Illyricum (Roman province)

• 1. Introduction

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  Illyricum was a Roman province created by Augustus in 27 BC to anchor the northeastern Adriatic frontier. It was a vast, rugged territory stretching from the River Drin in modern northern Albania all the way to the Pannonian Plain, covering what are now Albania, Bosnia and Herzegovina, Croatia, Hungary, Kosovo, Montenegro, Serbia, and Slovenia. That is a staggering span of landscape and peoples brought under a single Roman administration.

  The Dinaric Alps ran along the eastern Adriatic coast for 645 kilometres, wide in some places and barren in most. The coastal mountains were poor agricultural land and the islands offshore lacked drinking water. It was geography that bred hardship, and hardship bred fighters. The question the rest of this story answers is how Rome turned that region from a pirate-haunted frontier into the nursery of its own emperors.

• 2. Land of Many Peoples

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  The term Illyrians was used to describe the inhabitants of the area as far back as the late 6th century BC, when Hecataeus of Miletus wrote about them. But the population was never uniform. Dozens of independent tribes lived across the territory, each with its own character.

  In the north, the Pannonian Plain was home to tribes that differed culturally from the Illyrians to their south. Archaeological finds and place names show the Pannonians had connections east and west that set them apart. Celtic tribes moved into the northern part of the region following an invasion at the start of the 4th century BC, and peoples such as the Eravisci, Scordisci, Boii, and Anartii were Celtic in character. Iron mining and production was a significant part of their economy before Rome arrived.

  In the southern interior, the land was more fertile. On the coast, Greek cities had established themselves centuries before Roman legions appeared. Epidamnos, known today as Durrës in Albania, and the island of Pharos, now Stari Grad in Croatia, were Greek foundations long before Rome looked their way. This mixture of Illyrian, Celtic, and Hellenized communities gave the province its complex texture from the start.

• 3. A Century of War

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  Rome's path into Illyricum began with piracy. In 229 BC the Ardiaei tribe, based in what is now Montenegro and northern Albania, had built a powerful fleet and were raiding Roman trade partners. They invaded Epidamnos, struck Corfu, and attacked allied cities in the Peloponnese and Epirus. Rome sent a fleet and forced peace terms. It was the First Illyrian War.

  The Second Illyrian War followed in 219-18 BC after the Ardiaei attacked Roman allies again. Then in 168 BC the Ardiaei joined the wrong side in the Third Macedonian War and were quickly defeated. Rome imposed a tribute equivalent to half the taxes the defeated king had collected, exempting only those who had allied with Rome.

  Decades of smaller campaigns followed. In 156 BC, consul Gaius Marcius Figulus was driven from his camp by the Dalmatae and had to flee to the River Naro. He returned and catapulted burning projectiles into the fortified town of Delminium. His successor, Scipio Nasica Corculum, subdued the Dalmatae in 155 BC. In 129 BC, consul Gaius Sempronius Tuditanus fought the Iapydes in the northern Alps, suffered an initial defeat that was rescued by Decimus Junius Brutus, and was eventually granted a triumph. He commemorated the victory with a dedication to the river god Timavus at Aquileia, two fragments of which were found in 1906.

  In 78-76 BC, the proconsul Gaius Cosconius spent two years reducing a large part of Dalmatia and seizing Salona. Rome's grip on the region was real but never settled.

• 4. Caesar and the Civil Wars

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  In 59 BC the lex Vatinia granted Julius Caesar the proconsulship of Gallia Cisalpina and Illyricum together, with command of three legions based at Aquileia. Illyricum was not yet a formal province in the administrative sense; it was a zone of military command assigned to a powerful commander in a volatile region.

  Aquileia itself had been founded in 180-181 BC as a defensive outpost against the peoples of the eastern Alps. By Caesar's time it was a sizeable town with three legions stationed there because of its strategic role in defending northern Italy. Caesar visited Illyricum in 58 BC to acquaint himself with the country, and again in 54 BC when the Illyrian tribe of the Pirustae raided neighbouring territories. He levied local troops, the Pirustae offered compensation and hostages, and Caesar appointed arbitrators to settle the damages.

