The Spartan terms for peace for the end of the Peloponnesean War dictated that the Athenians tear down their long walls (connecting Peiraieus to Athens), surrender all ships but twelve, allow their exiles to return, have the same friends and enemies as the Spartans, and follow the Spartans as their leaders. There were Spartan allies who wanted Athens razed, but the Ephors said no. They believed that no one should destroy a people who had given so much to the Greek culture.
Once the long walls were destroyed the Athenian assembly was asked to choose thirty men to rewrite their laws. The names of the chosen were Polychares, Kritias, Melobios, Hippolochos, Eucleides, Hieron, Mnesilochos, Chremon, Theramenes, Aresias, Diokles, Phaedrias, Chaireleos, Anaitios, Peison, Sophocles, Eratosthenes, Charicles, Onomacles, Theognis, Aeschines, Theogenes, Cleomedes, Erasistratos, Pheidon, Dracontides, Eumathes, Aristoteles, Hippomachos, and Mnesitheides. Of these men, twenty-five are obscure, three are known only by anecdote, and two were major players in the drama that would follow.
As Xenophon tells us, the rewriting of the laws bogged down almost immediately because most of The Thirty had another agenda – retribution. All agreed to hunt down and execute traitors from the Peloponnesean War, but they also schemed to take power permanently. They asked Sparta to provide a garrison to protect them until the new constitution could be established and then, with the garrison in place under Kallibios, The Thirty began drawing up a list of those who would oppose their absolute power, in order to have them killed.
Theramenes, who had been to Sparta as part of the negotiation team to end the war, opposed this step as unlawful and immoral. He demanded that The Thirty allow more participation in the Athenian government so they responded by drawing up a list of three thousand who would participate in the government. All other Athenians were disarmed and excluded from the system. Now The Thirty began their reign of terror against the rich and all who opposed them.
Kritias, the unofficial leader of the group, was again opposed by Theramenes, who was denounced and forced to take poison. This caused a general revolt that saw a rebel group located in Peiraieus defeat the army of The Thirty killing Kritias and Hippomachos. The remainder of The Thirty retreated to Eleusis and begged for Spartan help.
This time fortune favored the oppressed. Lysander, the Spartan Admiral sympathetic to The Thirty, was preparing to defend their interests when the Spartan king Pausanias overruled his attack fearing that Lysander was becoming too powerful. He also believed that blind support for the ultra-conservatives was a mistake. After a skirmish with the rebels, Pausanias decided to use them to broker a peace with Athens. In the end a new government was formed and The Thirty were banished to Eleusis.
One year after the Spartan/Athenian treaty created The Thirty, it was gone – destroyed by its oppression and ruthlessness. This same model had been employed by the Spartans in other Poleis, typically with a ten man oligarchy, but the notion of a Spartan garrison backing a group of local henchman did not go down well with the oppressed any place where it was tried.
When their war with Persia broke out in 400 B.C. the Spartans became distracted from their efforts to control Attica and, by 395 B.C, Athens had re-built the long walls, re-occupied the Aegean Islands, and launched a new navy.
One can certainly understand the Spartan position. They wanted to avoid a continuation of The Thirty year Peloponnesean War by keeping their adversaries under control. The problem was their use of a political model which worked for them but not in cultures used to wider public participation. The Spartans knew how to win wars, but not how to govern those they conquered.