and the Red Sea was 3,000. The borders of the provinces of Africa ran for 4,000 kilometres, often across empty desert. While small raids could be dealt with by local troops, any efficient invader who could rely on overwhelming numbers or surprise could easily break through. Once inside the empire, its fine road network brought the raiders quickly within reach of opulent and undefended cities.
Often the peace could be kept through diplomacy. It was essential to keep the many German tribes who jostled with each other along the northern borders disunited. (“May the tribes ever retain, if not love for us, at least hatred for each other,” as Tacitus put it.) Their leaders could be offered gifts of money, or special protection against their rivals. The sons of chieftains could be brought up within the imperial court and then sent back as “Romans” keen to maintain contact with the empire. “Germans” could serve in the Roman armies as mercenaries. There was thus a surprising amount of contact across the borders, as Roman merchants travelled among the neighbouring peoples and Roman money or support was used by local rulers to build their own prestige. However, a growing awareness of the riches of the empire was unsettling, especially as the population of the German tribes appears to have been growing in these centuries and their resources became increasingly stretched. Tensions between tribes caused shifting coalitions, some temporary, some forged by charismatic leaders into something more coherent and long-lasting. Peoples amalgamated. So there emerged on the central part of the German border in the early third century A.D. a loose confederation known as the Alamanni (“all the men”), and then to the north another people known as the Franks. On the Danube border a merging of migratory peoples with the local inhabitants of the Black Sea area produced the Goths. In their struggles with another tribe, the Sarmatians, a nomadic people from Asia, the latter were pushed towards the Roman border. None of these peoples could prevail in a direct confrontation with a Roman legion, but raids over the border caused considerable disruption. The problem for the Romans was that the barbarians could never be successfully and definitively defeated, as there was no way of controlling so many rival groups whose leaders depended on the prestige of war and the plunder of raids. The Romans tried everything—buying off tribes, stationing legions across the border so that raiders could be dealt with before they reached the frontier, using one tribe against another. None of these tactics brought lasting stability, and by the third century a new wave of raids began. 2
It was unfortunate that these raids coincided with the emergence of a powerful new state in the east, that of the Sassanids. Its predecessor, the Parthian empire, had often been at war with Rome, but the campaigns of the 160s and the 190s had been successful. In 197, the emperor Septimius Severus had even sacked the Parthian capital, Ctesiphon, and extended the empire as far as the Tigris. The defeats were evidence of the decline of the Parthian empire after some 400 years of success, and in the 220s the Parthians finally succumbed to the Sassanids, a fiercely nationalistic people who claimed to be reviving the glories of the Achaemenids (the Persian empire that had been overthrown by Alexander). Under Shapur I (who ruled 239–70) the Sassanids claimed the ancient borders of the Achaemenid empire, the western of which were, by now, deep in Roman territory.
So began the so-called crisis of the third century, which saw a series of attacks and border raids by both Sassanids and German tribes over a period of some fifty years (234–84). On the German borders the raids were small in scale; they were nevertheless often humiliating because of both the distance the raiders were able to cover once the frontier had been breached and the major cities that proved vulnerable to the raiders. The Goths reached Ephesus in 253; in 260 the Alamanni assaulted Milan. In 267 Athens was sacked by the Heruli (a people of whom there is no other record), its celebrated Hellenistic stoas destroyed in the onslaught. Some raiders even reached Spain. The Sassanids also had their successes. In 253 or 254 they sacked Antioch, one of the great cities of the eastern empire, and in 260 they inflicted the most profound humiliation of all, the capture of the emperor Valerian, whom Shapur is said to have used as a footstool from which to mount his horse. The triumph of the Sassanids over the Romans was celebrated throughout the Sassanid empire on rock reliefs in which the humbled Roman generals are shown pleading with Shapur for their release.
The defeats either caused or coincided with a rapid turnover of emperors. Eighteen are known in these fifty years, with average reigns of under three years. The emperor’s authority was heavily dependent on victory in battle; on several occasions defeated emperors were killed by their own men. On the other hand, several victorious generals were to be tempted to declare themselves emperor, turning the Roman armies against each other just at a time when unity was most necessary. Not all the emperors of this period were military failures. Gallienus (260–68) and Claudius II (268–70) had great victories; Claudius’ triumph over the Goths was to become legendary (and was later to be exploited by Constantine for his own ends). Aurelian (270–75) defeated the Alamanni and left a permanent mark on Rome by constructing a vast wall around the city, much of which still stands. Unsurprisingly, the building of walls now became a central preoccupation for cities, and other building projects faltered as a result. There is not a single dedicatory inscription at Olympia dating from after 265. Some emperors proposed innovatory solutions to the crisis, suggesting that the empire’s defence be shared among several emperors ruling concurrently, or the creation of cavalry forces that could respond to raids more rapidly than the infantry legions.
