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An Alternate History of the Roman Empire: Things Fall Apart but the Centre can Hold

By Tim Venning

Macrianus Minor on a coin celebrating Eternal Rome. Image shared under the CC BY-SA 3.0 licence.

This Series of Articles discusses a hypothetical history of the Roman Empire wherein Marcus Aurelius lives longer and so it's more stable. In the first six articles this took us to 260.

With Valerian’s son Gallienus busy fighting in Marcomannia in 260 and unable to intervene in the East , the remnants of the Eastern army retreated to Antioch and as the Persians advanced into Syria headed West into Asia Minor under a junta of senior officers, led by the Macriani (father and son) who ended up securing enough support by looting and distributing the Imperial regional treasury at Antioch to be recognised as Emperors by most of their army. They held out in Cappadocia while Syria was ravaged, but the abandoned Roman garrison in Antioch held out thanks to its huge walls although the upper Euphrates cities and garrisons were evacuated – their local governor refused to abandon his allegiance to Gallienus so the Macriani refused to send him any help .His force then staged a famous and poetically-celebrated ‘fighting retreat’ over the eastern Anatolian plains and mountains to Trapezus, which was hailed as the work of a ‘new Xenophon’ after that Ancient Greek’s military retreat along a nearby route from Mesopotamia to Trapezus in 401 BC, and in Pontus the local Roman garrison and fleet helped them to evacuate by sea to Byzantium in spring 261. Gallienus’ local commander, Probus the future aide to 270s Emperor Aurelian, then used their army to help his men hold back the Macriani in Bithynia in a hard-fought war there in 261-2, which halted the Macriani’s bid to cross from Asia Minor to Europe and led to the ageing elder Macrianus, injured and ailing, abdicating.

His son Macrianus II ruled most of Asia Minor for the moment and lasted until 265, but this was due to the preoccupation of Gallienus’ Balkan commanders Aureolus, Probus and Domitianus with keeping the lower Danube frontier secure – they dared not march East of Bithynia - rather than much local support. The real strongman of the area was the talented, adaptable but ferocious commander the Macriani had left at the Taurus mountain passes S of Cappadocia to hold the Persians back, Callistus (nicknamed ‘Ballista’, ‘the Catapult’), who held up a large Persian army at the hastily-erected defences of the Cilician Gates passes through 262 and then drove t back to the Euphrates in a masterly campaign in 263, freeing Cilicia which the Persians had thoroughly looted.

Resistance to Persia in Syria was led successfully by the local Greco-Arab merchant princeling Odenathus, ruler of the desert trading-city of Palmyra (as in OTL), who came to the rescue of Antioch with his army of fierce desert skirmisher horsemen in 262 and mauled the besiegers so successfully that even the ambitious Shapur had to call off his planned march up the Orontes valley and fight a defensive war to hold onto eastern Syria. Odenathus was then accepted as de facto ‘Princeps et Praefectus’ of the east by the abandoned Roman administrators and generals in Syria, Phoencia and Palestine and used his huge income from local trade and a hired army of Arab tribesmen from the interior of northern Arabia to drive the Persians out of eastern Syria as far as the Euphrates in 263-4, but the Empire’s own troops held onto Egypt and continued to recognise Gallienus as emperor – not least as their commanders needed the goodwill of the authorities in Rome to continue to export Egyptian corn and imported spices from India to the capital. Odenathus auctioned his support to Gallienus and recognised the latter as his nominal sovereign in 263 in return for keeping up sending some Syrian and Mesopotamian taxes and trade to the central Empire by sea, avoiding rebel Asia Minor.