  When Caesar's civil war against Pompey began in January 49 BC, Illyricum became a secondary front. Marcus Octavius, one of Pompey's admirals, sailed to Salona with his fleet, failed to win over the Roman inhabitants, besieged the city with five camps, and was eventually stormed by the defenders. He retreated to Dyrrachium as winter came. Caesar's subordinate Aulus Gabinius later marched into Illyricum with fifteen cohorts and 3,000 cavalry by Appian's count, but was routed and lost 2,000 soldiers before retreating to Salona. Gabinius fell ill and died there.

  The Pompeian commander Publius Vatinius eventually cleared the Adriatic in a sharp naval engagement near the island of Tauris. He captured 85 ships and forced Marcus Octavius to flee to Sicily. After Caesar's assassination in 44 BC, the Illyrians sensed the disorder in Rome and ignored the tribute they had promised. One of Caesar's lieutenants, Baebius, was killed in the ensuing fighting. Appian judged that Caesar had postponed dealing firmly with Illyricum for fourteen years because of his Gallic Wars, his civil war, and his plans against Parthia.

• 5. Octavian's Campaigns

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  The campaigns Octavian conducted in Illyricum between 35 and 33 BC were the decisive military operation that made the province possible. In 35 BC he marched against the Iapydes, who had the previous year raided Aquileia, plundered Tergestus, and destroyed Pola. He captured the Iapyde town of Terponus without burning it, hoping for a willing surrender, which came.

  At Metulus, which was the main Iapyde town near modern Ogulin, the defenders numbered 3,000 men. When the siege began to crack their walls they built a second wall inside the first. Octavian threw four bridges across a siege mound to reach the walls. When his soldiers panicked, Octavian crossed the bridge himself alongside his lieutenants Agrippa and Hiero and a single bodyguard. The bridge collapsed under the weight of the men who followed. Octavian was injured in the right leg and both arms. More bridges were built. The defenders eventually surrendered but then tried to fight on; their guards set fire to the council chamber where women and children had been placed. Many of the women killed themselves and their children rather than submit. The city burned completely.

  Turning south, Octavian besieged Segesta, the main town of the Segestani on the River Sava. He wanted the city as a base for future campaigns against the Dacians and Bastarnae across the Danube. After a siege of thirty days he imposed only a fine, placed a garrison of twenty-five cohorts there, and returned to Rome. The city later became the Roman town of Siscia, now Sisak in Croatia.

  In 34 BC Octavian turned on the Dalmatians, who had been in arms since the rout of Gaius Gabinius in 48 BC. Their commander Versus had seized Promona, a mountain stronghold south of modern Knin in Croatia, with up to 12,000 troops. Octavian built a circumvallation wall that reached a length of seven kilometres. After the city fell, a Roman cohort that had broken and fled was punished by decimation; the survivors were made to eat barley instead of wheat for the remainder of the summer. In 33 BC, at Setovia, Octavian was struck by a stone on the knee and had to leave the siege to Titus Statilius while he returned to Rome to take up his consulship. He came back and the Dalmatians surrendered, handing over 700 children as hostages and returning the Roman legion standards taken from Gabinius years before.

• 6. Province and Administration

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  Illyricum became a formal administrative province in 27 BC as part of the settlement by which the Roman senate formalised Augustus's rule. Initially it was a senatorial province, but repeated rebellions showed that a strong military presence was essential. In 11 BC it became an imperial province under the direct control of Augustus, with the governor Publius Cornelius Dolabella administering it from the capital Salona.

  Pliny the Elder left a detailed account of the administrative structure. The coastal area was divided into three judicial districts called conventus juridicus, named after the towns of Scardona, Salona, and Narona. The conventus Salonitanus was subdivided into 5 civitates and 927 decuriae. The Naronitanus had 13 civitates and 540 decuriae. The Scardonitanus held 14 civitates, though no record of its decuriae survives. Pannonia to the north was subdivided into a further 14 civitates and operated as a military district under a prefect who commanded the legions stationed there.

  Dalmatia mattered economically as well. It had gold mines with an imperial bureau in Salona. Its ports connected Rome to the eastern Mediterranean; Dyrrachium in modern Albania was the western terminus of the Via Egnatia, the Roman road stretching east to Byzantium. The capital Salona was protected by military camps at Burnum and Delminium.