By the 280s, however, stability seemed no closer. Aurelian and his successor Probus were both killed by their own men. Their successor Carus launched a successful invasion of Persia but died while campaigning. His son Numerian, who was with him, was declared emperor of the east, but was found dead in his litter while the army was returning home. His supposed murderer, the praetorian prefect Aper, was himself killed in front of the army by Diocles, one of his senior officers. Diocles then defeated Carus’ other son, Carinus, and in 284 declared himself sole emperor with the name Diocletian. Remarkably, he was still in power twenty years later, presiding over a settled and reinvigorated empire.3
Diocletian, like many of the most successful soldiers of the period, was from the Balkans. His background was humble; he may even have been a freed slave or the son of one, and his rise to power showed how much talent counted in these difficult times. Diocletian was tough, an effective general, but an even more remarkable organizer and statesman. He had both the vision to appreciate the necessity for a major reorganization of the empire and the skills to effect it. His achievement was staggering. To enable the empire to respond to attack more swiftly and buttress the stability of the imperial office, he appointed a deputy, Maximian, a fellow commander from the Balkans, as co-emperor with the title of Augustus. Then he appointed two junior “Caesars,” Galerius and Constantius, the intention being that they should succeed the Augusti when either died (the system is known as the Tetrarchy, “a rule in four divisions”). Meanwhile, each of the four was to play an active role in defending the empire. Constantius was sent to the west, to Britain and Gaul; Maximian presided over Italy and the African provinces; Galerius was in charge of the Danube, while Diocletian remained in the east (although Galerius was later to assume command there). Under the Tetrarchy, Rome began to fight back, gradually consolidating its borders. In 297 Galerius’ defeat of the Sassanids resulted in a decades-long peace on the eastern border.
These victories allowed resources to be released for long-term defence, and a programme of border fortification began. New forts were built, walls and barriers were strengthened and gateways narrowed, enabling them to be held more easily. The army, now some 400,000 strong, appears to have been divided into smaller units to allow it to respond more rapidly to attacks. To finance these developments Diocletian divided the empire into smaller provinces, depriving their governors of their traditional combined role of commander and tax collector. Henceforth in each province a civilian governor concentrated on collecting taxes while a military leader (dux ) was responsible for defence. To increase the efficiency of the tax system, land was assessed according to its productivity and a fixed sum (reviewed every five years) was levied on it. For the first time it was possible for there to be an imperial budget and even some elementary long-term planning. Diocletian tackled the debilitating inflation (arising from the frequent debasing of the coinage) that had accompanied the crisis by introducing a standard gold coin, but when inflation continued (probably as a result of the large numbers of bronze coins still being minted) he attempted an empire-wide Edict of Prices (A.D. 301), which set out an approved price for every kind of produce and fixed rates for each kind of professional service. (A shipwright working on a seagoing ship was to be paid sixty denarii a day, teachers of Greek and geometry 200 denarii per pupil per month, a bathhouse attendant two denarii per bather.) It was far too ambitious an undertaking for a still undeveloped economy and, as socialist-planned economies showed 2,000 years later, only encouraged black-market activity. Despite severe penalties for evasion, the edict became moribund, but it remains a fascinating record of an assessment of comparative values of goods and activities in the empire and, of course, a symbol of Diocletian’s determination.
The third century saw emperors increasingly distance themselves from their subjects. No longer could an emperor be accosted by an old woman, as Hadrian had been 150 years earlier. The figure of the emperor now emerged as a stage-managed presence, addressed not by name but by abstractions—Your Majesty, Your Serenity. Supplicants had to prostrate themselves and kiss the emperor’s robes before making their petitions. These were frequently conveyed to the emperor and then relayed back through a series of officials so as to preserve his inaccessibility. Emperors dressed in purple, a dye so rare that 1,200 murex shells yielded only 1.6 grams of it. (The Edict of Prices valued purple-dyed wool as equal to its weight in gold, 50,000 denarii a pound.) The emperors displayed themselves in great audience halls; that used by Constantius in the northern border city of Trier still survives, though it has long been stripped of its mosaics and marble wall veneers.
The distancing saw the emperor linked ever more closely with the gods. The panegyrics, the speeches of praise offered to an emperor on formal occasions, proclaimed that the very fact that Diocletian had come to power confirmed that he was favoured by the gods, a much more explicit recognition of his semi-divine status than had been customary. (The term used to refer to the emperor’s adoption by the gods was consecratio, “a making sacred.”) Diocletian claimed a particular affinity with Zeus, while Maximian preferred Hercules, who had long been associated with commanders, including Alexander the Great. This was a significant development in the ideology of imperialism because it suggested that it was divine favour rather than either human support (of the army or Senate, for instance) or descent that provided the emperor with legitimacy. The emperor was divine by virtue of his successful accession. In the arch of Galerius in Thessalonika, built when Diocletian and Maximian were still alive, they are shown enthroned above the earth and sky.4 Perhaps this marks the moment when the Hellenistic concept of kingship, initiated by Alexander, had been fully absorbed by imperial Rome. The monarch is removed and imbued with mystery— no longer would an emperor lower himself to engage in debate with philosophers. Imperial authority is clothed with a divine aura.5
In contrast to Alexander, this did not involve the neglect of administration. If there was a theme to Diocletian’s programme it was to centralize the state so that it could function more coherently and effectively. He built on earlier developments. In 212, for instance, all subjects of the empire except slaves had been made Roman citizens so all could be taxed equally. Diocletian took this further by stressing that a common citizenship meant accepting common responsibility for the state, and so those whose allegiances were questionable suddenly found themselves more vulnerable. Prominent among these were the Christians, who, through their resolute rejection of paganism, found themselves in open defiance of the state, “the whore of Babylon,” and its traditional gods, and thus were unable to take part in any public ceremonies or sacrifices. The Christians were well organized, with a clear structure of authority (the bishops); an evolving theology based on worship of the Christian God, drawn from the God of Judaism, and a “saviour,” Jesus Christ, who was believed to have been some form of manifestation (exactly what kind of manifestation remained vigorously disputed) of God in human form; its own calendar, which evolved around its own feast days; initiation rites that distinguished believers from non-believers; and, like the schools of philosophy, its own ethical demands. In the unsettled conditions of the third century, Christians provided secure communities, and even army officers and state officials were now converting. Some of the eastern cities may have had a Christian majority by 300.
