The Bellum Batonianum (Latin for War of the Batos) or Great Illyrian Revolt was a military conflict fought in the Roman province of Illyricum in the 1st century AD, in which an alliance of native peoples of the two regions of Illyricum, Dalmatia and Pannonia, revolted against the Romans. The Roman historian Suetonius described the uprising as the most difficult conflict faced by Rome since the Punic Wars two centuries earlier.
The rebellion began among native peoples who had been recruited as auxiliary troops for the Roman army. They were led by Bato the Daesitiate, a chieftain of the Daesitiatae in the central part of present-day Bosnia and Herzegovina, and were later joined by the Breuci, a tribe in Pannonia led by Bato the Breucian. Many other tribes in Illyria also joined the revolt.
Velleius Paterculus called it the Pannonian and Dalmatian War because it involved both regions of Illyricum.
The four-year war lasted from AD 6 to AD 9 and witnessed a large deployment of Roman forces in the province, with whole armies operating across the western Balkans and fighting on more than one front. In AD 8, the Breuci of the Sava valley surrendered, but it took a winter blockade and another season of fighting before the surrender in Dalmatia in AD 9.
Bato the Breucian betrayed Pinnes which later became the Ruler of the Breucians by the Romans.
Background
Illyricum had seen some fighting during the Great Roman Civil War between Julius Caesar and the forces of the Senate led by Pompey several decades earlier. The Romans who lived in some of the coastal towns supported Caesar, while the native peoples largely supported Pompey. Quintus Cornificius, a Caesarian, repulsed Quintus Octavius, a Pompeian. The Dalmatians routed Aulus Gabinius, a Caesarian who had been ordered by Caesar to join Cornificius in Illyricum. The Dalmatians later asked Caesar for a pardon. Caesar demanded a tribute and hostages as compensation, which was standard practice, and sent Publius Vatinius with three legions to enforce this. After Caesar was assassinated in 44 BC, the Dalmatians ignored these demands and routed five of Vatinius' cohorts. With the disruptions caused by further Roman civil wars in the years following, Dalmatian piracy in the Adriatic Sea became a problem again.
In 35 BC, the Iapydes, the northernmost tribe of Dalmatia, carried out raids into northeastern Italy. They attacked Aquileia, and plundered Tergestus (Trieste). From 35 to 33 BC Octavian (who would soon become the emperor Augustus) undertook military campaigns in the region. He defeated the Iapydes and then pushed into southern Pannonia, where he seized the city of Segesta (which later, as a Roman town, was called Siscia). He then turned on the Dalmatians and captured Promona (to the northeast of modern Drniš, Croatia) on the coast, the main city of the Liburnians, which had been seized by the Dalmatians. After that he took the Dalmatian cities of Sunodium and Setovia. He then moved upon the Derbani, who sued for peace. He also destroyed the settlements on the islands of Melite (Mljet) and Melaina Corcyra (Korčula), and deprived the Liburnians of their ships, because all were involved in piracy. Octavian's lieutenants conducted various other operations in the region. Octavian temporarily restored Roman authority in Dalmatia and pushed into southern Pannonia, which had never before been reached by Roman armies.
In 27 BC, the first settlement between Octavian and the Roman Senate formalised Octavian's absolute rule, bestowing the title of Augustus on him and making him the first Roman emperor. It also made arrangements about the provinces of the empire. Most provinces remained senatorial provinces, whose governors were chosen by the Senate from among the senators, while the frontier provinces became imperial provinces, whose governors were appointed by Augustus. The province of Illyricum was constituted out of both Dalmatia and the newly conquered southern Pannonia, and, despite being a frontier province, was designated as a senatorial province.
From 14 BC to 10 BC there were a series of rebellions in southern Pannonia and northern Dalmatia which Roman writers referred to as Bellum Pannonicum (the "Pannonian War"). What little is known about these events comes chiefly from brief accounts by Cassius Dio and a few references by other authors, though there is no information about the causes. The Roman sources had little interest in events in Illyria from the campaigns of Augustus in 35–33 BC to 16 BC. Cassius Dio wrote that in that year the governor of Illyria for 17–16 BC, Publius Silius Nerva, went to fight in the Italian Alps because there were no troops there. Some Pannonians and Noricans entered Istria and pillaged it. Silius Nerva quickly brought the situation under control. At the same time there was a small rebellion in Dalmatia. The Dentheletae, together with the Scordisci, who lived in present-day Serbia at the confluence of the Rivers Savus (Sava), Dravus (Drava), and Danube, attacked the Roman province of Macedonia. A civil war broke out in Thrace. In 15 BC the Romans conquered the Scordisci and annexed Noricum and conducted other operations in other parts of the Alps against the Rhaeti and Vindelici. In 13 BC, Augustus gave Marcus Vipsanius Agrippa, his most important ally, the supreme command in Illyricum. Agrippa found a negotiated solution; however, he died suddenly and the treaty was ignored. Command was then given to Tiberius, who finally defeated the Illyrians. Roman military operations in Illyricum might have started by the time of Marcus Vinicius' governorship in 14–13 BC. The Pannonian War led to Illyricum being redesignated an imperial province.
