Ancient Roman and Greek Coins:

Gallienus
218 – 268

Gallienus, AE antoninianus, Rome mint. Sole reign.
Obverse: GALLIENVS AVG, radiate head right.
Reverse: SOLI CONS AVG, Pegasus springing right.
Officina letter A offset to right of exergue.
RIC V-1, Rome 283 var (mintmark A); Goebl 712

Gallienus, Antoninianus, 260-268, Antioch
Obverse: GALLIENVS AVG. Radiate, draped, cuirassed bust right, seen from behind
Reverse: AETERNITAS AVG, She-wolf standing right, suckling twins
Palm branch right in exergue
RIC V, Part I, 628; Göbl 1628c

Gallienus, Bi. antoninianus,  Rome mint.
Obverse: GALLIENVS AVG, radiate, cuirassed bust right.
Reverse: LAETITIA AVG, Laetitia standing left, holding wreath and anchor.
Something in exergue, but unknown to me at this point.
Rome 226

Gallienus, Antoninianus, 260-268, Sole Reign, Asia, Antioch
Obverse: GALLIENVS AVG Radiate, draped, cuirassed
bust right, seen from behind
Reverse: AETERNITAS AVG She-wolf standing right,
suckling twins (No Palm branch right in exergue)
RIC V, Part I, 628; Göbl 1628c

Life

Rise to power:
          The exact birth date of Gallienus is unknown.  The Greek chronicler John Malalas and the Epitome de Caesaribus report that he was about 50 years old at the time of his death, meaning he was born around 218.  He was the son of emperor Valerian and Mariniana, who may have been of senatorial rank, possibly the daughter of Egnatius Victor Marinianus, and his brother was Valerianus Minor.  Inscriptions on coins connect him with Falerii in Etruria, which may have been his birthplace; it has yielded many inscriptions relating to his mother's family, the Egnatii.  Gallienus married Cornelia Salonina about ten years before his accession to the throne.  She was the mother of three princes: Valerian II, who died in 258; Saloninus, who was named co-emperor but was murdered in 260 by the army of general Postumus; and Marinianus, who was killed in 268, shortly after his father was assassinated.
          When Valerian was proclaimed Emperor on 22 October 253, he asked the Senate to ratify the elevation of Gallienus to Caesar and Augustus.  He was also designated Consul Ordinarius for 254.  As Marcus Aurelius and his adopted brother Lucius Verus had done a century earlier, Gallienus and his father divided the Empire.  Valerian left for the East to stem the Persian threat, and Gallienus remained in Italy to repel the Germanic tribes on the Rhine and Danube.  Division of the empire had become necessary due to its sheer size and the numerous threats it faced, and it facilitated negotiations with enemies who demanded to communicate directly with the emperor.

Early reign and the revolt of Ingenuus:
          Gallienus spent most of his time in the provinces of the Rhine area (Germania Inferior, Germania Superior, Raetia, and Noricum), though he almost certainly visited the Danube area and Illyricum in the years from 253 to 258.  According to Eutropius and Aurelius Victor, he was particularly energetic and successful in preventing invaders from attacking the German provinces and Gaul, despite the weakness caused by Valerian's march on Italy against Aemilianus in 253.  According to numismatic evidence, he seems to have won many victories there, and a victory in Roman Dacia might also be dated to that period. Even the hostile Latin tradition attributes success to him at this time.
          In 255 or 257, Gallienus was made Consul again, suggesting that he briefly visited Rome on those occasions, although no record survives.  During his Danube sojourn (Drinkwater suggests in 255 or 256), he proclaimed his elder son Valerian II Caesar and thus official heir to himself and Valerian I; the boy probably joined Gallienus on campaign at that time, and when Gallienus moved west to the Rhine provinces in 257, he remained behind on the Danube as the personification of Imperial authority.
          Sometime between 258 and 260 (the exact date is unclear), while Valerian was distracted with the ongoing invasion of Shapur in the East, and Gallienus was preoccupied with his problems in the West, Ingenuus, governor of at least one of the Pannonian provinces, took advantage and declared himself emperor.  Valerian II had apparently died on the Danube, most likely in 258.[11] Ingenuus may have been responsible for that calamity.  Alternatively, the defeat and capture of Valerian at the battle of Edessa may have been the trigger for the subsequent revolts of Ingenuus, Regalianus, and Postumus.  In any case, Gallienus reacted with great speed.  He left his son Saloninus as Caesar at Cologne, under the supervision of Albanus (or Silvanus) and the military leadership of Postumus.  He then hastily crossed the Balkans, taking with him the new cavalry corps (comitatus) under the command of Aureolus and defeated Ingenuus at Mursa or Sirmium.  The victory must be attributed mainly to the cavalry and its brilliant commander.  Ingenuus was killed by his own guards or committed suicide by drowning himself after the fall of his capital, Sirmium.

