Social War (220–217 BC)

The Social War or the War of the Allies, was fought from 220 BC to 217 BC between the Hellenic League under Philip V of Macedon and the Aetolian League, Sparta and Elis. It was ended with the Peace of Naupactus.

Origins
Many of the tensions which led to the war were later documented by the Greek historian, Polybius.

The end of the "War of Demetrius,” also called the First Illyian War, in 228 left Aetolia greater in size than ever before. They worked to continue to expand in all directions. Their attempt to expand into Thessaly, where Macedon had recently collapsed, resulted in a violent reaction from Macedon,the first in almost four decades. This created an unceasing suspicion between the two for years to come.

A new alliance emerged between Macedon, Epeiros, Boiotia, and Achaea in the mid 220s, which gave much power and near total control of all Greece to Macedon and the Hellenic League. The Aetolian League began taking defensive measures, being nearly completely encircled by the members of the Hellenic League, or symmachy. Since 229, Antigonus Doson had been guardian and king of Macedon, because the military felt that Philip, the rightful heir, was too young to be an effective ruler. Philip V would begin coming to power as these new areas were entering the Hellenic League.

Aetolia felt very threatened, being the only thing standing in the way of complete Macedonian control of Greece. Ariston helped create a radical new Aetolian policy, actively attempting to prevent the further decay of Aetolia’s international position. The Aetolians were worried about Achaea forming an alliance with the territory of Messenia, in the southwestern part of Peloponnese. If this happened, they would be completely surrounded by their enemies in the Hellenic League. Because of this, Ariston sent expeditionary forces to the city of Phigaleia, in Messenia, to exert more pressure. On the way, these troops pillaged and raided multiple Achaean cities, creating further hostility.

The real cause of problems between the two leagues was not occasional alliances or disputes, but differing policies and methods at a fundamental level. The Hellenic League had a tradition of threats and using violence to achieve their political goals. The Aetolian League, however, was cautious and non-violent in most cases. They had only been in one conflict since 278. Their expansion used diplomacy and politics, instead of violence. The Aetolians aligned themselves with Sparta in 227. This officially marked the end of any alliance between the Aetolian League and the Hellenic League. Sparta wanted this alliance because it would align them with Elis, which would help with their campaign in northwest Achaea. This created more hostile feelings by the Hellenic league towards the Aetolians, feeling as though they had been abandoned by them during this conflict with Sparta.

Philip gathered the members of the Hellenic League in Corinth, where they discussed the problems involving the Aetolian League. Aratus and other members of the league gave lists of complaints, most ranging over a period of many years, dealing with the Aetolians. Philip responded to these complaints with a declaration of war on Aetolia by the symmachy of the Hellenic League. Although acting as though he was responding to the complaints of the league members, Philip was very interested in war to establish himself as a victorious leader and to consolidate the power of Macedonia in Greece. This was exactly what the Aetolian policy since 222 had intended to avoid. Although all of the members of the Hellenic League wanted war with Aetolia, Philip and Achaea were the only people who were interested in waging the actual war. This lack of interest by most of the Hellenic League is most likely a result of the peaceful policies of Aetolia that had been pursued in recent years.

War
In the spring of 220 BC, the Aetolians marched through the middle of Achaea and based themselves in Phigaleia, south of Achaea. The Achaeans were unable to fight this threat on their own, and so Aratus sent representatives to Philip V, asking for the aid of the Symmachy. Macedon was reluctant at first, but after Aetolia became allies with the Illyrians, Macedon's neighbors, Philip marched south to Corinth in the Peloponnese, where he called a council for all his allies. There, they unanimously decided to go the war. He sent a force to Crete to take control from the Aetolians, which was quickly successful, while he returned to Macedon for the winter to prepare for war, including buying the allegiance of the Illyrians and their fleet from the Aetolians. Meanwhile, news of the death of Sparta's king Cleomenes III in Egypt allowed for the rise of a new leader, Lycurgus, under who the Spartans allied with Aetolia.

In the summer of 219 BC Sparta attacked Achaea from the South, Elis attacked from the west, and the Aetolians attacked from the north. By the end of the summer, Achaea was near collapse. Philip the V, meanwhile was marching down the coast west of Aetolia, starting from Epirus and ending in Calydon, where he received news of a pending invasion to Macedon. He returned to his homeland, but the invasion never took place.

In the winter of 219-218 BC Philip secretly took his army to Corinth, and from there down to southern Elis, winning victory after victory against the surprised Eleans, and he retook Phigalea. He then moved back up through Achaea and from there made a campaign against northern Elis and was met with similar success. That summer, he took a fleet to Aetolia and devastated the city of Thermum, in the middle of Aetolian land, and then retreated back westward to land he had previously conquered in the summer of 219 BC. From there he sailed back to Corinth and marched to Sparta, where he made many successful raids before returning to Corinth to deal with soldiers dissatisfied with the low yields of plunder. After a failed attempt at a peace conference, Philip returned home for the winter of 218-217 BC.

In the summer of 217 BC, Aratus managed to provide some new organization of Achaea that enabled them to hold off Elean raids. At the same time Philip V took the city of Thebes in Phthiotic Achaea, but was forced to leave in order to deal with dissatisfied Illyrians who wanted more spoils of war. During this time, he received news that the Romans had been defeated by Hannibal. Deciding to end the Aetolian war in order to focus his attentions on Rome, he called for peace. At Naupactus a treaty was struck, ending the war.

Outcome
As a result of the Social War Philip V became the major military power in Greece.

After 217 Philip turned his attention westward towards the Roman Republic. He took Illyria on the westernmost part of the Balkan Peninsula, allied with Hannibal and Carthage against Rome in 215, and even considered crossing the Adriatic Sea and invading Italy. Philip again defeated the Aetolian League and Rome in the First Macedonian War (214-205) after the two allied against him in 211. The war ended with two different peace treaties; one with the Aetolian League in 206 and one with Rome in 205 called the "Peace of Phoenice" which allowed Philip to keep the land he had taken in Illyria. This war was essentially a renewal of the Social War and ended in the same way with the Aetolian League losing a second war to Philip V and Macedonia.