Publius Licinius Egnatius Gallienus Augustus was now sole ruler of the vast Roman Empire, or rather: the sole legitimate ruler. Most western provinces were in the hands of Postumus, ruler of the ‘Gallic Empire’, while Gallienus soon had to deal with usurpers and rebels in the eastern provinces as well. He would spend much of the remaining eight years of his reign on campaign, fighting enemies from within and outside the Empire. But Gallienus certainly did not persecute Christians. Perhaps because he had too many problems on his mind, or perhaps because he was genuinely tolerant and did not see the Christians as enemies, the emperor quickly abolished the two Edicts issued by his father Valerianus. Church possessions that had been confiscated were returned and Christians were also granted access to their cemeteries again. They were basically allowed to practice their religion freely and it has been hypothesised that Christianity became a religio licita – an allowed religion – under Gallienus.
After Valerianus’ defeat and capture at Edessa in 260, the Persian army roamed freely through the Roman provinces of Syria, Cilicia and Cappadocia. In his Res Gestae Divi Saporis, Shapur claims to have captured 36 cities and towns. Once again the Persians sacked Antiochia, which can only have barely recovered from the previous sack in 253. It seems likely that the Persians divided their forces and sent smaller columns to all corners of the Roman provinces to do as much damage as possible. Perhaps a second Persian army invaded Cappadocia through Armenia and dealt with cities on the other side of the Taurus Mountains, such as Sebaste (Sivas), Caesarea (Kayseri) and Iconium (Konya). It should be noted that the Persians never intended to annex the territories they ravaged. Like the Romans, the Persians had many borders to defend and they simply lacked the means and the manpower to enlarge their already overextended empire. They did take many prisoners during their raid and deported these people to Persis, Parthia, Elam and Assyria.
As some of the Persian columns retreated east with their loot, they came under attack from the surviving Roman forces in the region. The Roman successes were just little pinpricks, but enough for the soldiers to proclaim their commander Macrianus emperor. According to the notoriously unreliable Historia Augusta, this Macrianus was the captured emperor’s most important general. The authors of the Historia were likely exaggerating, and he may have been no more than a quartermaster, but Macrianus did get support from Ballista, presumably one of the praetorian prefects (Shapur claimed to have captured the other one). Macrianus had his sons Macrianus junior and Quietus made co-emperors, and one of the reasons may have been that he was already quite old and lame to boot. The two Macriani assembled an army, crossed over to Europe and in 261 met an army sent by Gallienus somewhere in Illyricum or Thrace. The latter army was led by two of Gallienus’ generals, Aureolus and Domitianus. No details of the ensuing battle have been recorded, but the force of the usurpers was destroyed and father and son were killed.
In the meantime, the struggle against the remaining Persian forces had been led by one Septimius Odaenathus. Both a Roman citizen and a native of Palmyra, he was the self-proclaimed ras (‘lord’) of this famous desert city. We do not know whether he held any formal political or military office, but it is clear that he rallied the Roman forces in the region and combined them with troops from Palmyra, a city whose archers, camel riders and cataphracts had an excellent reputation. After clearing the Roman provinces of invaders, Odaenathus went on the offensive. In 262 he recaptured Nisibis and invaded Sassanid territory. He then chased the Persians all the way back to Ctesiphon on the Tigris, before returning to Syria where he had Quietus and Ballista murdered. In spite of these successes, Odaenathus never seems to have pondered to declare himself emperor. He was loyal to the bone to Gallienus and never minted any coins with his own image.
Gallienus was lucky to have such an ally, for his throne was never secure. In Egypt, the prefect Mussius Aemilianus revolted, but his rebellion was short-lived. It was crushed, in 261 or 262, by Theodotus, a general loyal to Gallienus who became the new prefect of this most vital province. Aemilianus was captured, sent to Rome and strangled in prison. All of these successes allowed Gallienus to celebrate his decennalia, his first decade as emperor, in 262. The Historia Augusta has left us a vivid description of the celebration which, for once, has a ring of truth to it:
“First of all, he repaired to the Capitol with the senators and the equestrian order dressed in their togas and with the soldiers dressed all in white, and with all the populace going ahead, while the slaves of almost all and the women preceded them, bearing waxen flambeaux and torches. There preceded them, too, on each side one hundred white oxen, having their horns bound with golden cords and resplendent in many-coloured silken covers; also two hundred lambs of glistening white went ahead on each side, besides ten elephants, which were then in Rome, and twelve hundred gladiators decked with all pomp, and matrons in golden cloaks, and two hundred tamed beasts of divers kinds, tricked out with the greatest splendour, and waggons bearing pantomimists and actors of every sort, and boxers who fought, not in genuine combat, but with the softer straps. All the buffoons also acted a Cyclops-performance, giving exhibitions that were marvellous and astonishing. So all the streets resounded with merry-making and shouts and applause, and in the midst the Emperor himself, wearing the triumphal toga and the tunic embroidered with palms, and accompanied, as I have said, by the senators and with all the priests dressed in bordered togas, proceeded to the Capitol. On each side of him were borne five hundred gilded spears and one hundred banners, besides those which belonged to the corporations, and the flags of auxiliaries and the statues from the sanctuaries and the standards of all the legions. There marched, furthermore, men dressed to represent foreign nations, as Goths and Sarmatians, Franks and Persians, and no fewer than two hundred paraded in a single group.”
