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An Alternate History of the Roman Empire: A Combat of Champions

By Tim Venning

Follis of Licinius minted at Londinium. Image from the Classical Numismatic Group, Inc and shared under the CC BY-SA 2.5 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 eleven articles this took us to 305. We join the story at Dicoletian's abdication.

In spring 305 Diocletian became seriously ill and, despite a partial recovery, decided to abdicate, at the age of 61. He forced his co-emperor Maximian to do so too to preserve the administrative tidiness of both ‘Augusti’ retiring at the same time, though Maximian was initially unwilling. Constantius (now 58) was to take over the West and Licinius (now 44) the East. Diocletian arranged the nomination of two new junior ‘Caesars’ for them - Flavius Valerius Severus, a Danubian friend of Licininius in his forties, in the West with jurisdiction over Italy, Africa, and Pannonia, and Galerius’ sister’s son Maximin(us) Daia in the East. The latter was still in his thirties and seen as too young by many courtiers, but was a fervent religious traditionalist so pleasing to Diocletian and he may have been promised the post in return for accepting his uncle’s deposition and arrest . On 1 May 305 Diocletian abdicated at Nicomedia and Licinius moved there from his headquarters at Thessalonica; simultaneously at Mediolanum Maximian abdicated, retiring to his estates in southern Gaul, and Constantius took over. Diocletian retired to his grandiose new palace at Spalata (Split) in Dalmatia, near his birthplace. Severus, as ‘Flavius Valerius’, set up his base in Pannonia to watch the Danube frontier. Maximin, as ‘Caius Galerius Valerius’, took over jurisdiction of Syria and Palestine where he re-energised the Christian persecutions in 306 and ordered all citizens to sacrifice to the gods and obtain certificates or face arrest and penal labour. (In OTL this was enforced over all the Empire as Diocletian’s ‘Fourth Edict’ of persecution in 304, but soon halted in the West.) Arrested Christians were despatched to the Egyptian slave-mines by him, but Constantius halted all persecution of the Christians in the West; Maximin did not take his hints that the savagery of what was happening was counter-productive and kept up his own persecutions but, to his annoyance, Severus did not back him.

Licinius allowed Constantius’ son Constantine, now aged around 32, to leave his court at Nicomedia and travel West to join his father on the Rhine, acceding to Constantius’ second written request for it. Constantine left quickly before Licinius could change his mind and take him hostage, and travelled quickly and secretly West. He exercised particular caution across Severus’ dominions in case Severus tried to seize him as a hostage as a potential rival as Constantius’ heir, and arrived at Gesoriacum (Boulogne) to join Constantius en route to Britain. Constantius, as consul with Galerius in January 306, campaigned in Northern Britain that spring, assisted by Constantine, and pushed back a new ‘Pictish’ attack on Rome’s allies in Lothian and reached the Antonine Wall while his fleet landed troops in Fife to take the ‘rebels’ in the rear. But he had to abandon the campaign due to illness after reaching the Caledonian heartland North of the Tay. On 25 July, he died at Eburacum (York), aged 59; his troops elevated Constantine to be ‘Augustus’ - not even ‘Caesar’ which Diocletian and Licinius might have accepted to avoid a civil war - in defiance of the Diocletainic rules for succession whereby any appointments were done by the existing Emperors.

Severus was next in line to hold the senior rank, and either Constantine decided to challenge the existing system and reassert the hereditary principle and prodded the troops into the action or else his officers acted on his musings about it. For one thing, he knew from past contact with Maximian that the latter favoured the hereditary principle too and was planning to help his own son Maxentius onto a throne at some point - and once Constantine had acted this would probably push Maximian into acting too and so prevent Severus from stopping either of them . He secured the backing of the British troops and crossed from Britain to Gaul, where he secured the adhesion of his father’s armies on the Rhine; Spain also recognised him. The West, led by the army, was reverting to hereditary rule – as Maximian noted, leading to him refusing Diocletian’s written order to him to assist Severus.

(This is as in OTL, except for Licinius taking on Galerius’ role minus the persecutions; ditto with the following section, to 310, except for a few minor tweaks.)

