How long did the Peloponnesian War last?

The Peloponnesian War lasted a total of 27 years, from 431 B.C. to 404 B.C. This includes a brief truce period of six years between 421 B.C. and 415 B.C., after which hostilities renewed and the war continued.

The Peloponnesian War was fought between Athens and Sparta, the two most powerful city-states of Greece, alongside their allies. This web of alliances included nearly every city-state in Greece, and because of this, the war affected the entire Greek peninsula. The war ended in 405 B.C. when the Athenian naval fleet was destroyed by Spartans under the command of Lysander, with military aid from the Persians.