Later, in 264, Gallienus also held a triumph to celebrate Odaenathus’ successful campaign against the Persians. The Historia Augusta claims he also had his father Valerianus deified, but there is every reason to doubt this claim. It is not mentioned in any other source, and Valerianus was likely still alive by 264.
Gallienus’ chief opponent closest to Rome was Marcus Cassianus Latinius Postumus, a Batavian who ruled the so-called ‘Gallic Empire’, but was a Roman through and through. Even though Postumus never attempted to march on Rome to depose his rival, Gallienus had stationed an army close to Mediolanum (Milan) to keep a wary eye on his opponent. It was an army which, as is demonstrated by coins, was composed of vexillationes from at least thirteen different legions. There was a particularly strong cavalry detachment at Mediolanum as well. Sometimes this Milanese army is seen as part of Gallienus’ reform of the Roman army, as a mobile reserve behind the stationary borders further to the north and with a stronger emphasis on cavalry. All of this has been challenged, and it seems more likely that the main purpose of this army was to guard the frontier with the Gallic Empire, which was just a little further to the west.
In the 260s, Gallienus attacked Postumus at least once (perhaps in 265) and probably more often, but despite some victories, he never achieved any lasting success. The Historia Augusta even claims he was wounded by an arrow during a siege. Postumus was a competent general, who did not just protect his provinces against attacks from Gallienus, but also from the Germanic tribes living to the north of the Empire. He is credited with creating a second line of defences behind the traditional limes. This second line ran along the road from Bononia or Gesoriacum (Boulogne-sur-Mer) on the Channel to Bagacum (Bavay), Atuatuca (Tongeren) and finally Colonia Claudia Ara Agrippinensium (Cologne) in present-day Germany. Modern historians refer to this road as the Via Belgica, but we do not know what it was called in Antiquity. Many of the castella along the Rhine, such as Matilo and Praetorium Agrippinae, seem to have been abandoned around this time. Nevertheless, the Rhine remained the border of the Roman Empire until shortly after 400.
In the East, Odaenathus launched a second offensive against the Persians. In 266, his army again reached Ctesiphon and again Gallienus took credit for the Palmyrene success. The emperor was not ungrateful though. He rewarded his ally by granting him the titles of dux and corrector totius orientis. The latter title was likely more or less the same as the one granted to Gaius Julius Priscus, the emperor Philippus Arabs’ brother (see Philippus Arabs: The Years 244-249). It basically made Odaenathus governor of all the eastern provinces, his authority superseding that of all the individual governors. Even though he had not himself fought the Persians, Gallienus began styling himself ‘Persicus Maximus’ in inscriptions and papyri. Coins minted in Antiochia demonstrate that he also considered himself the RESTITVT[OR] ORIENTIS, the restorer of the Roman East. Odaenathus was hardly more modest: he named himself the King of Kings, a conscious attempt to mimic the defeated Shapur.
In 267, King Odaenathus and his son Herodes were murdered, probably at Emesa (modern Homs in Syria). The motives behind the murder will likely never become clear. There may have been a family feud, as the assassin was reported to be the king’s cousin. According to another theory, Gallienus had orchestrated the murder because he feared that Odaenathus was becoming too powerful. The king was succeeded by his young son Vaballathus, but actual power lay with the boy’s mother, Odaenathus’ second wife Zenobia, who acted as the boy’s regent. She is sometimes accused of involvement in her husband’s assassination, and the fact that her son profited from the murder of his stepbrother and heir to throne may be seen as circumstantial evidence. Young Vaballathus inherited his father’s titles of King of Kings and corrector totius orientis, even though Gallienus had never consented to this.