Gallienus, moving to the lower Danube to deal with more Germans (this time the Roxelani) who invaded the region in 264, had to ‘down-grade’ the Rhine army in his list of priorities in order to take a large army East. Securing Dacia and Marcomannia as the generals there put down opportunist military mutinies , he drove the Roxelani out of western Moesia and so made up for the absence of his local commanders Aureolus and Domitianus who were to the South East in Bithynia fighting the younger Macrianus; he thus secured the Balkans for the central government. (In this version of events, there has been no major Gothic attack on Greece or W Asia Minor and Athens has not been sacked; the region’s towns and cities are safe but denuded by plague.) On the Rhine, however, resentment at Gallienus concentrating on Dacia and the lower Danube led to the general who took control in 264 to drive opportunistic German raiders back from the Moguntiacum region, a ‘self-made’ officer with useful local connections called Postumus, capitalising on discontent to lead a successful revolt. The armies of the lower Rhine and later those in Britain accepted him as Emperor, partly because of anger that Gallienus had ordered large numbers of their troops off to the distant Balkans but mostly as the legitimate government was too far away to rescue them if they defied the rebel. Gallienus’ teenage son Saloninus, ‘Caesar’ since 259 and left in technical command at Colonia Agrippinensis (Colonge),was killed and the ‘Gallic Empire’ was created as in OTL, but only in 264 (260 in OTL) and failing to secure Spain which stayed loyal to the government in Rome. Gallienus ruled the centre of the Empire successfully and in 265 drove Postumus back from an attempt to cross the Alps into Italy – but he was still too preoccupied defending the Danube to attempt to reconquer the East. The Roman ‘centre’ Empire was stronger than in OTL, with a larger central army including more Germans from the tribes of Marcomannia, Dacia, and the upper Rhine area (who were fighting for not against Rome at this juncture).

As in OTL, the imaginative Gallienus ‘re-booted’ the Roman army to create a strong and permanent central army commanded by the Emperor and based at his headquarters, which was usually Mediolanum in northern Italy after 265 as it was closer than Rome to the threatened frontiers to the North – and also closer to the rebel areas of the upper Rhine and Gaul should Postumus invade again. Gallienus also created a large new cavalry force, which helped his manoeuvrability in case of sudden military crises, and as well as setting up a large chain of stud-farms in Cisalpine Gaul and Noricum to breed horses for the cavalry he enrolled large numbers of wealthy younger Italian aristocrats , who could provide their own horses, in his cavalry. These young nobles, plus tough and adaptable provincial ‘self-made’ officers promoted by merit (often from the Balkans and Illyria as in OTL), were the centre of a new and largely military circle of influence around the convivial and approachable Emperor – the ‘comites’ (‘counts’), aka ‘Imperial Companions’, with a self-conscious comparison with the equivalent circle that had surrounded Alexander the Great.

This group duly provided both an increasing number of provincial governors, as men trusted by the Emperor unlike scheming senators who might want the throne and also as men able to fight in a crisis, and the centre of the new elite of capable officers who surrounded Gallienus’ successors Claudius II and Aurelian. The suspicious Gallienus, fearing aristocratic plots to overthrow him centred on the old senatorial families, decreased dramatically the number of civilian senators of established families who were given senior posts in the administration and in particular cut down the number of senators made provincial governors – but he did not specifically ban them from these posts (as in OTL) though non-aristocratic ‘equites’ and provincials came to fill most of these posts under him and his successors. There were also senatorial mutterings at Gallienus’ private dabblings in the more esoteric and mystical expressions of Greek philosophy as ‘un-Roman’ and as bad as the ‘Greekling’ Hadrian; he hosted seminars for assorted philosophers of ‘breakaway’ or mainstream Platonist, Stoic, and Epicurean sects at his villas when not on campaign and was particularly close to those mid-C3rd Platonist enthusiasts who were developing a mystical version of Plato’s thoughts into a coherent belief-system enshrining the idea of a ‘Single Deity’ and controlling mastermind of the universe whose purposes could be explored by advanced numerology.

