Expansion and upheaval

Chris Gray continues his series on the Roman empire with an examination of the period 31BCE-284CE

Although Julius Caesar showed the way forward, the real founder (courtesy of Brutus and Cassius) of the Roman empire was Caesar’s great nephew and adopted son, C Octavianus, better known first as Octavian1 and then (by senatorial acclaim in 27BCE) as Augustus.

As Caesar’s chief heir, Octavius had influence with the legions, and Cicero and the senatorials hoped to use him against Marcus Antonius, making him a senator and giving him a proconsular command in support of the consuls Hirtius and Pansa. The consular army succeeded in defeating Antonius, but both the consuls died, leaving Octavius in command of a force of eight legions. At this point the senatorials seem to have thought that the ‘boy’ had served his usefulness and could be dispensed with. Octavius lost no time in disabusing them of this idea: he marched on Rome and demanded to be elected consul; the demand was acceded to.

Any attempt to trace in detail the steps by which Octavian succeeded in gaining control over the whole Roman world cannot be made here, for reasons of space. We concentrate instead on the creation of the formal empire, or ‘principate’, as it is known (since Augustus wished to be known as princeps2 or ‘first citizen’) and on Augustus’s political and economic policies.

The principate

Augustus’s power derived from control of the legions, but in order to run the empire he needed the support of the Senate, which was a valuable source of administrators, such as provincial governors. Consequently Augustus was forced to disguise his power in constitutional forms, and to search for precedents in various powers existing under the republican constitution. After a period of experimentation he finally hit on the two precedents which, in combination, gave him the necessary constitutional powers.

The first of these was the tribune’s power, the tribunicia potestas, which gave him the right to veto laws and actions of other magistrates. The difficulty here was that a tribune did not have power outside the city boundaries. Consequently Augustus was careful to acquire a proconsular imperium maius in 23BCE, which gave him overall control of the armies and provinces - he could direct any single provincial governor if necessary. The model for this power was the command against the pirates given to Pompeius in 67BCE: since it was necessary to clear the whole Mediterranean of pirates Pompeius was authorised to instruct any provincial governor to take whatever measures he saw fit. Augustus acquired one or two other powers, including the right to make treaties, but the tribunicia potestas and the imperium maius were the basis of his legitimacy.

Additionally Augustus needed to take steps to conciliate the Senate in an explicit fashion. Having already seen to it that the Senate was composed of people willing to support him,3 Augustus prepared to turn it into a virtually closed corporation by establishing a formal property qualification of one million sesterces for potential members. He also made membership of the senatorial class hereditary4 with additional requirements of a necessary period of military service and “personal integrity”. In short, a senatorial career depended on being persona grata with the emperor, who could, if he saw fit, create senators as required, by special dispensation. But Augustus was anxious to conciliate the existing Senate, giving its members control over a number of provinces (not the most politically sensitive ones) and granting them the right to attend banquets at public expense.5

Augustus’s need to work closely with the Senate helps to explain the contrast between the political tendency of his legislation and that of his illustrious uncle, Julius. Caesar’s ambitious plans for draining the Fucine Lake and the Pontine Marshes were abandoned, likewise his projected canal linking Rome with its ports of Ostia and Puteoli. Augustus reversed his uncle’s policy of publishing the proceedings of the Senate, and the popular assembly was reduced to a mere rubber-stamp body.

He avoided any measures designed to ease the burden of debt or distribute land to those who wanted it, except where his veterans were concerned - the poet Virgil had to make a special appeal to him to be allowed to retain possession of a farm which had been allocated to some ex-legionaries.6 His taxation policies were not notably progressive; virtually the sole measure of his which could be called such was his distribution of 1,000 sesterces per child to those Roman citizens “of the plebs” resident in the capital who could claim legitimate sons or daughters - a sort of limited family allowance.7

Above all, Augustus imposed restrictions on the manumission of slaves via the Lex Fufia Caninia (2BCE) and the Lex Aelia Sentia (4CE): the concern here presumably was to maintain as far as possible the numbers in the slave labour force.8 Thus, whereas Julius had deliberately encouraged the popular masses in order to win popularity, Augustus was concerned to protect the status quo. The modern parallel here is with fascism, which shows a left face as it seeks to gain control, only to reveal its counterrevolutionary essence once in power.

