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 Achaea n 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 .