An Alternate History of the Roman Empire: New System, New Challenges

By Tim Venning


Roman banner shared under the CC BY 3.0 licence

This long 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 eight articles this took us to 284 and the following rulers.


Marcus Aurelius 161-190

Pertinax 190-197 (and co-ruler, titular, Titus Aurelius 190-2)


Septimius Severus 197-218


(Caracalla, co-ruler 198-217)


Geta Severus, 218-228


Alexander Severus, 228-242


Gordianus I, 242-243.


Gordianus II, 243-251.


Gordianus III, 243-252.


Trebonius Gallus, 252-253.

Aemilius Aemilianus, 253.


Lucius Valerian(us), 253 -260.


Gallienus, 253-268.


Claudius II, 268-270.


(Gallic breakaway Empire: Postumus 264- 269, Victorinus 269-70, Tetricus 270-274.)


Aurelianus Restitutor Orbis’, 270 - 280.


Probus, 280-284.


Diocletian, 284-305.


Diocletian quickly decided to co-opt a colleague as the Empire was too large for one man, and was also uneasy at his own lack of battlefield experience. He needed a general who could defeat usurpers easily – and one he could trust, which meant another Illyrian ‘self-made’ man. He also formulated an ambitious overhaul of the entire administrative system – going beyond Aurelian’s piecemeal expansion of it to create a formal new system, not just tinkering with it and expanding numbers as his old employer had done. He ensured a hierarchical pyramid of officials responsible to their superiors and ultimately to him, and this duly fed into a new social ‘gap’ that grew up in contemporary terminology to separate the ‘upper classes’ (that is, reckoning either by birth or by nature of employment and pay), the ‘honestiores’, and the ‘lower classes’, the ‘humiliores’, around 290-320. The acquisition of well-paid jobs, particularly in the expanded bureaucracy or military, and thus of social status was now far more dependant on Imperial patronage and entire ‘bureaucratic dynasties’ grew up at court, giving extra power as a dispenser of jobs and wealth to the Emperor – as presumably planned by the shrewd and watchful Diocletian.

The precise dating of this is obscure as is the question of whether Diocletain had a ‘master-plan’ which he followed or gradually built up a new system of government through a series of ‘ad hoc’ measures, but in the next two decades he also noticeably increased the Eastern-style pomp and majesty of the Imperial office. With an emphasis on ‘top-down’ orders being obeyed.and on the Emperor as hero, he became a remote figure treated with exaggerated deference as ‘Dominus et Deus’ (‘Lord and God’) rather than an approachable ‘first citizen’. He vastly increased the size and scope of both the bureaucracy and the Court offices to become an autocrat like the Persian ‘Great King’ – unthinkable to the equally irascible but modest Aurelian. It is possible that his idea was to compensate for not being a successful and popular general like his predecessors by establishing his authority another way; and as he had no son, only one daughter, he probably had a preference for achievement by talent and patronage rather than birth due to family circumstances. Like Gallienus and the first three lower-class ‘Illyrian Emperors’ (Claudius II, Aurelian and Probus), he had no interest in flattering and soothing the sensibilities of the disgruntled Roman nobility in and around the capital, though unlike Aurelian he did not mind employing them in the higher ranks of the bureaucracy . He also had a sentimental attachment to the old religious cults of Rome and duly observed the traditional round of religious ceremonies in honour of the ‘Olympian’ gods wherever he was residing at the time, bringing in priests from Rome to conduct the ceremonies. He also presided at the Olympic Games in 288, 292 and 296 in Greece and rebuilt the neglected and crumbling precincts at Olympia, but this was more of a piece of political ‘spin’ to win over the strongly traditionalist elites of the Greek (and Greco-Italian, Greco-Anatolian and Greco-Syrian) cities who supplied the athletes and play up his role as the heir of their favourite ruler Hadrian.