Licinius appointed Severus, the existing ‘Caesar’, as ‘Augustus’ in the West in August 305, but recognised Constantine as his ‘Caesar’ in Britain, Gaul, and Spain; Severus took over at Mediolanum, ruling the rest of the West, but faced the resentment of Maximian who had been asking Diocletian to ensure the appointment of his own son Maxentius as the new ‘Caesar’. Constantine quickly had to face the Franks as they took advantage of Constantius’ death to raid across the Rhine; he defeated them and captured and executed their chieftains Ascaricus and Merogaisus. He then set up his Imperial headquarters at Trier, which was extended in size with a large new Imperial audience-hall (‘aula palatina’) and Baths.

Model of Augusta Treverorum (Trier) in the 4th century. Picture taken by Stefan Kühn and shared under the CC BY-SA 3.0 licence.

Notably the refugee Anatolian Christian teacher and propagandist Lactantius of Nicomedia, who had known Constantine while he was serving at the Eastern military headquarters in the 290s and knew him to be sympathetic to the Christians provided that they accepted the rule of the civil authorities and did not insult the Emperors, soon arrived to join Constantine’s court. He and other Christian refugees who followed started to encourage the new Emperor to think of it as his duty to humanity and the ‘One God’ (in whatever guise He was worshipped) to halt the persecutions and secure justice across the Empire, and as these devout and highly moral idealists argued that the Christian community only sought the freedom to worship as they wished and would ‘give unto Caesar the things that are Caesar’s ‘ – and they regarded rebellion as a sin – Constantine started to consider how valuable they could be to his cause. For the moment he remained a loyal worshipper of the Olympians and had his own private devotion to a superior ‘Supreme Being’ who ran the universe dedicated to the sun-god Sol Invictus, but he allowed Lactantius and the other refugees to get in touch with their co-religionists in the East to assure them of his goodwill and ask them to pray for him. This duly produced a trickle of interest in and support for him in the Christian communities. As Severus had halted the persecution in Africa in 305/6 to win support there the local Christians were emboldened to look for a more reliable pro-Christian emperor in Constantine as they made the most of the goodwill that their ordeal had won them.

On 28 October 306 Maxentius, backed by Maximian from Gaul, organised a mutiny of troops in Rome, where Severus was threatening to abolish the (now superfluous) Praetorian Guard; three tribunes, one of them the commander of the urban cohorts, led the latter in revolt and the Praetorians join in, supported by much of the populace. Maxentius, who only claimed the ‘Caesarship’ in his coinage at first so as not to provoke

Galerius, was recognised in Africa, did not attack the Christians, and defied Severus; Maximian joined him and recognised him as emperor on his own authority but then in

February 307 proclaimed himself ‘Augustus again, claiming that Diocletian had tricked him into abdicating. Severus (at Mediolanum) was now ordered by Licinius to depose Maxentius, and marched on Rome that spring; he reached the outskirts of Rome, but his troops mutinied and refused to fight against their old commander Maximian who was approaching with reinforcements from southern Gaul. Severus’ Praetorian Praefect Anullinus treacherously distributed money to the Severan troops to encourag disobedience, and Severus faced his army breaking up and had to retire to Mediolanum.

Maxentius now proclaimed himself ‘Augustus’, and was recognised as such by Constantine as a means of allying with him and Maximian – temporarily. Maximian pursued Severus into the Po valley, and the defeated Emperor sent envoys to him at Ravenna to negotiate as Galerius was sending him no help. Severus eventually agreed to abdicate provided that his life was spared, handed his official robes and circlet to Maxmian and hailed him as Emperor at a ceremony outside Ravenna, and was taken to Rome as a prisoner while Maxentius and Maximian took over Severus’ realm of Northern Italy, the upper Danube as far East as Pannonia, and Marcomannia.

(This is all Largely as in OTL.)