Invasion of the Alamanni:
          A major invasion by the Alemanni and other Germanic tribes occurred between 258 and 260 (it is hard to fix the precise date of these events), probably due to the vacuum left by the withdrawal of troops supporting Gallienus in the campaign against Ingenuus.  Franks broke through the lower Rhine, invading Gaul, some reaching as far as southern Spain, sacking Tarraco (modern Tarragona).  The Alamanni invaded, probably through Agri Decumates (an area between the upper Rhine and the upper Danube), likely followed by the Juthungi.  After devastating Germania Superior and Raetia (parts of southern France and Switzerland), they entered Italy, the first invasion of the Italian peninsula, aside from its most remote northern regions, since Hannibal 500 years before.  When invaders reached the outskirts of Rome, they were repelled by an improvised army assembled by the Senate, consisting of local troops (probably praetorian guards) and the strongest of the civilian population.  On their retreat through northern Italy, they were intercepted and defeated in the battle of Mediolanum (near present-day Milan) by Gallienus' army, which had advanced from Gaul, or from the Balkans after dealing with the Franks.  The battle of Mediolanum was decisive, and the Alamanni did not bother the empire for the next ten years. The Juthungi managed to cross the Alps with their valuables and captives from Italy.  An historian in the 19th century suggested that the initiative of the Senate gave rise to jealousy and suspicion by Gallienus, thus contributing to his exclusion of senators from military commands.

The revolt of Regalianus:
          Around the same time, Regalianus, who held some command in the Balkans, was proclaimed Emperor.  The reasons for this are unclear, and the Historia Augusta (almost the sole resource for these events) does not provide a credible story.  It is possible the seizure can be attributed to the discontent of the civilian and military provincials, who felt the defense of the province was being neglected.
          Regalianus held power for some six months and issued coins bearing his image. After some success against the Sarmatians, his revolt ended when the Roxolani invaded Pannonia and killed Regalianus in taking the city of Sirmium.  There is a suggestion that Gallienus invited Roxolani to attack Regalianus, but other historians dismiss the accusation.  It is also suggested that the invasion was finally checked by Gallienus near Verona and that he directed the restoration of the province, probably in person.

Capture of Valerian, revolt of Macrianus:
          In the East, Valerian was confronted with serious troubles. Bands of "Scythai" began a naval raid of Pontus, in the northern part of modern Turkey.  After ravaging the province, they moved south into Cappadocia.  A Roman army from Antioch, under Valerian, tried to intercept them but failed.  According to Zosimus, this army was infected by a plague that gravely weakened it.  In that condition, this army had to repel a new invasion of the province of Mesopotamia by Shapur I, ruler of the Sassanid Empire.  The invasion occurred probably in the early spring of 260.
          The Roman army was defeated at the Battle of Edessa, and Valerian was taken prisoner.  Shapur's army raided Cilicia and Cappadocia (in present-day Turkey), sacking, as Shapur's inscriptions claim, 36 cities.  It took a rally by an officer Callistus (Balista), a fiscal official named Fulvius Macrianus, the remnants of the Roman army in the east, and Odenathus and his Palmyrene horsemen to turn the tide against Shapur.  The Sassanids were driven back, but Macrianus proclaimed his two sons Quietus and Macrianus (sometimes misspelled Macrinus) as emperors.  Coins struck for them in major cities of the East indicate acknowledgement of the usurpation.  The two Macriani left Quietus, Ballista, and, presumably, Odenathus to deal with the Persians while they invaded Europe with an army of 30,000 men, according to the Historia Augusta. At first they met no opposition.
          The Pannonian legions joined the invaders, being resentful of the absence of Gallienus.  He sent his successful commander Aureolus against the rebels, however, and the decisive battle was fought in the spring or early summer of 261, most likely in Illyricum, although Zonaras locates it in Pannonia.  In any case, the army of the usurpers was defeated and surrendered, and their two leaders were killed.
          In the aftermath of the battle, the rebellion of Postumus had already started, so Gallienus had no time to deal with the rest of the usurpers, namely Balista and Quietus.  He came to an agreement with Odenathus, who had just returned from his victorious Persian expedition.  Odenathus received the title of dux Romanorum and besieged the usurpers, who were based at Emesa.  Eventually, the people of Emesa killed Quietus, and Odenathus arrested and executed Balista about November 261.

The revolt of Postumus:
          After the defeat at Edessa, Gallienus lost control over the provinces of Britain, Spain, parts of Germania, and a large part of Gaul when another general, Postumus, declared his own realm (usually known today as the Gallic Empire).  The revolt partially coincided with that of Macrianus in the East.  Gallienus had installed his son Saloninus and his guardian, Silvanus, in Cologne in 258.  Postumus, a general in command of troops on the banks of the Rhine, defeated some raiders and took possession of their spoils. Instead of returning it to the original owners, he preferred to distribute it amongst his soldiers.  When news of this reached Silvanus, he demanded the spoils be sent to him. Postumus made a show of submission, but his soldiers mutinied and proclaimed him Emperor.  Under his command, they besieged Cologne, and after some weeks the defenders of the city opened the gates and handed Saloninus and Silvanus to Postumus, who had them killed.  The dating of these events was long uncertain, but an inscription discovered in 1992 at Augsburg indicates that Postumus had been proclaimed Emperor by September of 260.  Postumus claimed the consulship for himself and one of his associates, Honoratianus, but according to D.S. Potter, he never tried to unseat Gallienus or invade Italy.
          Upon receiving news of the murder of his son, Gallienus began gathering forces to face Postumus.  The invasion of the Macriani forced him to dispatch Aureolus with a large force to oppose them, however, leaving him with insufficient troops to battle Postumus.  After some initial defeats, the army of Aureolus, having defeated the Macriani, rejoined him, and Postumus was expelled.  Aureolus was entrusted with the pursuit and deliberately allowed Postumus to escape and gather new forces.  Gallienus returned in 263 or 265 and surrounded Postumus in an unnamed Gallic city.  During the siege, Gallienus was severely wounded by an arrow and had to leave the field.  The standstill persisted until his later death, and the Gallic Empire remained independent until 274.