The ‘Neo-Platonists’ lacked a long-recognised supreme deity like the Eastern saviour-cults did, but as interest in the ancient Roman gods – whose cults were more a matter of rigid annual ritual than passionate belief – waned in an era of long-term and multi-faceted crises many intellectuals were turning to more satisfying and exotic religions that provided existential ‘answers’ and mystic explanations for a baffling world. Gallienus was in tune with this and was said to be dismissive of what the traditional cults of the Olympians could offer, and the appeal of Plato’s complex philosophic system of belief - and of his political belief in an elite of ‘philosopher kings’ – to centuries of the well-educated now extended to the Emperor who actively lured thinkers to his court and discussed how to improve the morals and virtue of Rome’s leadership to fit their challenging times. He was also looking for a coherent ‘framework’ for Platonism as a ‘belief-system’ for him and his elite to back, and this was lacking due to so many divergent thinkers squabbling about what Plato’s later mystic utterances about ‘the One’ and the governance of the Universe meant. But such a synthesis of Plato’s ideas and expert analysis of his writings seemed to be offered by the leading Platonist writer Plotinus in the early-mid 260s, and he proceeded to think out and write a complex and intellectually rigorous new Platonist doctrine that matched Christian theology for its complexity and argued in favour of a beneficent ‘Supreme Being’, the creator and centre of the Universe, who wished his followers to do good and love each other like the New Testament Christian God.

Bust sometimes identified as being Plotinus, the Hellenistic philosopher from the 3rd Century Roman Empire.

Plotinus’ idea of a fellowship of devout and morally rigorous philosophers learning to do good works, love their fellow-men, and perfect their souls by mystic communion with the ‘One’ had some similarities with the 230s-250s Christian writings of Origen but did not involve denouncing the Olympian gods as ‘demons’ as the Christians did, so it appealed to the Emperor and his own close circle of courtly intellectuals. Gallienus duly invited him to seminars at his villas and ended up in 264 setting him up at an Imperially-funded estate in Campania to set up a school and teach annual classes of several dozen young Italian nobles and invited Greeks his beliefs. Had Gallienus lived longer, would he have started recruiting Plotinus’ ‘disciples’ to government? But ironically Plotinus himself believed that his followers and all proper Platonists had a pre-eminent duty to perfect themselves not the State, and he had a dim view of politicians and careerist administrators; he did not appear to have seen his school as an academy to train future administrators in ethics whatever Gallienus dreamed of.

There was substantially less physical damage to urban civilization in the Balkans and Asia Minor than in OTL – e.g. no sack of Athens or of the Temple of Diana at Ephesus. Asia Minor remained held by the rebel Macrianus II and his general Ballista until in 266 Gallienus could afford to send troops there to reconquer it once he had stabilised the lower Danube. The Goths, Roxelani and Borani had all been defeated and forced to supply tribute and military recruits to the Empire, and in 266 the Imperial generals Aureolus, Domitianus and Marcus Aurelius Claudius (later Emperor Claudius II), all tough ‘new men’ Illyrian officers in their late fifties, invaded Asia Minor and defeated and killed Macrianus in Phrygia. The latter’s army, weary of warfare and outnumbered, broke up and many deserted as soon as it became apparent that they were losing the first major battle, and Macrianus had to flee to save himself and ended up murdered by some of his officers as they hid in the hills. The officers then presented their leader’s head to Aureolus in the hope of pardon and a pay-off, but were soon executed ; the rebel region was soon overrun and Ballista, a Roman patriot first and facing a Persian counter-attack as he held onto Cilicia and the upper Euphrates region around Samosata, surrendered to save lives and was pardoned but pensioned off and required to live out of the way of further temptation in a guarded villa in Italy. This left the forces of the central Empire back on the upper Euphrates and in control of Cilicia for the first time since 260.

