Octavian (the future emperor Augustus) made his first attempt to occupy the northern Illyrian region (roughly modern Croatia) from 35 B.C. to 33 B.C. This conflict came shortly after he achieved a definitive victory over Sextus Pompey in Roman Sicily and before the decisive clash with his fellow triumvir, Mark Antony, in Roman Greece and Ptolemaic Egypt. Octavian was wounded in battle during the first conflict. However, the triumph for his victories was delayed and celebrated only after the defeat of Mark Antony and Cleopatra.
In the course of the Illyrian War, Octavian conquered (in addition to some less serious foes) the Iapodes and Delmatae tribes, and parts of Pannonia around Segestica/Siscia. However, the majority of the future provinces of Pannonia and Dalmatia were subdued by Tiberius during his Pannonian War (12–9 BC) and Pannonian-Dalmatian Rebellion (AD 6–9). These conflicts were initiated by preparations for war against Maroboduus, particularly through the recruitment of soldiers in Illyricum.
Historical context
When Caesar was killed (Ides of March, 44 BC), the Dalmatians rebelled again, thinking that Roman power resided in the dictator who had just died, and they objected to paying tribute to the governor of Illyricum, Publius Vatinius. The latter, although he attempted to use force against them, was attacked and suffered the annihilation of as many as five of his cohorts. At the same time, the senate of Rome determined to transfer its army, along with the province of Macedonia and Illyricum to one of Caesar's assassins, Marcus Junius Brutus. Vatinius was, therefore, forced to fall back to Dyrrhachium, which was located in Macedonia, where the then governor, Gaius Antonius, brother of Mark, was also in serious trouble under Brutus' attack. A large part of Vatinius's forces defected and sided with Brutus, who then laid siege to Gaius Antonius at Apollonia. The fact, however, that they had to defend themselves against the armies of the triumvirs, Mark Antony and Octavian, who wanted to avenge Caesar's death and were gathering the necessary forces for the decisive clash, which later took place at Philippi (42 B.C. BC), did not allow the Romans to deal with the Illyrian rebels, although Vatinius was granted the triumph de Illyrico on July 31, 42 BC.
In 40 BCE, following the defeat of Caesar's assassins and the creation of a second triumvirate, Octavian and Antony divided the Illyrian area with the pact of Brindisi. Octavian received the northern part and the entire Roman West (apart from proconsular Africa, left to Marcus Aemilius Lepidus), and Antony the southern part with Macedonia, along with the entire Roman East. The demarcation line was placed where the old Illyrian capital of Scodra was located. In 39 BC, Gaius Asinius Pollio, to whom Antony had entrusted the government of the province of Macedon as proconsul, penetrated the territory of the Parthini, leading a military campaign that brought the Romans final victory in the area around Dyrrachium, so much so that it earned him a triumph on October 28 of the same 39 BC. Wilkies argues that these operations were short-lived and conducted to keep the legions active, as opposed to leaving them idle in their winter quarters, as well as intended to punish the alliance the Parthini had previously concluded with Brutus. According to other Latin writers, however, the operations were conducted against the Delmatae, and at the end of the war weapons, flocks, and lands were confiscated from them, and Pollio was given the victorious title of Delmaticus. Moreover, Wilkes does not believe that Pollio could have fought against the Delmatae, as they were too far from the province of Macedonia, which belonged to Mark Antony's sphere of influence; much closer was Illyricum, which belonged to Octavian.
Casus belli
While Syme believed that Illyricum was the most important strategic region of the Roman Empire, Wilkes believes that it was necessary for Octavian to secure control of the road that connected northern Italy (Gallia cisalpina) with the middle/lower Danube, to the eastern frontier. This route passed through important (and future) Roman administrative/military centers such as Siscia and Sirmium on the Sava, Singidunum on the Danube, Serdica in Thrace, all the way to Byzantium (the future Constantinople). Hence, if the entire area south of the Danube was to be secured, the Empire had to put in place a vast strategic plan contemplating the conquest of the whole of Illyricum, far more decisive than the conquest of Germania Magna.
- The first objective of these campaigns was - Velleius Paterculus and Cassius Dio report it - to make sure that these military operations would be useful for Octavian's legionaries to practice against a real enemy, and not "slumber in idleness," in view of the far more decisive and forthcoming war against Antony, given the growing disagreements between the two.
- Another goal, certainly no less significant, was to defend the northeastern Alpine sector of the attacks of neighboring peoples and their failure to pay tribute owed to the Romans. The peoples who were creating the greatest problems were the Iapodes, the Segestans, the Dalmatians (Delmatae), the Daesitiates (Daesitiatae), the Liburnians, and the Pannonians. The Iapodes, defined by Appian as a strong and savage tribe, repelled the Romans twice within the last twenty years (55-36 B.C.), and invaded their territories as far as Aquileia, managing to sack the Roman colony of Tergeste (Trieste).
- Added to these populations from the Illyrian-Pannonian area was the risk of a possible attack by the Dacians, although the previous kingdom of Burebista had weakened and split into several kingdoms after the demise of the great Dacian ruler (44 BCE). Moreover, plans for a conquest of Dacia had already been designed earlier by Caesar, shortly before his death, a project that Octavian strongly wanted to bring to fruition in the footsteps of what his adoptive father had left unfinished.
