Alexander II of Macedon had successfully gained control of Larissa and several other cities but, betraying a promise he had made, had put garrisons in them, provoking a hostile reaction from Thebes, the leading military power in Greece at this time.

The Theban general Pelopidas, after driving the Macedonians from Thessaly, now neutralizes Alexander by favoring the ambitions of Alexander's brother-in-law Ptolemy of Aloros, and forces Alexander to abandon his alliance with Athens in favor of Thebes.

As part of this new alliance, Alexander is compelled to hand over hostages, including his younger brother Philip.

At the instigation of Ptolemy, Alexander is assassinated during a festival.

Although Alexander's brother Perdiccas III becomes the next king, he is under age, and Ptolemy is appointed regent.

On the arrival of Pelopidas at Larissa, whence according to Diodorus, he dislodged the Macedonian garrison, Alexander of Pherae presents himself and offers submission.

When Pelopidas expresses indignation at the tales of Alexander's profligacy and cruelty, the tyrant takes alarm and flees.

These events appear to refer to the early part of the year 368 BCE.

Pelopidas in the summer of this year is again sent into Thessaly, in consequence of fresh complaints against Alexander.

Accompanied by Ismenias, he goes merely as a negotiator, without any military force, and is seized by Alexander and thrown into prison. (The scholar William Mitford suggested that Pelopidas was taken prisoner in battle, but the language of Demosthenes hardly supports such an inference.)

The Thebans send a large army into Thessaly to rescue Pelopidas, but they cannot keep the field against the superior cavalry of Alexander, who, aided by auxiliaries from Athens, pursues them with great slaughter.

The destruction of the whole Theban army is said to only have been averted by the ability of Epaminondas, who is serving in the campaign, but not as general.

Epaminondas leads a second successful invasion of the Peloponnese in 369-368 BCE, gaining further allies for Boeotia.

Sicyon, which had joined the Peloponnesian League after the fall of the Orthagorid tyranny, has remained a loyal ally of Sparta for about a century and a half; its plentiful coinage attests to its prosperity in this period.

Theban intervention in 369 BCE or 368 BCE leads, however, to intermittent civil strife and tyrannies.

Syracuse, despite the mandatory payments to Carthage, prospers during the long reign of Dionysius, a patron of the arts who has erected many buildings and has made his fleet the most powerful in the Mediterranean.

His troops, in support of Sparta, continue in the early 360s BCE to operate against Thebes.

Dionysius launches a fourth war against Carthage, scoring victories until …

…Dionysius dies during the blockade of Lilybaeum (present Marsala), which permits a Carthaginian victory.

The loss of Messene has crippled Sparta economically; in particular, Sparta no longer has a helot population to provide the economic surplus necessary for its military life-style.

The combined impact of Leuctra, Megalopolis, and Messene is, however, not immediately obvious; in the “Tearless Battle” of 368 (or 367), the Spartan army, commanded by Agesilaus' son Archidamus, still manages to win a victory over a force of Arcadians, but Sparta is no longer a leading power.

Affairs in Thessaly and Arcadia are temporarily stalemated by 367, and a peace conference is held at Susa, inside the Persian empire.

Pelopidas asks that Sparta be made to give up Messenia formally and (more important, in view of Sparta's relative impotence at this time) that Athens be requested to give up its fleet.

Alexander of Pherae carries out a massacre of the citizens of Skotoussa in 367 BCE .

Epaminondas, appointed general for his performance against Alexander in battle, has resulted in his reelection as boeotarch.

Epaminondas now returns to Thessaly with a large army, resulting, according to Plutarch, in a three-year truce and the release of prisoners, including Pelopidas.

The Aetolian League, a federal state or “sympolity” of Aetolia, probably based on a looser tribal community, has been an ally of Thebes since 370, and in 367 is well-enough organized to conduct negotiations with Athens.

Aetolia's federal constitution provides for two main ruling bodies: a primary assembly, composed of all adult male citizens and presided over by the annually elected general (strategos), which meets at Thermum to elect officials and at various cities to transact other business; and a council (boule or synedrion), to supervise administration, in which cities are represented in proportion to their populations.

Apokletoi, a small group of at least thirty who are assigned essential duties in wartime, assist the strategos, who has complete control in the field.

Leadership within the league is always kept in Aetolian hands, since the more distant states, which are linked to the confederacy by isopolity (potential citizenship), have full civil, but no political, rights.

Dionysius II, Dionysius' son and successor as tyrant, halts the conflict in 367 on the same unfavorable terms established after his father's defeat in the third war with Carthage from 383 BCE to about 375 BCE.