In June 286 he raised his trusted fellow-officer, the low-born Danubian Maximian (aged around forty and a few years his junior) to be ‘Caesar’ and deputy ruler: his intention was that Maximian should concentrate on the West while he resided chiefly in the East. Maximian took the names of ‘Marcus Aurelius Valerius’ to complement Diocletian’s new names of ‘Caius Aurelius Valerius’. He became ‘Herculius’, named after the renowned Ancient Greek hero and god Heracles (‘Hercules’ to Romans) to Diocletian’s superior ‘Jovius’ (ie ‘Jove’ that is ‘Jupiter’), ie the supreme god - showing which gods they regarded as their exemplars and their celestial equivalents. They came to call their personal guards-regiments the ‘Joviani’ and ‘Herculiani’, and like Aurelian filled them with loyal ‘self-made’ provincials who could later be given major posts as provincial ‘duces’ (military commanders) . Diocletian also became ‘Germanicus Maximus’, at the conclusion of his inaugural Danube campaign in spring 287 to make sure that the tribes beyond the lower Danube recognised that he was to be treated with as much respect as Aurelian and Probus. On 1 April 287 Diocletian made Maximian his co-‘Augustus’ and sent him to the Rhine for a similar demonstration of military might, after which Maximian set up his court and military headquarters at Mediolanum. Diocletain, who rarely visited the West and tended to spend his summers in Greece or his home region of Dalmatia, based himself at a new Imperial court and palace at Nicomedia in Bithynia, within reach of either the lower Danube or the East should a new war break out in either region. The provincial administration across the Empire was soon completely overhauled to increase the number of provinces, sub-dividing all but the smallest provinces into several new ones, so that there were fewer troops and other resources in the hands of each governor and they were less able to revolt.

A new class of regional ‘super-provinces’ was created between the ordinary provinces and the Emperor, the ‘vicarates’ whose holders, the ‘Vicars’, each controlled a substantial area of the Empire – Britain; (Northern) Gaul with the Rhine; the ‘Five/Seven Provinces’ (Southern Gaul); Spain; ‘Italia Annoniaria’ (Northern Italy and Rhaetia); ‘Italia Suburicana’ (Rome and Southern Italy with Corsica, Sardinia, and Sicily); Pannonia (with Noricum); Africa; Moesia (with Epirus, Macedonia, and Greece); Thrace (with the Lower Danube area); ‘Asiana’ (‘Asia’, with Lycia and Pamphylia); Pontus (with Bithynia and Cappadocia); and ‘Oriens’ (Cilicia, Syria, Mesopotamia, Palestine, and Egypt). The vicar of ‘Oriens’ was styled ‘Count’ and the governor of Egypt became ‘Augustal Praefect’. From now on, each ‘Augustus’ had his own Praetorian Praefect, whose duties were already largely administrative but became more so under Diocletian, and a separate administrative apparatus whose ranks were rigidly hierarchical and which was centred on the functions of the Imperial Court.

Diocletian raised the size of the Imperial armies, one ‘Comitatus’ for each ‘Augustus’, substantially and endeavoured to secure regular recruitment by an annual conscription; he made military service hereditary. The number of fortresses and other defences on the frontiers was also increased, and local military commanders ‘(‘duces’) were appointed for the frontier provinces with authority independent of the governors (‘correctors’).The ‘duces’ were often from the Emperor’s own trusted circle of officers in the ‘Comitatus’, ie central army attendant on him – and the most crucial jobs went to ex-rankers (Aurelian had done this also). Around 290 Diocletian introduced two new senior offices to head the imperial ‘Comitatus’ - supreme infantry and cavalry commanders, the ‘Magistri Militum Praesentales’, one for the infantry (‘Peditum’) and one for the cavalry (‘Equitum’). He also raised a new force of bodyguards for each ‘Augustus’, independent of the Praetorians - the ‘Scholae’ regiments – and enrolled a mixture of young aristocrats and sons of court officials in these. This was all carried out as occurred in OTL, but in this version the Empire had suffered less from Germanic ravaging and there was a more prosperous urban and rural economy and more men to pay taxes and join the army.


Thus the fabric of Roman civilization was less badly affected by the burdens of Diocletian’s massively expensive bureaucratic state or his creation of a stronger army of around 250,000 men rather than the pre-250 strength of around 170,000 , and the resulting decline of the ‘civic spirit’ was less than in OTL. The urban classes, on whom the burden of taxes and civic duties fell, were better able to pay the price of the extra demands on them – and fewer towns were physically damaged due to fewer raids than in OTL. Less ravaging of the countryside meant less of a flight of peasantry from the farms and more food being grown to feed the armies and cities, and more men available from the 270s onwards to join the enlarged armies. The plague of the 250s had however reduced manpower so more Germans have to be brought into the Empire and settled on the land. The lack of ‘barbarian’ ravaging in Gaul, Greece, and Asia Minor and the lesser impact on the Balkans from 250 to 278 meant that the Empire could raise more tax-revenues, soldiers, and food from these areas in particular. The restored civilization of the C4th shown here was still a society of ‘uncertainty’ compared to the confidence of the C2nd, in danger from Germanic attack, but it had more resources than the real-life Later Empire did.