- However, the main strategic reason was to aim at joining the two proconsular provinces of Illyricum and Macedonia, in a vast area that would carry Roman rule as far as the Danube, and be placed under the control of a number of Augustan legates, under whose command 6-7 legions and related auxiliary units were then placed.
Forces in the field
Romans
Based on Gonzales' assumptions, the legions involved were almost certainly Legio XIII Gemina, XIV Gemina, and XV Apollinaris, all of which had been formed earlier by Caesar (XIII, XIV, and XV).
In addition, a fleet of populations allied with the Romans (Taurisci and Norici) was also used, which sailed along the Drava to the Danube and then up the Sava. It was placed under the leadership of a certain Menodorus (Menas).
During the preparations for the military campaign it is known from Cassius Dio that, when some of the soldiers who had been discharged mutinied, since they had not received their severance pay, and asked to return to service in the ranks of Octavian's army, he gathered them into a single legion, so that they would be separated from the others and it would be difficult for them to engage the other legionary units in case they wanted to rebel again. By doing so, this unit could be disbanded with great speed. In fact, when they no longer proved as disciplined as before, he sent some of the older ones as colonists to Gaul, thinking that this reward would give them good hope for the future and silence them. However, since they continued to be insubordinate, he had them all gathered together as if they had been summoned for some other purpose, surrounded them with the rest of the army, took away their weapons, and dismissed them permanently. In this way they understood the determination and strength of their commander. Eventually their continued pleas and requests for forgiveness caused Octavian to pardon them and reintegrate them back into the ranks of his army, partly because he needed useful soldiers at least for so many different tasks, fearing that Antony, with whom he was now at loggerheads, would appropriate them.
Campaigns
Appian of Alexandria recounts that Octavian subdued numerous populations of the Illyrian area such as the Oxyaei, Perthoneatae, Bathiatae, Taulantii, Cambaei, Cinambri, Meromenni, and Pyrissaei in a (first) military campaign. It seems that these populations formed a compact group in the far southwestern part of Illyricum. Some of them survived later as communities of the Conventus iuridicus of Narona. They were therefore settled between the Narenta and Drilon rivers.
In a later effort, he also defeated Carni and Taurisci, who were located north of Aquileia; then Interphrurini, Docleatae (near the city of Doclea), Naresii (from the Narenta River valley) and Glintidiones, peoples who inhabited the southern part of Illyricum, south of the Delmatae. From these peoples he obtained the tributes they had previously been unwilling to pay. Once these peoples had been conquered, the Hippasini (a name completely unknown and whose whereabouts are unknown) and the Bessi (a population of Thrace, a long way from the theater of Octavian's military campaigns), again according to Appian, were overcome by fear and surrendered. Others, on the other hand, who had previously revolted, such as the Meliteni of Melita and the Corcyreni of Corcyra Melaina, who inhabited the islands and practiced piracy, were attacked and subdued by the fleet that came from Sicily, while the young men were put to death and the rest of the population sold as slaves. He finally had all the ships surrendered by the Liburnians so as to prevent them from practicing piracy again in the future.
35 BC campaign
The first campaign moved from the city of Aquileia, where the "headquarters" of some legions were located, and from the Liburnian port of Senia, then crossed the Velebit and entered the plain of the Lika River. Octavian led experienced military people with him, such as his fraternal friend Marcus Vipsanius Agrippa, trusted legate Gaius Fufius Geminus, the former suffect consul Titus Statilius Taurus, and military tribune Marcus Valerius Messalla Corvinus (certainly in 35 B.C.).
Appian relates that Octavian initially advanced against the Iapodes, via a steep and difficult road, especially since the enemy had obstructed its path, cutting down numerous trees. The route of march that Wilkes hypothesizes is the one that led from Tergeste to Senia (Senj), and then penetrated through the chain of mountains of the Great Chapel. In fact, as soon as the Roman armies penetrated into enemy territory, the indigenous peoples took refuge in the nearby forests. The Moentini of Monetium (Brinje), the Avendeatae of Avendo (Crkvina, near Otočac), two tribes of the Iapodes, surrendered as soon as Octavian approached their territories. The Arupini of Arupium (Prozor), on the other hand, who were the most numerous and fearsome warriors among the Iapodes, when the Roman armies approached, fled into the forests abandoning their towns and villages. However, Octavian avoided burning those places, hoping that they would surrender so that they could reoccupy them, which eventually happened. Before surrendering, however, they prepared to ambush the army, which was advancing into their territory. Octavian, who had expected such behavior, sent contingents to occupy some peaks that lay on the flanks of the road the rest of the legions were traveling. And when his soldiers tried to move the logs brought down by the enemy, the Iapodes suddenly jumped out of the bush and engaged in battle, wounding several legionaries. Eventually the Romans prevailed, killing many of the enemies, partly thanks to the arrival of reinforcements from the heights, those whom Octavian had taken care to have occupied earlier, and who had followed the main column of their comrades closely down the valley.
From there Octavian divided his army into several marching columns (one to cover the central valley and two to parallel the surrounding heights), and advanced eastward in the direction of the Colapis River and across the Dinaric Alps (in the area of Mala Kapela, Plješivica). The region he was crossing was thickly forested and mountainous, with rare clearings, while the few Illyrian fortresses were perched on hilltops. The rest of the Iapodes returned, therefore, to take refuge in the forests, abandoning their main city, whose name was Terponus, which Octavian occupied shortly afterwards but did not burn it, hoping that they would surrender. And so they did shortly thereafter.