The Peloponnesian League was led by Sparta and included many of the major cities in the Peloponnese, as well as Argos, Megara, and Sicyon.
The Delian League was led by Athens and included most of the other city-states in the Aegean Sea, as well as some in Ionia and Thrace.
The wars lasted for a total of 27 years, from 431 to 404 BCE. The conflict began when Athens, which was the dominant city-state in Greece at the time, began to expand its power into the Peloponnese. This expansion was seen as a threat by Sparta and its allies, who formed the Peloponnesian League to oppose Athens.
The Peloponnesian Wars were a brutal conflict, with both sides committing acts of violence and destruction. The war also caused widespread economic disruption and loss of life. In the end, Sparta was victorious, and Athens was forced to surrender and accept the terms of the Peloponnesian Peace.