Eratosthenes of Athens was one of the Thirty Tyrants elected to rule the city of Athens after the Peloponnesian War (431-404 BC).
Having lost the war to the Spartans, the citizens of Athens elected thirty men as oligarchs. These Thirty instituted oppressive and highly exclusionary laws and instituted a political purge against Athenians who had been Spartan informers and collaborators during the long war. Eventually open hostilities between the Thirty and disenfranchised or disaffected Athenian citizens led to a coup d'etat in 403 B.C. that deposed them.
After the removal of the Thirty Tyrants from power, Lysias, one of the ten Attic orators, wrote Against Eratosthenes[1] as an indictment against Eratosthenes for the murder of his brother, Polemarchus. This speech remains one of the world's most famous orations and is identified by some historians as Lysias's personal best.