The revolt of Aemilianus:
          In 262, the mint in Alexandria started to again issue coins for Gallienus, demonstrating that Egypt had returned to his control after suppressing the revolt of the Macriani.  In spring of 262, the city was wrenched by civil unrest as a result of a new revolt.  The rebel this time was the prefect of Egypt, Lucius Mussius Aemilianus, who had already given support to the revolt of the Macriani.  The correspondence of bishop Dionysius of Alexandria provides a commentary on the background of invasion, civil war, plague, and famine that characterized this age.
          Knowing he could not afford to lose control of the vital Egyptian granaries, Gallienus sent his general Theodotus against Aemilianus, probably by a naval expedition.  The decisive battle probably took place near Thebes, and the result was a clear defeat of Aemilianus.  In the aftermath, Gallienus became Consul three more times in 262, 264, and 266.

Herulian invasions, revolt of Aureolus, conspiracy and death:
          In the years 267–269, Goths and other barbarians invaded the empire in great numbers.  Sources are extremely confused on the dating of these invasions, the participants, and their targets.  Modern historians are not even able to discern with certainty whether there were two or more of these invasions or a single prolonged one.  It seems that, at first, a major naval expedition was led by the Heruli starting from north of the Black Sea and leading in the ravaging of many cities of Greece (among them, Athens and Sparta).  Then another, even more numerous army of invaders started a second naval invasion of the empire.  The Romans defeated the barbarians on sea first. Gallienus' army then won a battle in Thrace, and the Emperor pursued the invaders.  According to some historians, he was the leader of the army who won the great Battle of Naissus, while the majority believes that the victory must be attributed to his successor, Claudius II.
          In 268, at some time before or soon after the battle of Naissus, the authority of Gallienus was challenged by Aureolus, commander of the cavalry stationed in Mediolanum (Milan), who was supposed to keep an eye on Postumus.  Instead, he acted as deputy to Postumus until the very last days of his revolt, when he seems to have claimed the throne for himself.  The decisive battle took place at what is now Pontirolo Nuovo near Milan; Aureolus was clearly defeated and driven back to Milan.  Gallienus laid siege to the city but was murdered during the siege.  There are differing accounts of the murder, but the sources agree that most of Gallienus' officials wanted him dead.  According to the Historia Augusta, an unreliable source compiled long after the events it describes, a conspiracy was led by the commander of the guard Aurelius Heraclianus and Lucius Aurelius Marcianus.  Marcianus's role in the conspiracy is not confirmed by any other ancient source.
          Cecropius, commander of the Dalmatians, spread the word that the forces of Aureolus were leaving the city, and Gallienus left his tent without his bodyguard, only to be struck down by Cecropius.  One version has Claudius selected as Emperor by the conspirators, another chosen by Gallienus on his death bed; the Historia Augusta was concerned to substantiate the descent of the Constantinian dynasty from Claudius, and this may explain its accounts, which do not involve Claudius in the murder.  The other sources (Zosimus i.40 and Zonaras xii.25) report that the conspiracy was organized by Heraclianus, Claudius, and Aurelian.
          According to Aurelius Victor and Zonaras, on hearing the news that Gallienus was dead, the Senate in Rome ordered the execution of his family (including his brother Valerianus and son Marinianus) and their supporters, just before receiving a message from Claudius to spare their lives and deify his predecessor.

Legacy:
          Gallienus was not treated favorably by ancient historians, partly due to the secession of Gaul and Palmyra and his inability to win them back.  According to modern scholar Pat Southern, some historians now see him in a more positive light.  Gallienus produced some useful reforms.

Military reforms:
          He contributed to military history as the first to commission primarily cavalry units, the Comitatenses, that could be dispatched anywhere in the Empire in short order.  This reform arguably created a precedent for the future emperors Diocletian and Constantine I.  The biographer Aurelius Victor reports that Gallienus forbade senators from becoming military commanders.  This policy undermined senatorial power, as more reliable equestrian commanders rose to prominence.  In Southern's view, these reforms and the decline in senatorial influence not only helped Aurelian to salvage the Empire, but they also make Gallienus one of the emperors most responsible for the creation of the Dominate, along with Septimius Severus, Diocletian, and Constantine I.