The German tribes did not penetrate as far as Italy as they did in OTL, due to Gallienus having better resources and full control of Marcomannia and Rhaetia. As a result of this, the lesser impact of the plague, the lack of ravaging of the southern Balkans and of Asia Minor, and the reconquest of the latter, the manpower and tax-revenues left to support the Empire by 270 were around 30% larger in c. 270 than in real life, putting less strain on the Empire. There was less damage to the Empire, although losses of manpower due to the 252 plague and civil wars meant that Gallienus was too short of men and money to attack the autonomist regime of Odenathus in Syria/ Palestine or the ‘Gallic Empire’ in 267-8. But in 267 a new force of tribal warriors from the western Ukrainian steppes, a mixture of the Heruls and a division of the Gothic people who had risen to prominence after the death of Kniva, threatened the Empire indirectly by moving with their oxen-drawn wagons into ‘Sarmatia’ (Wallachia) North of the lower Danube. They seizeed lands from the weakened tribes who had been defeated by Rome and forced to supply Gallienus with troops earlier, and their victims crossed the Danube into Lower Moesia that winter to demand that the Empire give them land and supplies as they were technically its subject allies and had lost their homeland.

Gallienus could not trust them and ordered a refusal so the angry Germans started to pillage and loot, and after a local Roman army - short of experienced men as these had been sent off to Cilicia and the Euphrates in the war of reconquest – was defeated and senior Imperial general Domitianus, hurrying back from his current command in Cappadocia, died in a riding-accident en route the Emperor had to intervene himself. He arrived in the southern Balkans in spring 268, having left Aureolus in charge at Mediolanum to face Postumus who was rumoured to have used his own German tribal aides to send messengers with gold to the steppes to encourage the embattled Goths and Heruls to attack Gallienus. Gallienus joined his commander in Dacia, Marcianus, and defeated the Heruls in a large-scale battle in SE Illyria (OTL Serbia) near Naissus as they arrived to pillage a so far unravaged region. The Germans asked for terms, and Gallienus granted those who wanted to leave safe passage from the Empire, enrolled some of their young warriors in his army, hired farmers to replenish plague-hit areas of Dalmatia and Noricum well away from the frontier, and gave consular ornaments as an ally of Rome to their chieftain Naulobatus. His just dealing duly impressed the other German tribal warriors currently ravaging Lower Moesia and into East Thrace, but his attempts to deal with them without a battle similarly were now prevented by the old Roman problem of ambitious generals.

Aureolus, his ego swollen by his successes in the Balkans and Asia Minor, had been angling for a promise of the throne as Gallienus’ heir, as the latter had no male relatives left to succeed him. He had been given no encouragement while not being sacked or placed under watch either, and now with his commander away he revolted at the Imperial military HQ at Mediolanum and declared his recognition of Postumus as his co-emperor – arguing to the soldiers that Gallienus had spoken of tackling Postumus next and they must avoid a ruinous civil war with the ‘Gallic Empire’ that would only benefit the over-ambitious Emperor not his loyal and over-worked soldiers. Gallienus hurried back to Italy before Postumus, probably caught by surprise and not in league with Aureolus , could cross the Alps, and defeated Aureolus at ‘Pons Aureoleus’ near Padua. He besieged the rebel in Mediolanum in June 268; Postumus, now in Lugdunum (Lyons), was unable to help Aureolus as his own general Laelianus seized Moguntiacum (Mainz)( in revolt and led the armies of upper Germany to set up a breakaway regime. Postumus recaptured the city and executed the rebel, but refused his troops’ request to sack the place. At Mediolanum, Aureolus held out in the walled city for weeks, and discontent grew among Gallienus’ senior officers at his refusal to negotiate; there were grumbles that Aureolus had had a point about getting the Emperor to name an heir and if Gallienus had opened talks and agreed to Aureolus being his successor the Empire could have taken advantage of the Gallic civil war and overthrown Postumus.

