The Peloponnesian War, fought between the cities of the Athenian League and Sparta and her allies, began in 431 B.C. and ended in 404 B.C. Due to the large number of cities embroiled in the conflict, the war spread to Central Greece, the Aegean and Ionian islands, the coastlines of Macedonia, Thrace, Asia Minor and Sicily.

The principal source for the Peloponnesian War is Thucydides’ The History of the Peloponnesian War in eight books, in which, he narrates the events from the beginning of the war until 411/0 B.C., that is, until the Athenian victory at Kynos Sema and the return of Cyzicus to the League. The events from 411/0 B.C. to the end of the war in 404 B.C. are taken up in a later account by Xenophon in the first two books of his Hellenica. From the works of Theopompus of Chios, Cratippus, Hellanicus of Lesbos and other later historians, only fragments survive, while the comedies of Aristophanes contain valuable insights into the internal political situation in Athens. Other important sources for the period include inscriptions, especially treaties between cities.