After its decisive victory over Athens in 404 BCE, Sparta became the dominant Greek city-state. In 387 BCE, it used its dominance to force the disbandment of the Boeotian League, a Greek sovereign alliance over which Thebes had previously presided, and in 382 BCE imposed a Spartan garrison in Thebes itself. Thereafter, Sparta marched north, capturing Olynthos and forcing dissolution of the Chalcidian League in northeastern Greece. Seizing their moment, the Thebans rebelled, expelling the Spartan garrison. In the ensuing war, the Thebans, under the inspired leadership of Epaminondas and Pelopidas, head of the Sacred Band of elite troops, decisively defeated the Spartans at Leuctra in 371 BCE. They followed up with a series of military campaigns; Pelopidas travelled as far as Thessaly, while Epaminondas conducted a series of campaigns in the Spartans’ Peloponnesian heartlands, culminating with another crushing victory at Mantinea in 362 BCE, where he died on the field of battle.
— OR —