The period following the Peloponnesian War was a disaster for Sparta. With victory came the responsibility to govern, so Sparta, as an oligarchy, sought to impose oligarchic governments on those it defeated. But the Spartans did not know how to govern others and many of their appointed governors became tyrants. A “group of thirty” ruled Athens for only a year before it was overthrown and a democracy restored. Elsewhere puppet governments were despised and resisted. Former allies conspired against the Sparta, fearing its intentions, and it wasn’t long before all the defeated Greeks were independent again.
There was also trouble at home. In 398, a plot was discovered which had helots and two Perioeci towns plotting to overthrow the Spartan government. At the same time, the issue of wealth began to bring out the more base instincts of Spartan men; instincts the Lycurgian laws had blocked for so long. As the spoils of the Peloponnesian War reached Sparta, its people began to forget their simple life. Some became wealthy and others coveted that wealth.
As the Oracle had predicted 300 years before, “Greed will be Sparta’s ruin.” Aristotle put it another way, “The Spartans always prevailed in war but were destroyed by empire simply because they did not know how to use the leisure they had won, because they had practiced no more fundamental skill than skill in war”.
Overseeing this Spartan decline was the king Agesilaus, who ruled from 399-360. Agesilaus was an enigma. He was never supposed to rule being the younger brother of the heir, and excelled in the Agoge despite being lame. Rival of Lysander and admired by Xenophon, Agesilaus did his best to protect Spartan honor despite the handicap of an un-Spartan-like mercenary army. Against Boetia in 398, he was severely injured and had to be carried from the battlefield. Later, his many battles against the rising power of Thebes came to nothing and the defeat at Leuctra in 371 proved the Spartan army was finished. The next year, Thebes and her allies invaded the Peloponnese and attacked Sparta itself. Beaten off, they settled for the liberating the Messenians, which ended three hundred years of the helot system.