It was clearly Augustus’s intention to found a dynasty; accordingly, he began grooming his grandsons, Gaius and Lucius Caesar, to succeed him, but they both died, and Augustus was forced to fall back on Tiberius, his stepson,9 who at least, as a successful general, was popular with the legions. The Senate could be relied upon to acquiesce in his choice of successor. Hence the Julio-Claudian line of emperors duly appeared, and Augustus’s heirs ruled from 14 to 68CE.

As with all hereditary rulers, there were occasional succession problems. It was difficult to remove unsatisfactory emperors, as demonstrated by the examples of Caligula and Nero. The former was removed by a coup d’etat carried out in Rome, which led, via the intervention of the imperial praetorian guard, to the elevation of Claudius; Nero’s conduct eventually sparked off a provincial revolt, and once again the Praetorian Guard intervened, to overthrow Nero, whereupon the Senate seized the opportunity to elevate Galba.

The latter was not a hit with the soldiers, who proceeded to demonstrate collectively that it was only possible in practice for an emperor to rule if he could command the support of the troops. The difficulty was, of course, that the troops were often divided as to who they wanted in the job, and ultimately the only way such disagreements could be resolved was by force of arms - a messy business all round.

Expansion of the empire

Having disposed of his own rivals for the support of the legions, Augustus continued with the expansionist dynamic of the Roman commonwealth, which had been in progress since the mid-3rd century BCE. He began the final phase of the reduction of Spain (completed by Agrippa in 19BCE) and of the Alpine areas likewise, establishing the imperial frontier along the whole length of the Danube. Galatia was annexed as a Roman province on the death of its pro-Roman king, Amyntas, in 25BCE. The eastern frontier was stabilised, with the recovery of the Roman standards captured by the Parthians at the battle of Carrhae in 53BCE. Herod ruled Judaea as a Roman protectorate; he died in 4BCE, and the subsequent settlement proved unsatisfactory, so Judaea was established as a Roman province in 6CE. An expedition was launched against the Sabaean kingdom, which controlled the strait at the southern end of the Red Sea, the modern Bab-el-Mandeb. The Egyptian frontier was pushed as far south as it would go.

A determined attempt was made to extend Roman control over the Germans. This was part of a grand design aimed at achieving a shorter northern frontier by advancing as far as the Albis (river Elbe) and incorporating today’s Czech lands, which had been occupied formerly by the Celtic Boii - whence the name Bohemia - before being overrun by the Marcomanni (the ‘men of the Mark’) under their king, Maroboduus. The latter became the target of a pincer movement in 6CE involving no less than 12 legions, with one force attacking from the west and another, under Tiberius, from the south-east.

The project was fatally disrupted by a major revolt in the province of Pannonia and Illyricum, which Tiberius could only crush after three years’ hard fighting. Then in the year 9 of the christian era there occurred the annihilation of three Roman legions under Quinctilius Varus by the Cherusci in the Teutoberger Wald, which left Augustus badly shaken: Suetonius reports him as exclaiming often “Vare, Vare, legiones redde!” - “Varus, Varus, give me back my legions!”

In spite of this policy of rounding off the imperial frontiers, Augustus succeeded in reducing the number of legions in the field in 9CE to 2810 - no mean administrative feat. It may have been the disaster in Germany which prompted him to advise the Senate as part of his ‘testament’, so to speak, not to extend the empire any further, since that would make its frontiers more difficult to guard and there would be a risk of losing what had been gained.11

Further extensions

The Roman emperors were, it seems, sorely tempted to disregard Augustus’s advice, and quite a few of them chose to do so. One of these was Claudius, who resumed the ‘rounding off’ policy, founding two provinces in Mauretania, where he inherited a conflict from Caligula’s reign, and establishing two more in Thrace and Lycia (Asia Minor).

But his principal extension of the empire was his invasion of Britain in 43CE. Strabo, in his Geography, expressed the opinion that there was no need for any occupation of Britain because the native rulers were so friendly that they were willing to acquiesce in the imposition of significant duties on their exports to the empire, whereas, if an occupation force was to be sent in, the expense of its upkeep would offset any appreciable tribute, and it would be necessary to reduce the export duties as well.

