In classical Greece after development of Athens Empireall other Greek polis had come to the point of fear and jealousyespecially Sparta and Corinth. They felt threatened by risingpower of Athens. So the Civil War could not be escaped.

The war was slow to develop.

Let me tell you some of the reasons why Athens engagedinto war. It is very simple. Money. Athenian empire had moneyflowing in from all over its vest territories in forms of tribute.Athens fleet needed large amounts of money to maintain it andto pay salaries. And the fleet was a big chunk of the power thecity had. New ships needed to be added.

Most of the buildings that were build at that timewere financed from the money coming in as a tribute. Just recallParthenon. Also Athens as a center of the empire was always fullof visitors( some coming to the courts to settle their disputes,some for commerce and some came to enjoy the beauty of the town)who spent money on food, housing, pleasures etc. That providedjobs for many Athenians.

Another big reason would be that Athens largely dependedon the import of grain( most of which came from Black sea). Controlof the route from Hellespont to Athens was vital. And you cansee, later on during the war that the only thing ending the warwas when Sparta and its allies were able to put a lock on thegrain road to the Athens. Farther down into the page you wouldbe able to see that possession of this water way was a reasonfor almost all battles at the end of the war.

Perhaps if we were to look at Athens republic wewould notice that the hole regimes well being rested on the moneycoming from the empire. Most off the people were well off becausegovernment was able to aid the poor, provide food in hard times.Athenianswere able to spent their time on the government duties becausetheir were paid for it( which is very unusual for that time sincenon of the sides had gathered such wealth). Because people didn'thave to be rich to govern it provided the base for democracy ofwhich Athenins were very proud.

So as you can see Athens couldn't let the empirefall apart because their own well being was dependent on the countinueof the empire.

The rest of the ancient Greece was in jealousy andfear of the Athens. Sparta-Athens long enemy was seeing a threatto its powers seens Athens tried to move closer and closer intoPeloponesus.The war was unavoidable.

So the Affair of Epidamnus and the Affair of Potidaeawere on their way. First one was when little city of Epidamnuswas seeking help from Corcyra, didn't receive none and went toCorinth.Corcyra saw a threat when Corinthians put their solders in theEpidamnus and tried to go to war, but saw itself alone in circleof enemies so Corcyra wanted to join Athenian empire which itdid. The war started.But Athenians defended like that"Neitherare beginning the war, Peloponnesians, nor are we breaking thetreaty, but those Corcyraens are our allies, and we come to helpthem. So if you want to sail anywhere else, we place no obstacleson your way, but if you are going to sail against Corcyra, orany other of her possessions, we shall our best to stop you."1.