The name usually given to the committee of thirty aristocrats who at the close of the Peloponnesian War (B.C. 404), and under the protection of the victorious Spartans, undertook the administration of the Athenian government. The chiefs of this body were Critias and Theramenes. They secured a new Senate, put to death their chief political opponents, and installed a Spartan garrison in the Acropolis. A reign of terror ensued which led to a reaction; and presently a body of exiled citizens headed by Thrasybulus marched upon Athens, defeated the troops of the Thirty, and slew Critias. After some delay the Spartan government recognized the status quo and thus permitted the resumption of a democratic government (B.C. 403). (Harpers Dictionary of Classical Antiquities, 1898)