The Peloponnesian War (431-404 BC) went down in the history of Ancient Greece as the most significant conflict between Athens and Sparta. There were irreconcilable differences between Sparta and Athens for a long time, mainly due to the various forms of statehood of these large ancient polises. The misunderstandings between the two sides deteriorated because the citizens belonged to different nationalities: the Athenians represented the Ionians, and in turn, the Spartans and their allies were Dorians.
The first phase of the war was called Archidamian War when Sparta repeatedly invaded Attica. Meanwhile, the naval forces of Athens were used to foray the Peloponnese coast to inhibit riots. The first years of the war had a detrimental effect on the economy of Athens. The military potential of the polis was worsened by the rise of the epidemic. The death of the authoritative leader of the Athenian democracy led to political destabilization in the polis. The peace treaty of Nicaea marked the ending of the second war period in 421 BC. However, this treaty was soon underestimated by the renewed hostilities in the Peloponnese. Athens made an attempt to strike Syracuse in 415 BC but disastrously failed. These events ended in the Ionian conflict, which was the final stage of the Peloponnesian war.
The main result of the war was the establishment of the hegemony of Sparta in Greece, a sharp decline in the prestige of not only Athenian democracy but also of the whole of Greece on an international scale. Persia is gradually becoming the master of the situation in international affairs. On the other hand, Greece is entering a protracted period of crisis of the polis system, which led to its subordination to the Macedonian Kingdom and the loss of independence.