Arguably the biggest challenge facing the Roman empire in the third century was the internal tension caused by the inability of the emperors of the time to win the support of the traditional ruling senatorial class and the increasingly powerful army. The secure hereditary succession of adopted sons in the Antonine period was destroyed as a long line of emperors met their end at the hands of their own troops when faced with the threat of battle against stronger opposing empirical candidates. In 222 the unpopular Elagabulus was murdered by mutinying troops in favour of Alexander, who was in turn murdered himself on order of his opponent for the purple, Maximinius in 235. In the years 235 to 284 the average reign of Roman emperors lasted just 3 years, the vast majority of these short lived rulers meeting a violent end. Aurelius Victor, writing in the fourth century, attributed this to the fact that the Roman army was made up of the “sort of men who are very greedy for money and loyal and true solely for profit”, suggesting that an emperor who failed to placate the army would not last long. The historical record shows however that it could be equally perilous to ignore the wishes of senatorial class. In 238 for example the senate backed the claims of rebels in Thysdrus, Gordian I and II, to the position of emperor, and after their murders the senators M. Clodius Pupienus Maximus and D. Caelius Calvinus Balbinus in opposition to the emperor Maximinius. It was not until 284 that Diocletian managed to bring substantial stability to the empirical office and even he in the words of Drinkwater had won power by the narrowest of margins from Carus, Numerian and Carinus.
Regarding the problems surrounding empirical succession it would appear that those who strove to gain the support of the senate fell foul of the army and vice versa. This points to another serious internal challenge the Roman empire was forced to face in the third century – the shift in the power balance between the senatorial class and the military. Traditionally positions of power in the empire had been concentrated in the hands of the senatorial class; they not only held the top civilian ranks they also served as governors in the provinces commanding military forces. This relationship underwent a transition in the third century; Septimius Severus, sensing the senate was not as amenable as he would have liked strove to win over the army, allowing them to marry during their military service and increasing their pay for the first time since Domitian (81-96). This set a precedent for the rest of the century as emperors came to realise that it was the brute force of the military that would get them into power and, more importantly, keep them there. In the early 250s Gallus began the process of replacing the senatorial governors with men from the equestrian ranks, who had the advantage of having the necessary military experience to command the troops serving under them. In stark contrast to earlier times between 268 and 283 only one emperor, Tacitus, was a senator in emperor. By the time of Diocletian those in power in the provinces were men who, like the emperor himself, had worked their way up through the military ranks from undistinguished backgrounds. The military in turn recognised their newfound position of power and, as Aurelius Victor complained, used it to their best advantage terrorising people in the localities. Successive emperors failed to reign in the army, despite their best efforts – some contemporaries claimed that the assassination of Aurelian in 27 was the result of his emphasis on discipline within the ranks. Whilst this shift in power may have been a bitter pill for the senatorial classes to swallow, and indeed must have caused considerable political tension, the situation was really beyond the control of the civilian senatorial class. The army as now the major source of power within the empire, it just needed to be constrained through the strict discipline of emperors like Aurelian and Diocletian.
Many historians have argued that a major cause of tension within the empire at this time was religion, in particular the sporadic persecution of the Christian minority. These included 249-51 persecution of Christianity under Decius and the persecution by Diocletian whom Eusebius claimed “had been plotting secretly” against the church for years before he became emperor. Religious tensions then were stirred up by emperors in a society that was, in less stressful times, inclined to tolerance towards religious cults. Emperors hoped to scapegoat religious minorities and so increase their own support – this move was never wholly successful however. Although it enabled emperors to appropriate the wealth of high standing Christians encouraging religious intolerance led to disorder and rioting, something that Diocletian and his predecessors could not have wanted. Where this policy was successful was in drumming up support from the traditionalist senatorial classes by stressing the importance of the Roman pantheon.
