Sparta entered the Peloponnesian War under the banner of freedom and city-state autonomy, threatened by Athenian imperialism. But, after defeating it, it does the same:it imposes a tribute, governments under its supervision, even garrisons. As early as 413, Thucydides describes it as the power which “now alone exercises its hegemony over all Greece” (VIII, 2, 4).
Sparta therefore changed its policy vis-à-vis Persia, becoming the champion of Pan-Hellenism. First there is the expedition of the Ten Thousand, told by Xenophon in the Anabasis, which fails in 401. In 396, King Agesilaus II is sent with some Spartans, Neodamodes and several thousand allies to drive out Tissaphernes , the satrap of Caria, and protect the Greek cities. Agesilaus's dreams of empire quickly come to an end, for he is recalled from 394, because of the events in Greece:Athens, Thebes, Argos and other cities rise up against Sparta - this is the beginning of the war of Corinth. The coalition was defeated in 394 at Coronea and Nemea, but Sparta lost its maritime hegemony. Meanwhile, the Persians launch a counter-offensive and Athens rebuilds its Long Walls. Threatened, Sparta concludes in 386 the peace of Antalcidas with all the Greeks and Persians.
This peace, protected by the Great King, in fact allowed them to continue their imperialist policy, under the guise of protecting the autonomy of the smallest cities:Sparta forced Argos to give Corinth its independence, or Olynthus to respect the autonomy of the cities of Halkidiki.
In 378, however, the conflict resumed following a Spartan raid on Piraeus. It actually resulted in a peace between Athens and Sparta in 371, both worried about the progress of Thebes. Sparta immediately launches an attack against the Boeotian city, which results in the disaster of Leuctra:Epaminondas destroys the Spartan army led by Cleombrote, and leads a powerful offensive against Sparta itself, which must enlist many Helots to repel the danger of its walls. This is the end of Spartan hegemony.