Claudius and his advisers nonetheless thought that a military expedition would be worth the effort, in view of Claudius’s scholarly background (he was only made emperor because he was discovered hiding behind a curtain on the death of Nero) - he believed a military victory would be very useful for propaganda purposes.

Strabo was right about the costs, but there were some additional benefits. These came in the form of supplies of silver and lead - silver for the currency, lead for glazing pottery and making glass.12 Even so the Romans nearly lost control of the whole island on the occasion of Boudicca’s revolt and had to keep three legions there to make sure they held onto it.

The next virtually irresistible temptation to make a major extension to the empire occurred in the reign of Marcus Ulpius Traianus (Trajan) in 98CE. But in order to appreciate the circumstances here we have to go back to the principate of Titus Flavius Domitianus (Domitian): ie, the period 81-96CE. This reign is remarkable for the presence of three factors which recur in the chronicle of the empire’s decline - barbarian pressure, a military revolt and straitened state finances. Suetonius neatly combines these in the following judgement on the emperor:

“Reduced to financial straits by the cost of his buildings and shows, as well as by the additions which he had made to the pay of the soldiers, he tried to lighten the military expenses by diminishing the number of his troops; but, perceiving that in this way he exposed himself to the attacks of the barbarians, and nevertheless had difficulty in easing his burdens, he had no hesitation in resorting to every sort of robbery. The property of the living and the dead was seized everywhere on any charge brought by any accuser.”13

It may be the case, of course, that the connection between the factors was not quite as Suetonius alleges, but it was certainly present. The problem in foreign policy was principally the rise of Dacia under Decebalus: in 85CE Decebalus’s forces crossed the Danube and killed the local Roman governor. Domitianus was determined to avenge this, but the force he sent to do the job was soundly defeated, with the loss of one whole legion (V Alaudae). Eventually the emperor and Decebalus reached an agreement whereby Dacia formally became a Roman protectorate but was accorded a subsidy (renewable) from the imperial treasury, plus “artisans of every trade pertaining to war and peace”.14 The Roman government only agreed because it had to deal with additional threats from other trans-Danubian peoples.15

Titus Flavius Domitianus was killed in a palace coup in 96CE. His successor, elderly senator M Coccieus Nerva, solved the succession problem by adopting as his son M Ulpius Traianus, who was a military man. Decebalus now had a more formidable adversary to contend with.

According to Terry Jones and Alan Ereira in the book which they wrote (with expert assistance) to accompany Terry Jones’s BBC TV series Barbarians, Roman imperial finances badly needed reinvigorating at this point - which certainly ties in with the information we have from Domitianus’s reign, as noted above. The acquisition of Dacia was the perfect solution because of its gold mines and its generally rich endowment of gold and silver objects. The invasion and conquest of the country, therefore, was a simple act of purloining natural resources - principally the gold and salt mines - involving the expulsion of the current inhabitants:

“The land was swept clean. Survivors fled northwards, while Trajan imported a new population of legionaries, peasants, merchants, artisans and officials from Gaul, Spain and Syria. A new Roman Dacia was built, with new cities, new fortresses and new roads.

“And the Romans set about extracting all the gold and silver they could as fast as they could, and shipping it out of the country on a massive scale. The mines were worked by huge numbers of slaves, whose bodies were heaped in mounds at the end of their short working lives. The Romans stripped Dacia not only of its deposits of precious metals, but also of all the gold and silver objects that they could lay their hands on. And they must have done a thorough job because hardly any gold has since turned up in the archaeological record.