Praetorian Praefect Aurelius Heraclianus and two of Gallienus’ self-made Illyrian generals who had risen through the ranks, Marcus Aurelius Claudius (the new overall commander of the Imperial central army , the ‘Comitatus’) and Aurelian(us), led a plot to remove the Emperor. In early September, with the siege of Mediolanum still a stalemate, they were joined by other officers including the Dalmatian cavalry’s commander Cecropius and struck. Gallienus was informed at dinner in his camp by Cecropius that Aureolus had launched a sortie to attack his camp and he rode off to investigate with a small escourt without waiting for his bodyguards. The conspirators joined them to ‘help’, and Gallienus was attacked by surprise and cut down (aged probably in his late forties). (This is as in OTL, with a few modifications.)

Claudius (aged fifty-six) was made Emperor as the plotters’ choice in a meeting of the senior generals and was announced to the army; the soldiers were not fully satisfied until they received a large donative but had no alternative candidate to suggest. Messages were sent to Rome, where the Senate was relieved to be rid of Gallienus and tried to order the ‘damnatio memoriae’ (an official denunciation of the late ruler as a tyrant, smashing of his statues, and expunging of all inscriptions in his honour) but Claudius forced them to deify him as a god like past great emperors, eg Augustus , Vespasian, and Trajan) instead. Aurelian, the new ruler’s closest and most competent subordinate ,received Cecropius’ command of the Dalmatian cavalry as Claudius chose sacrifice that officer to the soldiers’ complaints about the murder being unpunished and had him executed; Praefect Heraclianus was either killed or committed suicide. Aureolus held out for a few weeks and declared himself Emperor, but was soon lured into holding talks with his old colleagues in the Imperial camp and once he was outside Mediolanum was seized and killed. Following Gallienus’ murder, his ‘Neoplatonist’ circle of attendant philosophers at court broke up; their most prominent member, the Egyptian philosopher and rigorous analyst and explicator of Plato, Plotinus, retired to a villa in Campania given to him by the Emperor to run his small private school for philosophers and died in 270. After his death the Imperial subsidy for the school was ended, as practical Illyrian military emperor Aurelian saw no need for the school and distrusted intellectuals; most of the teachers and graduates ended up moving to Greece, where there were plenty of wealthy intellectual nobles living around Athens to subsidise them, and helped to reinvigorate the ‘Academy’ (ie university) founded by Plato outside Athens in the 270s and 280s.

Coins depicting Zenobia of Palymeria. Shared under the CC BY-SA 2.5 licence.

In the East, meanwhile, late 267 had seen the surprise assassination of Odenathus at Games in his ‘capital’ of Palmyra by an officer with a private grudge, though as he was about to launch a campaign to reconquer the lost Roman fortresses and cities of the central Euphrates and Edessa rumour had it that ‘Great King’ Shapur was behind it. The Imperial loyalist regime in Egypt, commanded by Praefect of Alexandria Probus, might also have been glad to be rid of him and/or been told to get rid of Odenathus ahead of an attack by Gallienus on Syria planned for 269 –which the revolt of Aureolus aborted. The late ruler’s young son Waballathus technically succeeded him as ‘Princeps’, though neither Gallienus or later Claudius II recognised his government and Imperial officials in Palestine and Phoenicia were told to send their taxes to Rome instead – most dared not do this. In reality, power in Palmyra and Syria passed to Odenathus’ highly capable and politically active wife Zenobia, the half-Arab daughter of a deceased eastern Syrian desert tribal chief who had brought her father’s lucrative trading revenues to her husband’s treasury and who to respectable Romans’ horror rode dressed in armour with her husband, and later her son, at parades. Military leadership was taken by Zenobia’s general Septimius Zabdas, but she was in fact a more than capable strategist herself behind the scenes ; Roman propaganda now abused her as the ‘new Cleopatra’.

