Expansionary Athens intervened in disputes outside its territories and sphere - Potidaia and Corcyra, then banned Megara from trading in the Athenian empire.
Sparta, at the behest of the Peloponnesian League which it headed, demanded an end to the ruinous Megara ban, which was refused by an over-confident Athens and war ensued.
Do you want to take the trouble to reword the question so it makes sense.
Presumably an analyis of the Peloponnesian War. Who did it?
Peloponnesian War happened in -431.
There were many Greek wars - what period did you have in mind? You could always try 'The Causes of the Peloponnesian War'.
History of the Peloponnesian War.
This question is incoherent. If you want an answer rewrite it so that it is clear what you are talking about.
Three causes of the Third Century Crisis were Internal civil war, external invasion, and economic disaster.
The draft.
. . . the Peloponnesian War .
The Peloponnesian war
Natural causes, disease, starvation, wounds, other trauma, same then as now.
Aggressivenes of the Athenian empire which interfered in inter-city disputes outside the empire.