2nd Stage of the Peloponnesian War from 421-413
Corinth forms coalitions against Athens. Alcibiades stirs up trouble and is exiled. Betrays Athens to Sparta. Both sides seek the alliance of Argos but in the Battle of Mantinea she loses most of her military and becomes an Athenian ally.
415-413 - Athenian expedition to Syracuse. Sicily.
3rd Stage of the Peloponnesian War from 413-404
Under the advice of Alcibiades, Sparta invades Attica. Athens continues to send ships and men to Sicily even though it is disastrous. Athens, which had started the war with the advantage in naval battle, loses this advantage to the Corinthians and Syracusans. Sparta then used Persian gold from Cyrus to build her fleet and destroys the Athenian fleet at the Battle of Aegosotami.