Although it was a short, limited conflict, the First Illyrian War (230-228 BC) is noteworthy as the first time the Roman Republic sent its armies to the eastern shores of the Adriatic. Ever since Rome had gained control of part of the east coast of Italy she had had a direct interest in the control of the straits of Otranto, the narrow entrance to the Adriatic.
The two main powers on the east coast of the Adriatic were Epirus and the Illyrian kingdom of the Ardiaei. Epirus had provided some of Rome’s most dangerous enemies, most famously King Pyrrhus, but in 232 the line of kings had died out, and Epirus had become a federal republic.
The Illyrians, under King Agron, were based on the Dalmatian coast around Split. The Illyrians had always been pirates, preying on the Italian merchants trading in the Adriatic, but they now increased the intensity of their activities, attacking Epirus and capturing the city of Phoenice.
Our main sources (Polybius and Appian) disagree on the exact cause of the First Illyrian War, but only in detail. The basic framework of events saw King Agron attack the island of Issa (modern Vis). Agron died at some point during the siege, and was succeeded by Queen Teuta, regent for his infant son Pinnes (not mentioned by Polybius). Teuta continued the siege. The Romans sent ambassadors to the area, one of whom was killed, triggering the war.
In Polybius the Roman ambassadors, C. and L. Coruncanius, were sent out in response to appeals from the Italian merchants affected by the capture of Phoenice. They had a stormy meeting with Queen Teuta on Issa, and in the aftermath the younger Coruncanius was murdered. Only after this did Queen Teuta send troops south to attack Corcyra (on Corfu). Corcyra was quickly captured, and Demetrius of Pharos placed in command.
In Appian King Agron was responsible for the capture of Corcyra. The Roman ambassadors were sent out in response to an appeal from the people of Issa, but were attacked by Illyrian pirates before they reached the area. One of the Roman ambassadors, again named Coruncanius, was killed, along with the leader of the Issaeans. Only now did Agron die and Teuta take control. The dramatic meeting between the Roman ambassadors never took place. Both of these accounts are perfectly feasible.
The actual events of the war are more certain. Both consuls for 229, Cn. Fulvius Centumalus and L. Postumius Albinus, commanded the army, taking with then their consular armies – 20,000 infantry and 2,000 cavalry supported by 200 warships. Fulvius sailed to Corcyra (Corfu), which was in the hands of the Illyrians. Their commander, Demetrius of Pharos, changed sides, and handed the city over to the Romans.
Fulvius then moved up the coast to Apollonia (now on the Albania coast), already friendly to Rome, where he joined up with Postumius and the Roman army. The local tribes (the Parthini and the Atintanes) submitted to Rome, while Apollonia renewed its alliance.
The combined Roman forces then moved up the coast to Epidamnus, where the Illyrian garrison was quickly expelled. Only then did the Romans move up the coast to Issa (now Vis, off the Croatian coast close to Split). Queen Teuta fled south to the fortress of Rhizon, on the Gulf of Kotor (now just inside Montenegro). This satisfied the Romans. In the autumn of 229 BC Fulvius returned to Rome, taking most of the army with him. Postumius was left to arrange the peace treaty.
Polybius and Appian give different versions of the peace treaty, but the overall Roman aim was clear. At this stage the Republic did not want to expand east of the Adriatic. The Romans wanted to prevent any one power on in the area becoming dominant. Both agree that Queen Teuta had to leave Illyria. Polybius records that she was given a few places, probably around Rhizon. According to Appian Demetrius of Pharos was rewarded with a number of territories, probably close to Pharos, close to Issa. The Illyrians renounced all claims to Corcyra, Pharos, Issa and Epidamnus, and agreed not to sail south of Lissus (now at the northern end of the Albanian coast) with more than two unarmed light ships. Pinnes remained king of the Ardiaei, as an official friend of Rome.
This peace only lasted for ten years before a change in the balance of power brought the Romans back. This time it was their former ally, Demetrius of Pharos, who triggered the fighting. After the end of the First Illyrian War he married Triteuta, the mother of Pinnes, and became regent for the young Pinnes. In 222 Demetrius provided troops for the Macedonian army which defeated the Spartans at Sellasia, not itself a breach of the treaty, but perhaps not the behaviour Rome expected from her official friends. Finally, in 220 BC Demetrius took part in a naval expedition, taking 50 ships around the southern tip of Greece to raid the Cyclades Islands. The Romans saw this as a clear breach of the treaty agreement not to take more than two ships south of Lissus, and in 219 returned to Illyria for the short Second Illyrian War.