Yes. In 371 BCE, the Thebans under their general Epamonidas defeated the Spartans at Leuktra, in Boeotia. It was Sparta's biggest defeat in centuries, and the next year (in 370 BCE) the Thebans invaded the Peloponnese and liberated a portion of the helots. Sparta had several different populations of helots, including "local" Lakonian persons and also a large number of "foreign" groups which had long been dominated by Sparta. In 370, the Thebans liberated the helots of Messenia, after which they founded a new city Messene on Mount Ithome, in their ancestral homeland. The helots in the Spartan homeland, however, remained in slavery. They would slowly, over the centuries, gain various aspects of independence under varous reformist rulers.