The Persians had sacked and burned the temple of Apollo at Abae in 480 BCE, but the famous oracle continues to be consulted—e.g., by the Thebans in 371 BCE before the Battle of Leuctra.

The general war in Greece is ended at a Panhellenic peace conference in 371 BCE (which, in fact, results in another King's Peace), but Sparta and Athens combine to refuse recognition to the Theban federation by insisting that each city of Boeotia should be a separate party to the treaty, while Thebes claims that its federation should be treated as a single unit.

Epaminondas, who is boeotarch (one of the five magistrates of the federation), maintains this position, even when it leads to the exclusion of Thebes from the peace treaty.

The Spartans have an army stationed on Thebes's western frontier, waiting to follow up their diplomatic success by a crushing military attack.

After a breach in the negotiations, signaled by a rhetorical duel between Epaminondas (“a man famous for culture and philosophy,” as his fellow Boeotian Plutarch will describe him half a millennium later) and Agesilaus, who refuses to recognize him as the representative of all Boeotia, the Spartans, led by their other king, Cleombrotus, invade.

Epaminondas is ready with a tactical innovation in the Battle of Leuctra in 371 BCE, twenty days after the peace conference.

Instead of the usual advances of heavily armed infantry drawn up in an equal number of ranks over the whole front, he masses his troops on the left wing, in a further development of the Delium arrangement of 424 BCE, to the unprecedented depth of fifty ranks against an overall Spartan depth of twelve.

This provides a flexible “tail,” or reserve force on the left that can be deployed as the course of the battle suggests.

The decision about whether, when, and how to deploy it will be the general's, whose influence on the outcome of the battle is thus greater than had been usual hitherto.

By placing the best troops on the left, the Thebans aim to knock out the best Spartan troops, who are positioned opposite them, occupying the right wing in the traditional hoplite manner.

Finally, by marching forward obliquely (rather than straightforwardly, as is customary), the Thebans increase the punch administered by this deepened left.

The novelty consists in striking the enemy first at their strongest, instead of their weakest, point, with such crushing force that the attack is irresistible.

The force of the Theban advance overwhelms the Spartans.

The Spartans lose about one thousand men, four hundred of them full Spartan citizens.

The defeat, in which democrats from Argos take part, inflicts such heavy losses on the very limited numbers of the Spartan soldiers that it seriously threatens the possibility of raising another Spartan army.

The Boeotian federation is thus saved.

Thebes, in alliance with Athens, has successfully fought off Sparta and reestablished its traditional leadership in a federation of the cities of Boeotia.

Thespiae had become autonomous as stipulated in the King's Peace of 386 BCE that resolved the Corinthian War, maintaining autonomy until 373 BCE, when the Thebans had subdued the city.

Exiled from Boeotia, the Thespians had arrived in Athens along with the Plataeans seeking aid.

Still, they send a contingent to fight against the Spartans at the Battle of Leuctra in 371 BCE.

The Boeotarch Epaminondas allows the Thespians to withdraw before the battle, along with other Boeotians who nurse a grudge against Thebes.

The city is restored at some later point.

There is a second peace of 371 BCE after Leuctra, this time at Athens.

It is disputed whether Sparta participated, but it is certain that the Thebans were again excluded.

It is also certain that the peace included undertakings to accept “the decrees of the Athenian allies”—a possible reference to the Second Athenian Confederacy and in any case a further strengthening of Athens' position.

In addition, a new power had arisen in Thessaly, that of the energetic Jason of Pherae, an ally of Thebes.

Sparta's inability to respond to local Thessalian appeals against Jason proves that Spartan ambition in central Greece has finally ended.

A military despot on the Dionysius model, he is assassinated in 370; his eventual aims remain an enigma.

Diodorus Siculus tells us that upon the assassination of Jason, his brother Polydorus ruled for a year, but he was then poisoned by Alexander, another brother.

However, according to Xenophon, Polydorus was murdered by his brother Polyphron, who was, in turn, murdered by his nephew Alexander—son of Jason, in 369 BCE.

Plutarch relates that Alexander worshiped the spear he slew his uncle with as if it were a god.

Alexander governs tyrannically, and according to Diodorus, differently from the former rulers, but Polyphron, at least, seems to have set him the example.