There were plenty of disasters during Gallienus’ eight-year reign as sole emperor. One of them was an earthquake in Asia, probably in 262, which caused massive damage. Gallienus proceeded to consult the Sibylline Books and make many conciliatory sacrifices to Jupiter. The earthquake damaged the city of Ephesus, which also became the victim of a new Gothic invasion in about 267. On that occasion, the Goths damaged the famous temple of Artemis, one of the seven wonders of the Ancient World.
The attack on Ephesus was part of a series of large-scale raids by the Goths, who were now joined by the Heruli, another Germanic tribe. They seem to have built or commandeered another fleet and sailed through the Bosporus, attacking Byzantium and Cyzicus. Although they may have suffered a defeat against a Roman fleet led by a certain Venerianus (who was killed), this did not stop them from continuing their raids. The islands between modern Greece and Turkey were an easy prey. While some groups of Goths and Heruli swung into Asia and attacked Ephesus, others raided the provinces of Macedonia, Epirus and Achaea. Several cities were captured and pillaged, the most famous among them Athens, which was taken by a band of Heruli. This was more than a little ironic, as the Athenians had repaired their walls just a few years previously. While retreating from Athens, the Heruli were suddenly attacked by some Athenian militia under the command of Publius Herennius Dexippus. The Athenians inflicted some casualties, raising Roman morale, but the invading army remained more or less intact. Dexippus would go on to write a history about the Gothic Wars, of which unfortunately only fragments survive.
The Germanic invasions had drawn the emperor Gallienus and his competent general Marcianus to the region (the latter is not to be confused with the usurper Macrianus). When the Heruli tried to cross the Rhodope Mountains, they were defeated near the river Nestos, probably in 268. Their defeat cannot have been total though. A late source, the ninth century chronicler Syncellus, claims that the Herulic leader Naulobatus made a deal with the Romans. He was given senatorial rank and in return probably had some of his men join the Roman army. Although Syncellus wrote centuries after the facts, he may still have had access to Dexippus’ work, and the story may very well be true.
Then news reached the emperor about another rebellion. This time it was Aureolus who had renounced his loyalty to his emperor. Several years ago, he had been involved in the defeat of the usurpers Macrianus senior and junior (see above), and now he was commander of the emperor’s cavalry at Mediolanum. The fact that Gallienus was far away and that he had many good men under his command likely contributed to the rebellion. Leaving Marcianus behind to do the mopping-up, Gallienus raced back to Italy and confronted the usurper between Mediolanum and Bergomum (modern Bergamo). Aureolus was thoroughly defeated at a bridge which was later named after him: Pons Aureolus, or Pontirolo. He did manage to escape with his life and fled back to Mediolanum, where Gallienus put him under siege. During that siege the emperor was killed by his own men. The assassination was not a spontaneous action, but the result of a well-organised conspiracy. When the fake news was reported to him that Aureolus had launched an attack, Gallienus rushed out of his tent without his bodyguards and was subsequently stabbed to death.
Several important officers seem to have been involved in the plot. All of them had an Illyrian background (Illyricum was a generic term for the Balkan provinces). The praetorian prefect Heraclianus was certainly involved, and so was a Dalmatian cavalry officer named Cecropius, who dealt the emperor the final blow. Two future emperors may have participated in the plot as well. Marcus Aurelius Claudius (the future emperor Claudius Gothicus) was one of them, Lucius Domitius Aurelianus (the future emperor Aurelianus) the other. The Historia Augusta also mentions general Marcianus among the chief conspirators, but since he was still in the Balkan region this seems a bit unlikely. Gallienus’ third son Marinianus was later killed as well, as was his brother Valerianus Minor. This was a clear attempt to eradicate the entire imperial family. According to the anonymous Epitome De Caesaribus, Gallienus was interred in a tomb along the Via Appia, near the ninth milestone. A building identified as the Mausoleum of Gallienus still exists.
- Aurelius Victor, De Caesaribus 33 (translated and annotated by H.W. Bird);
- Epitome de Caesaribus 33;
- Historia Augusta, The Two Gallieni;
- Historia Augusta, The Lives of the Thirty Pretenders (Odaenathus);
- Res Gestae Divi Saporis;
- Zosimus, Historia Nova, Book 1.36-41.
- Adrian Goldsworthy, The Fall of the West, p. 114-118 and p. 123-125;
- Henk Singor, Constantijn, p. 106-107;
- Timothy Venning, A Chronology of the Roman Empire, p. 604-609.
 Henk Singor, Constantijn, p. 106-107.
 Most, if not all, of the years given in this post are conjectural. The chronology of events during the Crisis of the Third Century is often hazy.
 The Two Gallieni 8.
 See Adrian Goldsworthy, The Fall of the West, p. 117-118.
Updated 10 April 2023.