The Illyro-Roman Wars were a series of wars fought between the Roman Republic and the Ardiaei kingdom. In the First Illyrian War, which lasted from 229 BC to 228 BC, Rome's concern was that the trade across the Adriatic Sea increased after the First Punic War at a time when Ardiaei power increased under queen Teuta. Attacks on trading vessels of Rome's Italic allies by Illyrian pirates and the death of a Roman envoy named Coruncanius on Teuta's orders, prompted the Roman senate to dispatch a Roman army under the command of the consuls Lucius Postumius Albinus and Gnaeus Fulvius Centumalus. Rome expelled Illyrian garrisons from a number of Greek cities including Epidamnus, Apollonia, Corcyra, Pharos and established a protectorate over these Greek towns. The Romans also set up Demetrius of Pharos as a power in Illyria to counterbalance the power of Teuta.
The Second Illyrian War lasted from 220 BC to 219 BC. In 219 BC, the Roman Republic was at war with the Celts of Cisalpine Gaul, and the Second Punic War with Carthage was beginning. These distractions gave Demetrius the time he needed to build a new Illyrian war fleet. Leading this fleet of 90 ships, Demetrius sailed south of Lissus, violating his earlier treaty and starting the war. Demetrius' fleet first attacked Pylos, where he captured 50 ships after several attempts. From Pylos, the fleet sailed to the Cyclades, quelling any resistance that they found on the way. Demetrius foolishly sent a fleet across the Adriatic, and, with the Illyrian forces divided, the fortified city of Dimale was captured by the Roman fleet under Lucius Aemilius Paulus. From Dimale the navy went towards Pharos. The forces of Rome routed the Illyrians and Demetrius fled to Macedon, where he became a trusted councillor at the court of Philip V of Macedon, and remained there until his death at Messene in 214 BC.
In 171 BC, the Illyrian king Gentius was allied with the Romans against the Macedonians. But in 169 BC he changed sides and allied himself with Perseus of Macedon. During the Third Illyrian War, in 168 BC, he arrested two Roman legati and destroyed the cities of Apollonia and Dyrrhachium, which were allied to Rome. He was defeated at Scodra by a Roman force under L. Anicius Gallus, and in 167 BC he was brought to Rome as a captive to participate in Gallus' triumph, after which he was interned at Iguvium.
Prelude
Expansion under Agron
In the second half of the third century BC, the Ardiaei kingdom was transformed into a formidable power under the leadership of Agron. During this time, Agron invaded part of Corcyra, Epidamnos and Pharos in succession, establishing garrisons in them. An invasion towards Epirus was repulsed. The new force disposed of 'the most powerful which could carry 50 soldiers in addition to the rowersforce, both by land and sea, of any of the kings who had reigned in Illyria before him', according to Polybius (2.2). The Illyrians used the lembus, a small and fast warship with a single bank of oars. Raids by sea from the Adriatic and Ionian were probably a familiar threat to the north-western Greeks. What was new was the use of a land army to follow up and profit from the victories gained by the navy. The Greek cities (poleis) on the coast of Illyria were systematically attacked and perhaps already conquered by Agron's forces. Rome answered an appeal from the island of Issa, threatened by Agron, by sending envoys. They never got there. They were attacked en route by Illyrian vessels, and one of them was killed, together with an Issaean ambassador.
That time a number of political events marked the adjacent Greek states. In 234 BC, the royal succession in Epirus came to an end, and a federal republic was instituted. In the south, the western part of Acarnania seceded from this arrangement. Their independence was soon threatened by the Aetolians, who began to occupy territory around the Gulf of Ambracia, including Pyrrhus' old capital, Ambracia, which forced the Epirotes to establish a new center at Phoenice. Besieged at Medion, the Acarnanians sought assistance from Demetrius II of Macedonia, who for the most of his reign had been at war with the Aetolian and Achaean Leagues. In response, the king requested assistance from Agron to relieve the siege.