“So prodigious was the amount of booty that Trajan brought back from Dacia that the bottom fell out of the gold market and its price plummeted throughout the empire.”16

It was a resounding solution to the financial problem, but there were strategic drawbacks. A glance at the map shows the frontier of Roman Dacia following the Tisza river (which runs parallel to the southward-flowing section of the Danube) for about half its length in parallel before turning east to include most of northern Transylvania as far as the Carpathians; yet instead of advancing to the river Prut, which forms the modern Romanian border with what is now Moldova, the border follows roughly the line of the Carpathians southwards before running along the river Olt, which joins the Danube several miles before the junction of that great river with the Prut.17

The resulting configuration leaves two significant salients or re-entrants pointing inwards over the Roman frontier: one between the Danube and the Tisza; and the second between the Olt and the Danube. Traianus may have thought it possible to effect a subsequent colonisation of these two areas: it never happened, although Marcus Aurelius did his best to incorporate the first salient at a later date.

Overstretch and the revival of Persia

On Antoninus Pius’s death in 161 Marcus Aurelius and Lucius Aurelius Verus were created joint emperors, Antoninus having adopted them on his predecessor’s orders. They ruled jointly until Verus’s death in 169. Verus repelled a Parthian move against Rome’s client, Armenia, but unfortunately his troops contracted the plague, which spread westwards as a result, with adverse demographic consequences.

Also from around 165 onwards a series of incursions from across the Black Sea and across the Danube began. The Black Sea raiders reached the Aegean and attacked central Greece from there. More seriously, the Marcomanni (Germanic) and the Quadi (Iranian) plus a string of lesser tribes crossed the middle Danube and reached Aquileia at the head of the Adriatic before being driven back. Marcus had to raise two new legions and recruit slaves and gladiators to stop them, auctioning off imperial property and debasing the coinage in order to raise the necessary funds.

He also had to deal with a rebellion by Avidius Cassius, governor of Syria, whose troops proclaimed him emperor. Fortunately Marcus was militarily equal to all these tasks, but he died before he could deal with all the problems posed by his trans-Danubian enemies - including the Iazyges, who invaded Roman Dacia - and on his death his irresponsible son and heir, Commodus, abandoned the work of ironing out the Danube frontier.

There is evidence also at this time that the empire was facing manpower problems, since Marcus felt compelled to settle some conquered Marcomanni within Roman territory with the obligation to provide recruits for the legions.

It is difficult to resist the conclusion that the east exercised a fatal attraction on the Roman emperors in this period. Once he had sorted out the military chaos following the palace coup that got rid of Commodus, the emperor Septimius Severus decided on another Parthian expedition.

Terry Jones and Alan Ereira put the situation bluntly: “The empire was, by this time, an economic basket case. The machine had to keep feeding itself with plunder, and there was no more plunder to be had unless Severus could achieve the kind of victory in Persia that had eluded Rome since the time of Crassus …

“An arch constructed by Severus still stands in Rome today. It was built to illustrate his greatest triumph - when in AD96 he went into Persia and smacked it very, very hard. This absolutely gigantic monument was the first significant architectural addition to the forum since the time of Hadrian, 80 years earlier. It celebrated the fact that he had finally got his hands on the money that Crassus had failed to obtain. He captured Ctesiphon and created two new Roman provinces, called Osrhoene and Mesopotamia, out of the western section of the Parthian empire. And in the process he carried away loot in such quantities that economists reckon it kept the Roman empire out of the red for 20 or 30 years.”18

The Romans then discovered that they had stirred up a hornets’ nest. While Severus’s wife, Julia Domna, and her sister, Julia Maesa, and niece, Julia Mammaea, did their best to hold the Roman empire together behind the scenes through the next four imperial reigns down to 235CE, a new dynasty arose in the Persian territories named after its originator, Sasan - whence ‘Sassanid’; the dynasty’s real founder was Ardashir I (who reigned from 224 to 240CE) - crowned ‘king of kings’ (shahanshah) in Persepolis in 226.

Ardashir reunified the Persian empire, gave its core a new name - Iran, country of the Aryana (Aryans) - and embarked on a project for giving the Romans a dose of their own medicine by invading their Mesopotamian province some time between 237 and 240.19 The Sassanid rulers and their armed forces scored several devastating victories, physically disposing of no less than four Roman emperors.20 It took the Roman empire around 60 years to achieve parity - taking Galerius’s victory in 298 as the date of that achievement.