The states of Thessaly, which had previously acknowledged the authority of Jason of Pherae, were not so willing to submit to Alexander the tyrant, (especially the old family of the Aleuadae of Larissa, who had most reason to fear him).

Therefore they apply for help from the young Alexander II of Macedon.

Plato advances many of his principal ideas concerning government and justice in his Republic, written about 370.

Set forth as a debate between Socrates and five other speakers, the work describes an ideal state (based on Sparta), which Plato argues should be ruled by philosopher-kings.

Plato regards the philosopher as best suited to govern because he perceives the natural harmony between the principles of justice that govern the state and those that rule the individual.

Plato presents his concept of the ideal Forms in Book Seven’s allegory of the Cave—the world of illusion and ignorance—beyond which only the philosopher has ventured to perceive the ideal models of justice.

His doctrine of Forms postulates a realm of pure ideas, or essences, that exists above and beyond the illusory sensory world.

Plato's nephew and disciple, Speusippus, around 370 devises an encyclopedia-like work to record permanently the master's lectures on mathematics, natural history, and philosophy.

Cotys, king of Thrace, opposes Ariobarzanes of Phrygia, and his ally, the Athenians, on their revolt  from Persian rule.

He goes to war with the Athenians soon after for the possession of the Thracian Chersonese.

Athens, now that she cannot trust Iphicrates to protect her interests, organizes a rebellion against Cotys, led by his treasurer Miltokythes.

Iphicrates, having retired to Thrace, fights also for the Thracian king against Athens: with the help of Charidemus, a Greek mercenary leader from Euboea who had served under Iphicrates at Amphipolis, he bribes the Athenian military and naval commanders to suppress the rebellion.

Charidemus, captured by the Athenians, is taken into their service and receives their citizenship, but in 362, he is discharged.

After participating in the revolt of satraps in Persia, he again joins Cotys, and returns to Athens in 361 with a treaty from Cotys, proclaiming him an ally.

Cotys has successfully retained his kingdom.

By 359 BCE, Cotys controls the whole Chersonese peninsula.

During the same year he makes an alliance with the new Macedonian king, Philip II.

In 358 BCE, he is murdered by two of Plato’s students from Aenus, Python and Heraclides.

Thought previously as advisers to the King, they murdered him during a feast in his palace, under the pretext that he had wronged their father.

Upon their return to Athens, they are proclaimed honorary citizens and rewarded with gold wreaths.

On Cotys' murder, Charidemus becomes guardian to the dead king's young son, Cersobleptes, in conjunction with Berisades and Amadocus II, who are probably his brothers.

He is very young at this time, and the whole management of his affairs is assumed by Charidemus, who is connected by marriage with the royal family.

The area controlled by Cersobleptes is east of the river Hebrus.

The Odrysian empire splits itself in three smaller kingdoms, of which this one, with the capital at Seuthopolis, is to survive the longest.

The Middle East: 369–358 BCE

Revolts and Realignments within the Persian Empire

This era in the Persian Empire under Artaxerxes II is marked by continued political turbulence, with satraps frequently challenging central authority. Following the resolution of Evagoras' rebellion in Cyprus, unrest flares again in the empire’s western provinces, notably in Anatolia, Phoenicia, and Egypt. These regions are consistently restive, driven by local ambitions, dissatisfaction with Persian rule, and encouragement from external powers, particularly Greek city-states.

In Egypt, Pharaoh Nectanebo I (reigned 380–362 BCE) strengthens defenses against Persian reconquest attempts and sponsors revolts in Syria and Palestine to divert Persian resources. This results in prolonged but indecisive warfare that weakens Persian control in the Levant.

Meanwhile, in Anatolia, Persian satraps continue to assert semi-autonomous authority, often forming informal alliances with influential Greek states. The Persian Empire, though still powerful, increasingly appears strained by internal dissent and external pressures, foreshadowing greater difficulties in maintaining cohesion over its extensive territories.

Despite these tensions, Artaxerxes II successfully manages the immediate crises through strategic use of diplomacy and selective military interventions. The empire remains intact, though clearly demonstrating vulnerabilities that future opponents, such as the rising kingdom of Macedon, will later exploit.