A more substantial threat to the structure of the Roman empire during the third century was the inflation that accompanied its instability. As successive emperors were forced to debase the silver denarii to pay the troops the currency became increasingly worthless. Under Marcus Aurelius (161-180) the silver content of the denarius had been 75%, by the mid third century that had fallen to just 5%. As Heichelheim points out, every emperor from Augutus faced at least some deficits but the situation in the third century was especially testing. An example from Egypt demonstrates the situation clearly: in the late second century an artaba of grain cost 7 or 8 drachmae, by the time of Diocletian it cost 20 talents – the equivalent of 120,000 drachmae. To pay for the defence of the empire increasingly heavy taxes were enforced. Lactantius argues that Diocletian’s general census was a source of “general misery” as the accompanying tax pushed the common people to their limits. Despite their best efforts the inflation continued, Aurelian made a serious attempt at fiscal reform in the 1270s; the first was disasterous and led to serious rioting at the Roman mint, the second involved recalling the old debased coinage and exchanging it for newly issued silver coinage, but had little impact on the situation. Diocletian decided to overhaul the system completely. In December 301 Diocletian issued an edict on maximum prices, whilst this did not solve the fiscal problems of the empire it shows an increasing willingness to legislate on economic concerns. There could be no quick fix for the problem however, debasement of the nummus and danrius continued even after Constantine introduced a new gold solidus in 307. These fiscal problems faced by the empire meant that the good quality silver coins minted by Carausicus, the unacknowledged British emperor was a cause of embarrassment to Diocletian in the early years of his reign.
Carausicus was not the only pretender threatening to split the empire. By 260 there was a tripartite political division with the emperor in Rome struggling for supremacy against pretenders in Gaul and Palmyra. In the 260s Zenobia had put her young son Vaballathuson the throne under her regency. Initially Zenobia did not push her claim too far, for example, but in 272 after her armies had conquered Egypt the coins start to depict Vaballathuson as Augustus. The solution to this problem was begun under Gallienus and Carus who created permanent field armies. Their mobility allowed important centres of administration to be set up away from Rome, for example in the cities like Trier, Milan and Antioch. Frontier areas that were too difficult to defend, or were simply not worth defending were abandoned; in 271 for example Aurelian ordered the complete withdrawl of all the legionary forces stationed in Dacia. Diocletian split the provinces into smaller territories which were grouped into 12 larger units, or dioceses, for administration purposes. These smaller areas were easier to govern effectively. In addition the establishment of first the diarchy and then the tetrarchy from 293 allowed the empirical government to supervise the provinces more closely, and so gain greater security.
These internal divisions both exacerbated and were caused by the serious external threats to the third century Roman empire. Potter argues that the main cause of the so called crisis was the rise of the Sasanians in Persia. In 244 Philip paid Shapur, the Persian ruler, the huge sum of 500,000 gold dinars and let Persia retain control of Armenia in exchange for a temporary truce, clearly Persia was a formidable foe in the eyes of the empire. In 252 Antioch fell to Shapur. Hostilities had reopened by 245 however and the Persians continued to create problems throughout the 240s and 250s. In 260 Shapur even managed to seize the emperor Valerian alive. Whilst Potter’s conclusions may be somewhat overstated Persia certainly caused the empire anxiety especially as it was simultaneously faced with raids along the Danube and Rhine frontiers from Germanic tribes. Raids by Goths on the Danube caused considerable destruction until Claudius defeated them at Naissus essentially silencing them for the rest of the century in 269. In 271 Aurelian defeated the Vandals then allied with them to push back the Alamanni and the Iuthungi but raids continued elsewhere along the frontier. Some of the difficulties in protecting against foreign invasion were solved by Gallienus and Carus who created permanent mobile field armies and cavalry units. This meant that field armies were no longer made up of men from the frontiers, leaving essential borders vulnerable. Aurelian further strengthened the army, for example by recruiting 2000 horsemen from Rome’s former enemy the Vandals. He also made strategic moves, for example building a wall around Rome which would make the city easier to defend in the event of attack. Diocletian continued this move and increased the size of the army, by 305 the 33 army legions had been increased to at least 67, something that was continued by Constantine. Most of The emperors of the third century committed themselves to protecting the empire but faced with the more pressing task of staying power and preventing domestic disintegration it is understandable that they failed in parts. Without a strong grip on the army and the provinces any success was precarious as whilst the emperor was on one front there might be an attack elsewhere. Lactantius claims that Diocletian’s tetrarchy was unworkable and his splitting of the provinces just created much misery, but it was this that allowed the close supervision of the localities that was needed to restore stability. When Constantine emerged victorious in 306 it was the changes Diocletian had implemented that allowed his sole rule.