The Sassanids created a new revived superpower to the east of Roman territory, possessing irrigation works, a central bureaucracy and a semi-professional army with the potential to rebuild the far-flung empire of such Persian ‘great kings’ as Kurush (Cyrus), Daryavaush (Darius) and Khshayarsha (Xerxes), with its hold on Asia Minor, Syria, Palestine and Egypt.

Military anarchy

The revived Persian menace played a big part in the emergence of a period of prolonged upheaval and unrest in Roman dominions which is commonly known as the period of ‘military anarchy’ (roughly 238-284CE). Septimius Severus had already raised the number of legions from 30 to 33 - in the reign of Diocletianus (284-305CE) the number stood at 67.21 In retrospect the question is not so much ‘Why did the Roman empire lose its western territories in the 5th century CE?’ as ‘Why did it not break up in the 3rd?’

But before we come to that we must consider the causes and course of the ‘military anarchy’. To put the question another way, what limits to the empire’s development did the military anarchy lay bare? The reason for this approach is that when a subject approaches barriers or limits qualitative changes are likely to occur (as in this case).

The prosperity of Rome was linked to imperial expansion, and, apart from Claudius’s absorption of part of Britain, Trajan’s similar operation in Dacia and Septimius Severus’s depredations in Mesopotamia, expansion was basically over. The rise of Sassanid Persia now put an end to the extension in the east: more than that, it forced an increase in military expenditure and a frantic search by the imperial authorities to grab additional funds from within the empire, leading to the confiscation of city revenues.22

The appearance of a limit on eastern expansion therefore put pressure on an internal limit - namely the capacity of the economy to provide the surplus necessary to meet the enforced defence requirements. Another adverse effect was an enhanced readiness to debase the currency, causing inflation, and a drive to increase taxation. Likewise, as Peter Heather observes, the empire’s centre of gravity shifted to the east as a result of concentrating on meeting the Persian threat, upsetting the balance between the various armed formations of the empire, all of which had their individual interests:

“As a string of emperors was forced eastwards from the 230s onwards to deal with the Persians, this left the west, and particularly the Rhine frontier region, denuded of an official imperial presence. As a result, too many soldiers and officials dropped out of the loop of patronage distribution, generating severe and long-lasting political turmoil at the top … the 50 years following the murder of emperor Alexander Severus in AD235 saw the reins of Roman power pass through the hands of no fewer than 20 legitimate emperors and a host of usurpers, between them averaging no more than two and a half years in office. Such a flurry of emperors is a telling indication of an underlying structural problem.”23

The result was not only an increase in power struggles between rival imperial claimants but the appearance of a tendency towards separatism in the west - affecting Gaul, Spain and also Britain. The most glaring example of this was the so-called ‘Gallic empire’ (259-274CE). Not surprisingly, the various Germanic and other peoples poised outside the Rhine-Danube frontier were not slow to take advantage of the situation:

“… the imperial defences were breached and the barbarians poured in - free Dacians, Carpi, Goths, Burgundians, Marcomanni, Juthungi - chiefly over the Danube into the Balkans, even into Italy or across the Euxine [Black Sea] into Asia Minor. In 253, 256 and 257 they were in Asia Minor; in 267 burning down the temple of Artemis at Ephesus. Athens fell in 268. In 253 the Alemanni were in the neighbourhood of Rome; in 269 and 270 north Italy was being ravaged. There seemed no limit to the number of such invaders. They were huge, energetic men, vulnerable only in as far as they were badly organised, badly equipped, fighting bare-headed without helmets.”24

Somehow the Romans found the resources, human and material, to weather the storm. The emperor Gallienus, faced with external enemies and a total of 19 rivals, fought them all vigorously, with the exception of Odaenathus and his wife, Zenobia, in Palmyra in the east, with whom it was politic to cooperate against the Persian menace. He was killed by some of his own troops while besieging the pretender Aureolus in Milan. In the course of his reign he banned senators from exercising military commands.

His successor, Claudius Gothicus, disposed of Aureolus and his forces, expelled the Alamanni from Italy and defeated the Goths near Naissus (Nis in Serbia). Aurelianus (270-275CE) began the provision of a new outer wall for the capital, suppressed the Gallic empire and the Palmyra regime ruled now by queen Zenobia, and organised an orderly withdrawal from the exposed Dacian province. Probus (276-282) successfully dealt with a Germanic invasion of Gaul. Finally the Roman forces in the east raised to the purple a former Illyrian shepherd boy called Diocles, better known in this country as Diocletian (Diocletianus).


