Epaminondas (; Ancient Greek: Ἐπαμεινώνδας, romanized: Epameinōndas; 419/411–362 BC) was a Greek general and statesman of the 4th century BC who transformed the Ancient Greek city-state of Thebes, leading it out of Spartan subjugation into a pre-eminent position in Greek politics called the Theban Hegemony. In the process, he broke Spartan military power with his victory at Leuctra and liberated the Messenian helots, a group of Peloponnesian Greeks who had been enslaved under Spartan rule for some 230 years following their defeat in the Second Messenian War ending in 600 BC. Epaminondas reshaped the political map of Greece, fragmented old alliances, created new ones, and supervised the construction of entire cities. He was also militarily influential and invented and implemented several important battlefield tactics, such as the oblique order.
Xenophon, the historian and contemporary, is the main source for Epaminondas's military prowess, and Xenophon describes his admiration for him in his major work Hellenica (book VII, chap. 5, 19). Accordingly, in later centuries the Roman orator Cicero called him "the first man of Greece", and in more recent times Michel de Montaigne judged him one of the three "worthiest and most excellent men" who had ever lived. The changes Epaminondas wrought on the Greek political order did not long outlive him, as the cycle of shifting hegemonies and alliances continued unabated. A mere twenty-seven years after his death, a recalcitrant Thebes was obliterated by Alexander the Great. Thus Epaminondas—who had been praised in his time as an idealist and liberator—is today largely remembered for a decade (371 BC to 362 BC) of campaigning that established a decade long Theban hegemony but also sapped the strength of the great city-states and paved the way for Macedonian hegemony.