In terms of how successful the Roman emperors were in dealing with the challenges of the third century it is unfair to judge all the emperors of the period by the same standards. Some emperors, like Alexander, were fortunate and had a relatively peaceful reign where as others struggled to fight off invaders on every frontier as well as protecting their position domestically. A mark of the success of a usurping ruler is their ability to actually retain power. In this few of the third century emperors were successful, only a handful of over 30 individuals given the title emperor in this period escaped a violent death. Contemporaries singled out, amongst others Aurelian and Diocletian, as emperors worthy of praise, although it is interesting that this opinion was not shared by all. Lactantius, a Christian writer, claimed that Diocletian, far from being a great emperor was “an author of crimes and a deviser of evils.” Rostovtzeff argued that Diocletian was no better than any other third century emperor, it was just that the situation in the empire had become so desperate that the rule of any strong leader would have been accepted. Such a view is misleading, a strong leader may well have gained power but it took Diocletian’s management skills to retain that power.
In conclusion the Roman empire faced a variety of internal and external challenges during the third century, these included an unstable line of succession, tension between the traditional ruling class and the increasing power and status of the army, religious tension, inflation, and external invasion threats. Fundamentally the third century emperors dealt with the challenges successfully as the empire survived into the fourth century in a unified form. However as Tainter points out, the price had been high. The empire that emerged in the fourth century was substantially different to the empire that had existed at the start of the third century. There had been a shift in the source of the ruling classes from the Italian senatorial class to the ranks of the military, and inflation had resulted in huge fiscal changes and a return to the feudal method of paying in kind in some areas. Whilst the vast majority of third century emperors had been unsuccessful, failing in the face of the massive challenge before them, a few, like Aurelian and Diocletian, succeeded in laying the framework for short term security although more needed to be done, especially in terms of securing the frontiers and resolving the problem of inflation.
- Lactantius De Mortibus Persecutorum ed./tr. J.L. Creed (1984)
- Eusebius Church History VIII -Aurelius Victor de Caesaribus tr. H.W. Bird (1994)
- Eutropius Breviarium tr. H.W. Bird (1993)
- The Canonical Letter of Gregory Thaumaturgus and Sintana de Murescernjachov culture in The Goths in the Fourth Century. Peter Heather and John Matthews (1991)
- Chapters 1-6d in The Cambridge Ancient History – second edition – volume XII – The Crisis of Empire AD 193-337. A. Bowman, P. Garnsey, and Av. Cameron. (2005)
- Chapters 1 and 2 in The Later Roman Empire. A.H.M. Jones (1964)
- Chapters 1 and 2 in The World of Later Antiquity. Peter Brown (1970)
- Chapter 1 in A History of Byzantine State and Society. (1993)
- Diocletian and the Roman Recovery. (to page 150) S. Williams (1985)
- pp. 128-52 The Collapse of Complex Societies. J.A. Tainter (1988)
- pp.18-64 Prophecy and History in the Crisis of the Roman Empire: A Historical Commentary on the Thirteenth Sibylline Oracle. D.S. Potter (1990)
- Chapters 10-11 in The Social and Economic History of the Roman Empire – revised edition. M. Rostovtzeff (1957)
- Pp. 358-77 The Third-Century Crisis and the Greek Elite in the Roman Empire. L. de Blois, Historia 33 (1984)
- Aurelian and the Third Century. A. Watson (1999)
- Chapters 1-5, 13, 14, 17 in The Roman Empire and its Neighbours. F. Millar (1966)