While Licinius campaigned on the lower Danube against the Sarmatians that summer, Maxentius and Maximian prepared the defences of Italy to meet an attack by Galerius, including heightening the walls of Rome. In September 307 Maximian visited Constantine at Trier, and arranged a family alliance; Constantine married his daughter Fausta, a few years his junior, and Maximian accepted him as ‘Augustus’. This left the West with three ‘Augusti’ and no ‘Caesars’, provided that Licinius was defeated by them, and predictably infuriated the retired and now powerless Diocletian who had to observe his entire political system for avoiding civil war collapsing under the weight of dynastic ambition . Licinius, refusing to accept the new arrangement, invaded Italy in September ; he reached Interamna but had difficulty with his soldiers who refused to aid Rome’s enemies by killing fellow-Romans and had to retreat. Maxentius reoccupied Northern Italy and moved on to take over Rhaetia too as far as the Noricum border. Diocletian emerged from retirement at Spalata to meet Maximian and Licinius that winter concerning the political crisis after Licinius had to accept that the West was lost and persuaded Diocletian to call on his old ally Maximian to mediate; they agreed to accept Maxentius as ‘Augustus’ at Maximian’s request, but only allowed Constantine to be ‘Caesar’ which he rejected and ignored.

Statue of Maxentius. Photo shared under the CC BY 3.0 licence.

In spring 308 , Maximian intrigued against his son, who had removed his bodyguard and was denying him the seniority and influence he wanted, while Constantine campaigned on the lower Rhine and constructed a bridge of boats over the river at Cologne. Maximian stirred up a mutiny against his son at Mediolanum in May, but failed to persuade the troops who he harangued at a parade to depose the latter and install him in the rule of Italy instead. He had to flee to Constantine in Gaul, but failed to have his Imperial title accepted elsewhere as Diocletian now insisted that his abdication of 305 was final. Constantine, Maximian, Licinius, and Maximin all met Diocletian at Carnuntum in October after Maximian swallowed his pride and approached Licinius and Maximin to appeal to Diocletian for him and a ‘summit’ was called, and they agreed on non-recognition of Maxentius who was proclaimed a public enemy.

Galerius’ nephew Maximin had his own designs to rule the Balkans area when he succeeded Licinius as ‘Augustus’ of the East, and they now fell out. Maximian, having failed to be recognised as full Emperor at Carnuntum as Diocletian refused to accept this , retired from his current home in Sicily to an estate in Gaul to (falsely) assure the suspicious Diocletain that he had no ambitions to seize Italy. Constantine and Maximinus refused Diocletian’s proposal that they accept the rank of ‘Sons of the Augusti’ rather than full Imperial rank so he had to give in and promise to recognise them as ‘Augusti’ once Maxentius was removed. Maximin was to rule the East with and then replace Licinius , and was sent to Antioch to govern the Eastern provinces. In 309 Licinius met and formed an alliance with Constantine against Maximin, and was betrothed to Constantine’s half-sister Constantia (one of Constantius and Theodora’s daughters). Maximin stepped up his persecution of Christians in the Eastern provinces, ordering that all citizens, even babies, participate in public sacrifices and that the blood of sacrificial victims be sprinkled on food in the markets so that all customers there had to eat ‘sacrificial’ food.

The idea was that the Christians would have to compromise their principles to eat, or would starve. He spread stories that arrested Christians had confessed to holding orgies at their famously secret ‘love-feasts’ and so were immoral and not really religious but depraved, which their enemies were all too keen to believe, and cleverly ‘tapped into’ the widespread feeling among the superstitious that the unexpected renewal of the civil wars in 305 must be a sign of disapproval of the current order by the gods so the State needed to appease them by punishing those who ridiculed the Olympians. He was boosted by petitions by local urban communities in towns in Syria, Phoenicia and Palestine that were hostile to their local Christians demanding that these ‘unpatriotic’ insulters of gods and emperors be expelled, which he took as a sign that most of the local citizenry wanted to be rid of the ‘undesirables’ but which in fact reflected more of a mixture of normal inter-communal feuding and a desire to seize the Christians’ property.