  Writing in the winter of 57-58 AD, the Apostle Paul mentioned Illyricum in his Letter to the Romans as the westernmost point of his missionary travels. It was a region where multiple worlds converged. Jewish merchants and artisans connected Salona, Sirmium, and Naissus to Mediterranean and Danubian markets, using Koine Greek in inscriptions and communal life. Their religious communities remained local and decentralised even as the administrative apparatus around them grew more elaborate.

• 7. The Batonian War

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  The Great Illyrian Revolt, known in Latin as the bellum batonianum, broke out in 6 AD and lasted four years. It was named after its two leaders who shared the same name: Bato the Daesitiate and Bato the Breucian. It was the most serious rebellion Rome faced in the region.

  The trigger was military recruitment. The Romans were assembling forces for a campaign against the Marcomanni in Germania and asked the Dalmatian and Pannonian tribes to contribute auxiliary troops. When those forces gathered, they turned on Rome instead. Bato the Daesitiate raised what Cassius Dio described as a Dalmatian force recruited from a wide area of tribes. Bato the Breucian, commander of the largest tribe in southern Pannonia, marched on Sirmium and was defeated by the governor of Moesia, Aulus Caecina Severus. Bato the Daesitiate then marched on Salona but was beaten back by the governor of Illyricum, Marcus Valerius Messalla Messallinus.

  The two Batos joined forces on Mount Alma, which the source identifies as Mount Fruška Gora in Serbia, just north of Sirmium. Augustus warned the Roman senate that the rebels could reach Rome in ten days if nothing was done. Levies were held across Italy. Veterans were recalled to service. Rich families were ordered to contribute freedmen in proportion to their income. Tiberius, the future emperor, took command of the Roman response.

  The war dragged on through scorched earth, famine, and disease. In 8 AD Bato the Breucian overthrew Pinnes, the Breucian king, demanded hostages from Pannonian garrisons, and was then defeated in battle by Bato the Daesitiate and executed. The Pannonians eventually surrendered and laid down their arms at the River Bathinus. By 9 AD the fight was confined to Dalmatia. Two tribes, the Perustae and Daesitiate, who held mountain passes and narrow gorges, were described as nearly exterminated. Tiberius finally cornered Bato the Daesitiate at Adetrium, near Salona, on a rock surrounded by steep ravines. Bato agreed to surrender in exchange for pardon. When Tiberius asked him why his people had rebelled, Bato replied, according to Cassius Dio: "You Romans are to blame for this; for you send as guardians of your flocks, not dogs or shepherds, but wolves."

• 8. Nursery of Emperors

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  John Bury wrote that the importance of Illyricum did not lie in its revenues, but in its men. That judgment proved accurate across centuries. During the Crisis of the Third Century, four emperors were born in Sirmium, modern Sremska Mitrovica in Serbia: Claudius II, who reigned from 268 to 270; Quintillus, who reigned in 270; Aurelian, who reigned from 270 to 275; and Probus, who reigned from 276 to 282. Historians have called this group the Pannonian emperors.

  Diocletian, who reigned from 284 to 305 and reorganised the entire Roman Empire into dioceses and then into a tetrarchy of four co-rulers, was born in Salona in modern Solin, Croatia. Constantine the Great, whose reign from 306 to 337 reshaped both the empire and Christianity, was born in Naissus, modern Niš in Serbia. His father Constantius Chlorus was born in Moesia Superior. The Byzantine emperor Justinian I, who reigned from 527 to 565 and was among the last emperors to employ Latin extensively in imperial law, was born in Tauresium in the province of Dardania, about 20 kilometres southeast of modern Skopje in North Macedonia.

  Diocletian's reforms reorganised the Illyrian territories into two dioceses. The Diocese of Pannonia covered what is now western Hungary, most of Croatia and Bosnia and Herzegovina, and northern Serbia. The Praetorian Prefecture of Illyricum, created in the Constantinian period, stretched across central and southern Serbia, Montenegro, Albania, North Macedonia, most of Greece, and western Bulgaria. Its capital moved over time from Sirmium to Thessalonica, and the prefecture itself survived into the early 7th century. The Roman general Stilicho later tried to bring the region under western Roman control specifically because of its military manpower. Pat Southern described Illyricum as holding the empire together. That claim is easier to accept when you look at the list of men it produced.