Maximian’s new commander of the ‘Classis Britanniae’ (an English Channel naval force formed to deal with pirates), the self-made naval captain Marcus Carausius, probably a humbly-born ex-pilot from Menapia (Belgian coast) or possibly Irish, created the first crisis for the new version of the Empire. Ironically, the obsessive Diocletian had been expecting any revolts to come from the senior generals who he had sidelined for the throne in 284 and in 285-8 pushed many of them into early retirement on various excuses; a rebel admiral was unexpected . In autumn 287 the brilliant but greedy and ambitious Carausius, a ‘bluff’ and popular officer in his late forties, discovered that there had been complaints against him for intercepting too many Frankish pirates (from OTL Holland) only on their way home from not on their way to raids and then keeping most of their loot for himself. Before he could be arrested he raised the fleet at Gesoriacum (Boulogne) in revolt with stories that the Illyrian ‘Imperial yes-man’ sent to command the local province as ‘dux’ (military commander) was planning to get him and the senior officers all replaced by his own men, and crossed from Gesoriacum to Britain where he murdered those provincial governors and military commanders who would not join him when summoned to a crisis meeting at Rutupiae and secured the troops with a donative of seized tax-money. He proclaimed himself as Emperor, and controlled Britain and Northern Gaul (centred on Gesoriacum). Maximian was busy dealing on the lower Rhine with the still obstreperous Franks by appointing their new king, Gennobaudes, as a Roman vassal-ruler to rule the lands at the mouth of the Rhine – a measure that solved the local invasion-threat for a decade or so. He could not spare the time to deal with Carausius and had no ships so he could not attack Britain – and a defeat blockading walled Gesoriacum could spark off a new revolt by Lower Rhine commanders who resented him as a non-local nominee of Diocletian whose main priority was clearly the Danube and Carpathian frontiers.

Coins Carausius had minted during his OTL rule as Emperor of Britain as shared under the CC BY-SA 3.0 licence

Maximian tried instead to negotiate to flatter and pay Carausius to abdicate, but this failed and as Diocletian ordered him to deal with the rebel he built a rival fleet and called in more naval forces from the small Roman fleet in the Mediterranean, an anti-piracy force which was not used to Channel tides and whose oared galleys were useless. Eventually , once he had sailed ships built and crews trained he attacked Gesoriacum by land and sea in spring 289, but his ships were defeated by Carausius thanks to the latter’s superior seamanship and the rebel was able to reinforce and supply the port from Britain. Maximian had to abandon the siege and after a tense exchange of letters with Diocletian was allowed to negotiate to prevent another humiliation causing local revolts. He concluded a treaty a few months later accepting Carausius as a fully legal Emperor with him and Diocletian agreed to this, but it was only a ‘stopgap’.

Diocletian went to Egypt following raids on the upper Nile valley by the desert tribes of the Blemmydes in 291, and campaigned against them and enlarged and re-trained the long neglected Egyptian garrisons – and also found himself impressed by the mass-loyalty that the ancient Egyptian cults maintained among the public after up to 3000 years. The advantages that the wealth, land-owning temples had secured by providing jobs as junior priests and tenant-farmers for the rural young men and the way that public life and festivals centred on the cultic year had clearly stimulated devotion and loyalty, and Diocletain considered that the Roman cults in Italy – also run by the hereditary aristocrats but less connected to the people – could benefit for this example. If the temples in the Empire provided free food and lots of public festivals like the Egyptian ones did fewer people would defect to the cults of ‘alien’ saviour gods or the egalitarian cult of the Christians, whose refusal to sacrifice to the Emperor was already irritating him as unpatriotic.


Among those of his younger officers in the ‘comitatus’ who was inspired by his lectures to his proteges on the success of the traditional religion in Egypt and how Rome could learn from this was the future emperor (and ‘pagan’ enthusiast) Maximinus Daia, in his twenties ; and among the Emperor’s successful commanders on this expedition was another aggressively traditionalist foe of the Christians and all ‘alien’ new cults , Galerius, in his mide-thirties. Diocletain advanced up the Nile as far as the cataract at Philae to agree a peace-treaty with Nubia, the formerly allied trading-kingdom to the South, and was agreed that the representatives of Rome and Nubia would meet annually there to renew the treaty; he settled Nubian mercenaries on the frontier to provide extra defences against raiders. He then returned to the Danube for another ‘Sarmatian’ campaign over the river into Wallachia in 292, securing a treaty of vassalage, levies of troops, and loot as ‘Sarmatius Maximus’ to fend off the danger of raids. The Triumph for this held at Nicomedia in that winter heralded the formal establishment of his court and ‘capital’ there, though in practice he usually spent part of each year either at Sirmium on the middle Danube to watch the Dacian frontier or at Antioch to watch Persia .

Discuss this Article

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.

© 2019, Sea Lion Press.

  • facebook-square
  • Twitter Square