Maximin also started to formally subsidise the traditional religious cults with State funds, raised from the taxes, to enable them to take on lavish public welfare works of running schools, orphanages, and hospitals in order to win public support and undercut the reputation of Christian bishops and other philanthropists for doing good works and helping the poor. In 310 he instituted a system of regular State pay for all their priests in order to attract more volunteers to take the priesthoods up as a career. This might indeed have won substantial backing if it had been done long-term, but in the event was undercut by the shortness of his reign and also by the harshness with which he collected taxes and rounded up defaulters. He formed an intellectual alliance with and invited to his court the current leading Neoplatonist thinker Porphyry of Gaza in coastal Palestine, an admirer though not a direct pupil of the late Plotinus (d 270), and hired him to write more of his learned works synthesizing intellectually rigorous Platonist ethics and ‘saviour god’ cult mysticism around the figure of Plotinus’ ‘One’ supreme being. This was intended to continue Plotinus’ work by bringing in devotees of the fashionable, non-Christian Eastern saviour cults to take part in Platonist philosophy and win recruits to new Platonist schools for teenage boys of enquiring minds, but this plan was to be aborted by Maximin’s death in 313. Following that, the return of expelled Christian communities to their homes and the return of pro-toleration figures to the Imperial court in the East under Licinius saw Porphyry lose his official grants and retire into prudent seclusion in a remote area of Palestine , protected by sympathisers in the local administration, to complete his books in safety,

(As in OTL or based on probabilities.)

In 310 Constantine campaigned from the middle Rhine East to the Elbe; in his absence Maximian called an unauthorised meeting of the local nobles at Arles near his villa to lavish money on them in return for their accepting him as co-‘Augustus’ with Constantine , but he failed to secure much support. He was assumed to be planning to depose and kill his son-in-law, kill Crispus, and govern for his daughter Fausta and her next husband. He fled South as Constantine advanced, and was besieged in Massilia; when the town surrendered he was arrested and interned in a remote villa . Soon afterwards Maximian was found dead, aged around 65, possibly either suicide or murder on Constantine’s orders. Maximin now proclaimed himself ‘Augustus’ in the East in defiance of Licinius’ rights ; in retaliation Licinius finally came ‘off the fence’ in matters of religion and in 311 issued an edict abandoning the legislation against the Christians and allowing them freedom of worship provided that they prayed for the welfare of the Emperors and Empire; prisoners were released and churches reopened. (In OTL this was done by Galerius, who was seriously ill, and on his death shortly aftewards Licinius succeeded him as ‘Augustus’ of the East.) Maximin surprisingly had his Praetorian Praefect Sabinus send round orders to halt the persecution in his domains , as a gesture of goodwill to Licinius, and ordered the release of prisoners and no denunciations of private Christian assemblies provided that no public services were allowed – due to fear of a revolt by his lukewarm military commanders in favour of Licinius if he kept up his increasingly controversial policies? Maximin advanced to the Bosphorus that autumn to challenge Licinius for the rule of the Balkans, but his troops would not fight so he agreed to talk; after a ‘stand-off’ the two rulers agreed to a peace whereby Licinius ruled Europe and Maximinus ruled Asia. Maximin soon sent envoys to Rome to ally with Maxentius against Constantine and Licinius.

(Largely as in OTL; Maximian did have this surprise end after one double-cross too many. The events of 312-24 follow, largely as in OTL but with one major twist to extend Constantine’s gains of 312 to Egypt and add to his reputation and freedom of manoveure. Also events simplified to cut out some of the minor political/ military manoevurings . Behind the scenes, the more limited persecution of the Christians outside Maximin’s Levantine realm makes the anti-pagan ‘backlash’ by the Christians after they win Constantine’s support less supported or successful. )

The Chi-Rho symbol

Miltiades, the new Bishop of Rome, was now able to petition Maxentius for restoration of the episcopal churches after the latter issued a decree restoring all confiscated Church property. But that winter Maximin resumed the persecution in the East once his position against Licinius was more secure, six months after his orders for a halt to it. Diocletian died in November 311 at his palace at Spalata, aged around 68, with his plans for the Empire in ruins, regarded by the current elite as an irrelevance and even as to blame for the political mess. The showdown between Constantine and Maxentius now followed; Constantine, as consul for 312 with Maxentius denying him recognition and smashing his statues in Italy, declared war and advanced via Lugdunum and Vienne to the Southern Alps in March 312 to attack Italy. Constantine invaded Italy via NW Cisalpine Gaul , took Susa, and defeated Maxentius’ cavalry outside Turin. He marched East down the Po valley, winning a cavalry skirmish at Brescia, and Maxentius’ commander Praetorian Praefect Pompeianus left his main force in Verona while he retreated to fetch reinforcements from Rome. Constantine besieged Verona, and defeated and killed Pompeianus who arrived earlier than expected as he was besieging the town. In the late summer Maxentius retired to Rome as more troops from the upper Rhine arrived in N Italy via the Brenner Pass to reinforce Constantine, abandoning the Po valley. Constantine advanced South, and traditionally had a dream promising him victory if he adopted the Christian ‘chi-rho’ symbol – ‘In hoc signo vinces’ . He then put it on his men’s shields and used it on a standard. His personal account of this years later to Bishop Eusebius of Nicomedia did not make it clear that this incident occurred before the decisive battle against Maxentius, but this story was soon the ‘official version’.

