According to the ancient Greek historian Polybius, an important factor in Philip's decision to take advantage of this opportunity was the influence of Demetrius of Pharos.

Perhaps seeing a chance to recover his kingdom, Demetrius immediately advised the young king to make peace with the Aetolians and turn his attentions toward Illyria and Italy.

Polybius quotes Demetrius as saying: For Greece is already entirely obedient to you, and will remain so: the Achaeans from genuine affection; the Aetolians from the terror which their disasters in the present war have inspired them.

[5] Polybius quotes the Aetolian Agelaus of Naupactus as having given the following speech[6] in favor of peace: The best thing of all is that the Greeks should not go to war with each other at all, but give the gods hearty thanks if by all speaking with one voice, and joining hands like people crossing a stream, they may be able to repel the attacks of barbarians and save themselves and their cities.

But if this is altogether impossible, in the present juncture at least we ought to be unanimous and on our guard, when we see the bloated armaments and the vast proportions assumed by the war in the west.

[7]Philip spent the winter of 217–216 BC building a fleet of 100 warships and training men to row them and, according to Polybius, it was a practice that "hardly any Macedonian king had ever done before".

Polybius speaks of "panic" and "disorder" to describe the fleet's hasty retreat and says that, in fact, the Romans had sent only a squadron of ten ships and that because of "inconsiderate alarm", Philip had missed his best chance to achieve his aims in Illyria, returning to Macedon, "without loss indeed, but with considerable dishonour".

In the account given by Livy,[21] Laevinus, hearing that Apollonia was under siege, sent 2000 men under the command of Quintus Naevius Crista, to the mouth of the river.

Escaping to his ships in the river, Philip made his way over the mountains and back to Macedonia, having burned his fleet and leaving behind many thousands of his men that had died or been taken prisoner, along with all of his armies' possessions.

[24] However, the loss of his fleet meant that Philip would now be dependent on Carthage for passage to and from Italy, making the prospect of invasion considerably less appealing.

Laevinus pointed out the recent capture of Syracuse and Capua in the war against Carthage as evidence of Rome's rising fortunes and offered to ally with them against the Macedonians.

A treaty was signed whereby the Aetolians would conduct operations on land, the Romans at sea and Rome would keep any slaves and other booty taken and Aetolia would receive control of any territory acquired.

Another provision of the treaty allowed for the inclusion of certain allies of the League: Elis, Sparta, Messenia and Attalus I of Pergamon, as well as two Roman clients, the Illyrians Pleuratus and Scerdilaidas.

Desperate and overmatched, but determined to resist, the Acarnanians sent their women, children and old men to seek refuge in Epirus and the rest marched to the frontier, having sworn an oath to fight to the death, "invoking a terrible curse" upon any who were forsworn.

He invested and took Echinus, using extensive siegeworks, having beaten back an attempt to relieve the town by the Aetolian strategos Dorimachus and the Roman fleet, now commanded by the proconsul Publius Sulpicius Galba.

Sulpicius and Dorimachus took Aegina, an island in the Saronic Gulf, which the Aetolians sold to Attalus, the Pergamene king, for thirty talents, and which he was to use as his base of operations against Macedon in the Aegean Sea.

He also heard that Attalus had been elected one of the two supreme commanders of the Aetolian League, as well as rumors that he intended to crossover the Aegean from Asia Minor.

From Lamia, Philip went to Phalara where he met representatives from the neutral states of Egypt, Rhodes, Athens and Chios who were trying to end the war.

The Aetolian representatives, emboldened by these events, at once demanded that Philip return Pylos to the Messenians, Atintania to Rome and the Ardiaei to Scerdilaidas and Pleuratus.

"Indignant", Philip quit the negotiations telling the assembly that they "might bear him witness that whilst he was seeking a basis for peace, the other side were determined to find a pretext for war".

Philip then joined Cycliadas, the Achaean general, near Dyme for a joint attack on the city of Elis, the main Aetolian base of operations against Achaea.

[39] In 208 BC, the combined fleet of thirty-five Pergamene and twenty-five Roman ships failed to take Lemnos, but occupied and plundered the countryside of the island of Peparethos (Skopelos), both Macedonian possessions.

[40] Attalus and Sulpicius then attended a meeting in Heraclea Trachinia of the Council of the Aetolians, which included representatives from Egypt and Rhodes, who were continuing to try to arrange a peace.

[42] He distributed his commanders and forces and set up a system of beacon fires at various high places to communicate instantly any enemy movements.

After leaving Heraclea, Attalus and Sulpicius sacked both Oreus on the northern coast of Euboea, and Opus, the chief city of eastern Locris.

Sulpicius returned to Aegina, so free from the pressure of the combined Roman and Pergamene fleets, Philip was able to resume the offensive against the Aetolians.

[46] The neutral trading powers were still trying to arrange a peace and, at Elateia, Philip met with the same would-be peacemakers from Egypt and Rhodes who had been at the previous meeting in Heraclea, and again in the spring of 207 BC, but to no avail.

The following spring[49] the Romans sent the censor Publius Sempronius Tuditanus with 35 ships and 11,000 men to Dyrrachium in Illyria, where he incited the Parthini to revolt and laid siege to Dimale.