[5] Prior to the creation of the Sacred Band under Gorgidas, the Athenians had helped the Theban exiles retake control of Thebes and the citadel of Cadmea from Sparta.

With the fall of the stockades, they were left with two choices, either to retreat back to the defensible walls of Thebes or to hold their ground and face the Spartans in the open.

[8] In unison, his mercenary hoplites immediately assumed the resting posture—with the spear remaining pointing upwards instead of towards the enemy, and the shield propped against the left knee instead of being hoisted at the shoulders.

[7][12] Xenophon and Diodorus both mention that Agesilaus nevertheless boasted of being the "unchallenged champion", claiming it was a Spartan victory since his enemies declined to accept his invitation to battle.

[14] The account of Polyaenus is almost identical to that of Xenophon and Diodorus but claims instead that Phoebidas survived and implies that the initial Theban retreat was a deliberate ruse by Gorgidas.

Hearing reports that the Spartan garrison in Orchomenus had left for Locris, Pelopidas quickly set out with the Sacred Band and a few cavalry, hoping to capture it in their absence.

He then ordered his cavalry to ride up from the rear and charge while he reformed the Sacred Band into an abnormally dense formation, hoping to at least cut through the numerically superior Spartan lines.

Leaderless and encountering forces equal in discipline and training for the first time in the Sacred Band, the Spartans faltered and opened their ranks, expecting the Thebans to pass through and escape.

[16][19][31] In Plutarch's own words: For in all the great wars there had ever been against Greeks or barbarians, the Spartans were never before beaten by a smaller company than their own; nor, indeed, in a set battle, when their number was equal.

But this battle first taught the other Greeks, that not only Eurotas, or the country between Babyce and Cnacion,[note 3] breeds men of courage and resolution; but that where the youth are ashamed of baseness, and ready to venture in a good cause, where they fly disgrace more than danger, there, wherever it be, are found the bravest and most formidable opponents.Shortly after this, the Athenians initiated the Common Peace of 375 BC (Κοινὴ Εἰρήνη, Koine Eirene) among Greek city-states.

[35][note 4] When news of the uprising at Thebes reached Sparta, an army under Cleombrotus I had been dispatched to subdue the city, but turned back without engaging the Thebans.

[36] At first the Thebans feared facing the Spartans head on, but the conflict gave them much practice and training, and they "had their spirits roused and their bodies thoroughly inured to hardships, and gained experience and courage from their constant struggles".

[47] Immediately following the failure of the peace talks, orders were sent out from Sparta to the Spartan king Cleombrotus, who was at the head of an army in Phocis, commanding him to march directly to Boeotia.

As a consistent advocate of an aggressive policy, Epaminondas wished to fight, and supported by Pelopidas, he managed to swing the vote in favour of battle.

[54] However, the reversing of the position of the elite troops, and an oblique line of attack were innovations; it seems that Epaminondas was therefore responsible for the military tactic of refusing one's flank.

Most importantly, since it constituted a significant proportion of the entire Spartan manpower, 400 of the 700 Spartiates present were killed, a loss that posed a serious threat to Sparta's future war-making abilities.

[67] In Arcadia Epaminondas encouraged the Arcadians to form their proposed league, and to build the new city of Megalopolis (as a center of power opposed to Sparta).

[71] Epaminondas' campaign of 370/369 has been described as an example of "the grand strategy of indirect approach", which was aimed at severing "the economic roots of her [Sparta's] military supremacy.

In order to accomplish all that he wished in the Peloponnesus, Epaminondas had persuaded his fellow Boeotarchs to remain in the field for several months after their term of office had expired.

According to Cornelius Nepos, in his defense Epaminondas merely requested that, if he be executed, the inscription regarding the verdict read: Epaminondas was punished by the Thebans with death, because he obliged them to overthrow the Lacedaemonians at Leuctra, whom, before he was general, none of the Boeotians durst look upon in the field, and because he not only, by one battle, rescued Thebes from destruction, but also secured liberty for all Greece, and brought the power of both people to such a condition, that the Thebans attacked Sparta, and the Lacedaemonians were content if they could save their lives; nor did he cease to prosecute the war, till, after settling Messene, he shut up Sparta with a close siege.

After an abortive attack on Corinth and the arrival of a task force of Iberian mercenaries sent by Dionysius of Syracuse to aid Sparta, the Thebans decided to march home.

The Theban force not only failed to overcome Alexander and his allies, but got into serious difficulties when it tried to withdraw; Epaminondas, serving as a private soldier, succeeded in extricating it.

Epaminondas' acceptance of the Achaean oligarchies roused protests by both the Arcadians and his political rivals, and his settlement was thus shortly reversed: democracies were set up, and the oligarchs exiled.

[79] In 367/365 BC an attempt was made to make a common peace, with the Persian King Artaxerxes II as arbiter and guarantor, through the envoy Philiscus of Abydos.

[80] The Achaemenid king proposed a new peace treaty, this time highly tilted in favour of Thebes, which required Messenia to remain independent and that the Athenian fleet to be dismantled.

[94] Realising that the time allotted for the campaign was drawing to a close, and reasoning that if he departed without defeating the enemies of Tegea, Theban influence in the Peloponnesus would be destroyed, he decided to stake everything on a pitched battle.

[97] Epaminondas then gave the order to advance, catching the enemy off guard, and causing a furious scramble in the Mantinean camp to prepare for battle.

In the clash of infantry, the issue briefly hung in the balance, but then the Theban left-wing broke through the Spartan line, and the entire enemy phalanx was put to flight.

In 377 BC Athens, in preparing for participation in the Spartan–Theban struggle, reorganised its finances and its taxation, inaugurating a system whereby the richer citizens were responsible for the collection of taxes from the less rich.

However, the peace was quickly broken when Sparta attacked Corcyra, enlisting Syracusan help, forcing Athens to come to the island's aid.