Maxentius awaited Constantine at Rome, confident in the city holding out as it did against Galerius; he demolished the Mulvian Bridge across the river North of the city to prevent Constantine crossing, but later used a temporary wooden bridge across the site to lead his troops out to meet his rival in battle on the Western side of the Tiber. On 28 October 312 Constantine won the ‘Battle of the Mulvian Bridge’, at Saxa Rubra on the Northern outskirts of Rome, on the West bank of the Tiber; his cavalry broke up the enemy, whose infantry were pushed back into the river, and he personally led the final cavalry attack that broke the Praetorian Guard. Maxentius was drowned as his horse threw him off the temporary bridge into the Tiber in his army’s flight towards the capital, aged probably 34, and Rome fell to Constantine. Next day he entered Rome in triumph, with his troops parading the new ‘Chi-Rho’ standard. Constantine secured full control of Italy, Africa (which he sent Maxentius’ head to win popularity as the late ruler was loathed there for his aggressive tax-collecting among the local rich), and the upper Danube. The troops in Marcomannia and Dacia also accepted him as Emperor later in 312 as their commanders decided to refuse Licinius’ orders to send many of them East to help him fight Maximin (Not in OTL.) If that happened the over-stretched army in those provinces might be overwhelmed by a German attack from the North, so they backed Constantine instead and Licinius was powerless to stop them. Maxentius’ loyalists in his household, fearing that Constantine would murder his young son Romulus as a rival, got the boy away by ship from Ostia and gambled on help from the equally pagan and anti-Christian Maximin as their last hope – would he threaten to back the boy in a revolt in the West to keep Constantine at bay? Constantine was warned by his spies, and sent the small anti-piracy fleet from his Spanish lands , now landing his troops in Carthage, to chase them. The ‘Maxentians’ got away safely to pagan-ruled Egypt and landed at Alexandria, but Constantine was not going to let this potential threat to him develop so he remodelled Maxentius’ confiscated fleet at Misenum ready to pursue them . Hearing of Romulus’ arrival, Maximin ordered his fiercely pagan governor and officers in Alexandria to treat the boy well as a useful political weapon and to round up and kill any surviving ‘subversive’ Christians there who might try to hand him over to their probable ally Constantine (Not in OTL).

Constantine now abolished the Praetorian Guard as a potential source of trouble that was full of Maxentius’ fellow-ex-cadets in the senior ranks; he opened friendly relations with Bishop Miltiades of Rome, helped by his ally Lactantius who now hailed him as the divinely-protected rescuer of Christianity from the persecutors, and presented him with the Lateran Palace which had been previously assigned to Empress Fausta but now became the Bishop of Rome’s residence. He took over the building of the ‘Flavian Basilica’ in the Forum from Maxentius, and named it after himself, and reappointed Maxentius’ Praefect of Rome, Aradius Rufinus, as part of his policy of conciliation towards the nobility. But he wrote sternly to Maximin requiring him to abandon his persecutions or face war; Maximin grudgingly agreed to allow freedom of worship in his domains and the return of Church property and forbid forced conversions, using the argument that some priests had claimed that a prophecy promised him victory against Licinius if he did so. All Christian prisoners and slave-labourers were released, and it was Constantine that received the praise for achieving this with even the more militant traditional priesthoods in Syria and Egypt having to accept that the new religion had proved harder to crack than anticipated and that the seething resentment of large urban communities at the harsh and often biased judicial persecutions had ruined Maximin’s reputation.


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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