The state had always been uneasy about Christians. They posed the classic political dilemma: how far can one show tolerance to a group that itself condemns the tolerance of the state in allowing pagan worship to continue? Christians did not deny the existence of the pagan gods, but they saw them as demons and believed pagans would suffer eternal punishment after death. Up to the third century, persecution of Christians had been erratic, dependent on the whim of individual provincial governors; the crisis of the third century induced the first empire-wide persecution, under the emperor Decius in 250–51, during which bishops in particular were a target. (It has been argued, none the less, that Decius’ objective, as outlined in his edict, was the restoration of traditional cults rather than the persecution of Christians per se.) 6 It remained possible for Christianity to survive; persecutions waxed and waned, and in practice the desperate need for talent in the army and the administration allowed Christians to remain in prominent positions. In many cases a senior official or soldier was dismissed or executed only after every possible means of making him offer a token sacrifice to the state had been tried. By the fourth century, however, Diocletian had to face up to the logic of his centralizing reforms: a large community that refused to show any allegiance to the gods of the empire could no longer be tolerated. Yet Diocletian was a shrewd politician. He was reluctant to become involved in a politically unwinnable campaign against a determined minority. Although in previous persecutions many Christians had capitulated, others had resisted to the point of martyrdom, willingly accepting their reward in heaven in preference to a life stuck in the misery of the material world. Jesus and several of his immediate followers, including Peter and Paul, had died at the hands of the state, so one might say that the readiness to suffer martyrdom was intrinsic to Christian commitment. While Galerius, who had much of the fanatic about him, wished to launch a devastating persecution, Diocletian was more cautious. He consulted widely and even sent to the oracle at Didyma on the coast of Asia Minor for advice.
When Diocletian finally decided to move against the Christians, his actions were marked by their restraint. His first edict (303) was directed at Christian property—buildings, texts, sacred vessels—rather than Christians themselves. Many bishops ordered their congregations to give up property, believing the faith would survive without it, but other congregations, notably in north Africa, refused to surrender anything and condemned those who had. So the persecutions led to a major and enduring schism. As tensions rose, any chance of compromise with the authorities receded. A fire in Diocletian’s palace at Nicomedia was blamed on Christians, and uprisings in the east were also seen as Christian in inspiration. Diocletian might still have held back, but his own health was deteriorating and power was shifting towards Galerius (who was to become Augustus in the east when Diocletian abdicated in May 305). New decrees now demanded that all Christian clergy be imprisoned until they were prepared to sacrifice to the gods of the state and then, in April 304, that all Christians should be required to sacrifice on penalty of death.
Subsequent events depended on the vigour of the local emperors and their governors. In the west Constantius used persecution very sparingly, concentrating only on property belonging to Christians, while in the east Galerius was able to unleash his hatred for Christians. In some provinces the legal process broke down completely as Christians were rounded up, tortured and executed, although even in the east, other governors were able to deflect the legislation, claiming that all local Christians had sacrificed. One way of sidestepping the edicts was simply to ask Christians to affirm the existence of a supreme deity and not require any confirmation as to whether this was Zeus or the Christian God. There is evidence that in Alexandria many Christians were sheltered by pagans.
The impetus behind the orgy of bloodletting soon faltered, and by 310 persecution had become haphazard and without fervour. Galerius was desperately ill with bowel cancer. The Christian writer Lactantius revelled in describing the symptoms that God had sent him in punishment for the persecution he had instigated: “His bowels came out, his whole anus putrefied . . . the stench filled not just the palace but the whole city . . . his body, in intolerable tortures, dissolved into one mass of corruption.” He died in 311. 7 Christianity survived. While the stress of persecution had divided Christian against Christian, the faith itself had proved highly resilient in the face of oppression.
Christianity and the new authoritarian empire of Diocletian were clearly incompatible, but there was an alternative to destructive and debilitating persecutions, and that was to absorb the religion within the authoritarian structure of the state, thus defusing it as a threat. Whatever his motives, personal or political, in first tolerating and then supporting Christianity, this was to be the achievement of Constantine. Before exploring his transformation of Christianity, however, we must make some attempt to understand how this religion, which had been a response to the execution of an apparent enemy of the empire by one of its provincial governors, had survived at all.8