In late autumn 268 Claudius arrived in Rome to reassure the Senate and populace; with the Imperial army on the upper Danube weakened by having to send troops off to the Balkan campaign in 268 the Germans, particularly the Alemanni and Iuthungi, crossed the upper Danube that winter in search of food after a local famine and and overrun parts of Rhaetia. Worse, as Postumus had refused talks with Claudius’ new regime and declared war the Emperor had ordered his troops in Rhaetia to strike West into upper Germany that autumn to take advantage of army discontent at Postumus’ harsh repression of the Moguntiacum rebellion. The central Imperial government’s troops were reoccupying upper Germany with little resistance and in midwinter entered Moguntiacum as Postumus’ local army mutinied, and the Gallic emperor was unable to fight back as his repression led to another revolt in his troops garrisoning Helvetia (West Switzerland) and he had to suppress this. But while the central government was regaining control of the middle Rhine, the Germans looted at will across eastern Rhaetia They penetrated the Alps, and crossed the Brenner Pass in midwinter to enter Italy – the first such attack since the late 160s. At this point Britain and the lower Rhine recognised Claudius as Emperor too, but Gaul remained in rebellion. Having assumed the consulship in Rome on 1 January 269, Claudius left to confront the Germans in Northern Italy.

Postumus, bogged down in Helvetia, made an effort to reach the Rhine and retake his lost military heartland but early in 269 was killed by mutinous troops; they also killed or drove out some of his most capable senior officers and elected one of their number, a minor officer of obscure origins called Julius Marius, reputedly an ex-blacksmith, who ruled for two months before his deposition. Claudius advanced with his army to meet the plundering Germans, and defeated them at the battle of Lake Benacus (Lake Garda); he cleared Northern Italy of invaders and assumed the title of ‘Germanicus Maximus’. Shortly after this , Victorinus seized control of Postumus’ ‘Gallic Empire’, now reduced to Gaul and Belgica. (Events largely as in OTL, but with fewer usurpers and less of a German penetration than in reality; thus the Empire can recover quicker.)

Facing an untried new emperor and the reputed co-murderer of their patron Gallienus, the Heruli now incited some of the Goths in Sarmatia/Wallachia and their neighbours, the Gepids and Peucini to join them in another invasion of Moesia. Possibly over 100,000 men marched from the River Dniester to ravage the Euxine coast South along the Moesian and Thracian shores to the Bosphorus while most of the local army was absent in Cilicia in spring 269 confronting Zenobia, but failed to take walled Byzantium. They then headed West through Thrace, looting en route, to besiege Adrianople. Claudius heard of the attack while ‘mopping-up’ after the battle of Lake Garda; he sent Aurelian ahead with an advance-force (including the Dalmatian cavalry) to the Balkans, and allegedly turned down the temptation to take over the disorganised ‘Gallic Empire’ in the aftermath of Postumus’ murder from refuge officers of his who arrived in Italy with the comment that war with the national enemy must take precedence over his personal concern with pretenders.

He sent his younger brother Quintillus back to Rome, and led his main army to Thrace where Aurelian was harassing the Germans and forcing them back across the mountains into Moesia. Claudius joined up with Aurelian; they fought a bloody but inconclusive battle at Naissus (Nis) which forced the Germans to stop their march into Moesia, and then harassed them with ambushes to wear them down. The Germans started to run out of supplies as they straggled into the Haemus (Great Balkan) range, and Aurelian defeated them in an assault with the Roman cavalry at Doberus. The survivors reached safety in the mountains, but were blockaded there and starved out into the winter. Meanwhile a Palmyrene invasion of Egypt was successful; Praefect Probus was killed in battle at Babylon (a fortress near modern Cairo) and Zenobia secured control of Egypt, now in open defiance of the authorities in Rome as independent sovereign of a growing empire in the East. She cut off its corn-supplies to Rome to blackmail Claudius into recognising her regime, to no avail.


Timothy Venning is a respected Historian who won the London University History Prize in 1979 and whose latest straight history book is Cromwell's Failed State. He has also written multiple books of counter factual essays including Caesars of the Bosphorus, Eternal Caesars, King Charles or King Oliver and King Henry IX, all published by Sea Lion Press, and If Rome Hadn't Fallen.


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