His origins notwithstanding, Diocletianus was a hardened conservative, but he was prepared to introduce innovations in the system in order to maintain it. Hence, in spite of his instinctive yearning for a return to the status quo, or an intensification of it - irregular taxes in kind should be standardised, prices should be fixed, tenants should be prevented from leaving their ancestral villages, sons should follow their father’s profession - he realised that the empire’s size prevented its successful defence from a single centre.

Accordingly he divided it between himself and Maximianus, with Galerius and Constantius as their deputies; Diocletianus and Maximianus were given the title ‘Augustus’, Galerius and Constantius that of ‘Caesar’. This was the so-called tetrarchy (‘rule of four’).

The scheme was a failure, because it did not address the underlying cause of the fragmentation of power in the empire. Diocletianus’s price-fixing measures were likewise ineffective, but he at least began the restoration of a viable currency: “Diocletian restored the three-metal coinage and issued better-quality pieces.”25

In 305 the emperor retired to his palace on the Adriatic coast. When the resultant turmoil ended, a momentous change took place in the ideological and organisational make-up of the empire - the installation of an avowedly christian regime under Constantine.


1. The Senate in 43 decreed that he could use the name ‘Caesar’, but modern English historians call him Octavian in order to differentiate him from his great uncle Julius.
2. Our word ‘prince’ derives from the Latin princeps.
3. Augustus reduced the number of senators from 1,000 to 800, and then in 18BCE from 80 to 600 (see HH Scullard From the Gracchi to Nero London 1982, pp210, 216).
4. Ibid p224.
5. See J Scheid An introduction to Roman religion Edinburgh 2003, p90.
6. See Eclogues VI and IX, where Alfenus Varus is praised, because it was he, along with Asinius Pollio and Cornelius Gallus, who brought the poet’s case to Augustus’s attention, as Suetonius records in his life of Virgil. See also R Graves, ‘The Virgil cult’ Virginia Quarterly Review Vol XXXVII, 1962.
7. Suetonius Vita Divi Augusti XLVI.
8. HH Scullard From the Gracchi to Nero London 1982, p232 gives the provisions in these laws.
9 See ibid pp217-18.
10. HMD Parker The Roman legions Oxford 1928, pp89-90.
11. Cassius Dio, lvi, 33. See also Tacitus Annals xi, 1; Suetonius Augustus 101.
12. T Jones and A Ereira Terry Jones’ barbarians London 2006, p62.
13. Suetonius Domitianus XII.
14. See T Jones and A Ereira Terry Jones’ barbarians London 2006, pp107-09.
15. “The settlement was forced on Rome by the build-up of heavy pressure on Pannonia to the west of Dacia from Marcomanni, Quadi, Jazyges and Sarmatians north of the Danube. They crossed the river in 92 and, before they were driven back, another legion, XXI Rapax, had been destroyed” (JPVD Balsdon Rome: the story of an empire London 1970, p115).
16. T Jones and A Ereira Terry Jones’ barbarians London 2006, pp112-13.
17. A handy map can be found in M Goodman The Roman world 44BC-AD180 London 1997, p225.
18. T Jones and A Ereira Terry Jones’ barbarians London 2006, pp171-72. See Cassius Dio, lxxvi, 9.
19. The dating is Peter Heather’s in The fall of the Roman empire: a new history Oxford 2006; C Wells The Roman empire, second edition, Harvard 1992 gives 230CE.
20. See P Heather The fall of the Roman empire: a new history Oxford 2006, pp60-62, where some of the gory details are recounted.
21. JPVD Balsdon Rome: the story of an empire London 1970, p225.
22. P Heather The fall of the Roman empire: a new history Oxford 2006, p64.
23. Ibid p66.
24. JPVD Balsdon Rome: the story of an empire London 1970, p203.
25. P Southern The Roman empire from Severus to Constantine London 2001, p160. For more detail see AHM Jones The later Roman empire Oxford 1986, p438.