The war
Indigenous alliance and Roman forces
The Great Illyrian Revolt of AD 6–9 was the only occasion on which the different peoples in the province of Illyricum united against the Romans. The main tribes which contributed to the alliance were the Daesitiatae, Breuci, Dalmatae, Andizetes, Pannonians, Pirustae, Liburnians, and Iapydes (the latter two fighting under an unknown leader). The Dalmatians were led by Bato the Daesitiate, while the Breuci were led by Bato the Breucian, their army commander, and Pinnes, their king. The primary sources of this information are Cassius Dio and Velleius Paterculus. The latter participated in the war but supplied limited information. Suetonius also gave a description of the war: "the most serious of all foreign wars since those with Carthage, which [Tiberius] carried on for three years with fifteen legions and a corresponding force of auxiliaries, amid great difficulties of every kind and the utmost scarcity of supplies."
Suetonius' claim about fifteen legions is known to be incorrect. At one point there were ten legions assembled in Illyricum, but five of them were sent back because this would have created an oversized army. On three occasions the three legions from the Roman province of Moesia were involved in the fighting and on one occasion two legions from the Roman province of Asia were also involved. Through most of the war it was the five legions stationed in Illyricum (three in Pannonia and two in Dalmatia) which were engaged in this war, which covered a very large area. In addition, there were irregular emergency units levied in Italy. The rebels had an efficient military organisation which paralleled that of the Romans, given that they had previously served in Roman-trained auxiliary military units. However, they did not have a regular army and relied largely upon guerrilla tactics, avoiding pitched battles. There were only three major battles in the area of Sirmium (Sremska Mitrovica, in modern Serbia), in nearby northern Moesia, and a number of minor battles in Dalmatia. Much of the Roman war effort instead involved counter-insurgency operations.
AD 6: Outbreak of the rebellion and first year of the war
In AD 6, Tiberius was about to launch the second campaign against the Marcomanni in Germania. Marcus Valerius Messalla Messallinus, the governor of Illyricum, had planned to join him with most of his army, and ordered the local tribes to provide auxiliary contingents. However, when these troops gathered, they rebelled under the leadership of a Daesitiate tribal chieftain named Bato and defeated a Roman force sent against them. Although this war is sometimes described as having been fought by the Daesitiatae and the Breuci only, Cassius Dio identified the forces led by Bato the Daesitiate as Dalmatian, indicating a broader composition. According to Velleius Paterculus, the population of the tribes which rebelled was more than 800,000, and they fielded 200,000 infantry and 9,000 cavalry. Modern scholars cannot be certain of how trustworthy this information is, as ancient historians tended to exaggerate figures. Velleius Paterculus also wrote that the rebels knew Roman military tactics and spoke Latin.
The rebels divided their forces into three parts. One was to invade Italy, which was not far from Nauportus (a Roman fort in present-day Slovenia); one had already entered the Roman province of Macedonia (present-day Greece); and the third fought in their home territories. They executed their plan swiftly, massacring Roman civilians and a sizable veteran contingent who were helpless in this remote area. They seized and pillaged Macedonia, creating general panic in Rome. Augustus, also alarmed, ordered a general levy, and recalled veterans. Rich families were ordered to supply freedmen in proportion to their income, which had not been done since the aftermath of the Battle of Cannae two centuries earlier. Augustus warned that the rebels could reach Rome in ten days if drastic action was not taken. He assigned command of the war to Tiberius. The Roman army was organized into several divisions to evade the united forces of the rebels. Outposts were placed to prevent them from breaking through to Rome, as well as to disrupt their supply lines.
In Cassius Dio's version, at first, Bato the Daesitiate had very few followers. However, once he defeated the Roman force sent against him, more rebels joined him. Then the Breuci, the largest tribe in southern Pannonia, led by a commander also named Bato, marched on Sirmium. Aulus Caecina Severus, the governor of the neighbouring province of Moesia (in modern Serbia, south of the River Sava and west of the River Danube) quickly advanced against them and defeated them near the River Dravus (Drava), but suffered many casualties. Hoping to renew the struggle soon because many Romans had fallen, the Breuci called on their allies to join them. Cassius Dio did not specify whether Severus broke a siege of the city or prevented the enemy from reaching it. The Drava was to the northwest of Sirmium and the Romans from Moesia must have come from the east or the south. Thus, if Caecina Severus did break a siege of Sirmium, he would have pursued the retreating Breuci until they made a last stand. The Dalmatians marched on Salona (in Dalmatia, on the Adriatic coast) but there Bato was defeated and wounded. He sent other men forward who ravaged the coast down to Apollonia. They were defeated in one battle, but won another. Tiberius came from Germania, fearing an invasion of Italy, and sent Valerius Messallinus ahead. Even though Bato was not well, he engaged Tiberius. Tiberius was stronger in open battle, but he was defeated in an ambush. Velleius Paterculus wrote that Messallinus was surrounded by 20,000 men and had only one legion at only half its normal strength (roughly 2,500 men), yet he routed the enemy and was awarded a triumphal decoration (ornamenta triumphalia) and a place in the procession during Tiberius’ Pannonian triumph. Presumably Valerius Messallinus was then sent to defend Salona.