Philomelus had asked the priestess to prophesy for him but she refused and, when threatened by force, stated that he may do as he wishes.

Taking this as a pronouncement, Philomelus has enlisted the support of Sparta and Athens.

Hence, only in 355 does Thebes formally inaugurate the Third Sacred War against Phocis, more or less gratuitously.

Phocis, however, has used the looted treasury to recruit and finance an efficient mercenary force of ten thousand men, and prepare for an invasion of Boeotia and Thessaly.

Demosthenes, a thirty-year-old professional speech writer (logographer), in 354 makes his first major speech before the Athenian Assembly, or Ecclesia (Ekklesia), a legislative body composed of all adult male citizens.

The speech, On the Navy Boards, addressed to the threat from the East, is a marked success.

The Assembly had convened to consider a rumored threat against Athens by the King of Persia.

Demosthenes' tightly reasoned oration helps persuade the Athenians to build up their naval strength quietly to show the Persians that, though Athens will not launch an attack, it is ready to fight.

He points out that, while Athens would have no allies if it attacked first, every other Greek city-state would join Athens if the Persians were the first to attack.

Revealing his penchant for careful fiscal planning, he proposes in the same speech an elaborate revision of the method used to tax the wealthy to raise money for ships.

The Third Sacred War continues in 354 BCE as the Theban and Locrian forces defeat those of Philomelus at Neon.

Philomelus, facing capture, jumps from a cliff to his death.

The Thebans, deeming all their prisoners sacrilegious, begin putting them to death, which causes the Phocians to kill Theban prisoners until the Thebans desist.

Epaminondas had sent Pammenes at the head of one thousand picked troops to defend Megalopolis when the city was founded, as it was apprehended that the Spartans would attack those engaged in that work.

A party among the Megalopolitans, who are for dissolving the community and returning to their own cantons, call upon the Mantineans and other Peloponnesians for aid in 352 BCE.

The Megalopolitans opposed to this dissolution of the state call in the aid of the Thebans, who send Pammenes with three thousand foot soldiers and three hundred cavalry to their assistance.

Pammenes with this force overcomes all resistance and compels the return of those who had left Megalopolis.

Philip meanwhile continues to gobble up territory, besieging and conquering Methone, an Athenian ally, in 355-354, losing an eye in the process.

Philip follows the conquest of Methone with some successes in Thrace, which Athens is unable to prevent despite halfhearted and tardy attempts to strengthen the independent Thracian princes through alliances with itself.

Even the great Athenian orator and statesman Demosthenes (384-322) is slow to realize that Athens' interest requires a united, not a divided, Thrace.

If Philip is to be stopped, it will not be by sea.

He can and arguably does time his operations to make it impossible for a fleet to get at him (ships cannot sail north when the Etesian winds are blowing).

On the positive side, the productivity of the silver and gold mines of the Pangaion region would be a huge asset to Philip, and thus it is encouraging that they are currently controlled by …

…the island of Thasos, a dwarf among imperial powers.

Although Thasos seems to have been extending its mainland interests remarkably in the 360s, it is not Athens and can be dealt with.

The Phocians, now led by Onomarchus, debate whether to make peace, but Onomarchus persuades is countrymen to melt down gold and silver ornaments to make coins to pay another army; and has bronze and iron beaten into new armor and weapons.

Onomarchus now forms an alliance with Lycrophon, the ruler of the Thessalian city of Pherae.

Thessaly as a whole had been willing enough to declare war on Phocis in keeping with an enmity of immemorial antiquity already remarked on as long-standing by Herodotus in the context of the Persian Wars.

Nonetheless, Thessalian unity is limited, as is Theban ability to influence events in Thessaly, and Onomarchus evidently succeeds in exploiting this fluid situation.

In a further complication, …

…another Thessalian city, Larissa, responds by issuing an invitation that is ultimately to be disastrous to Greek, as well as merely to Thessalian, freedom: it calls in Philip.

Onomarchus sends his brother Phayllus with seven thousand troops; but when they are beaten back by the Macedonians, Onomarchus leads twenty thousand men to victory over Philip's forces (his only defeat in the field), which then withdraw from Thessaly.

The victory for Onomarchus' Phocians over Philip, owing (it seems) to overconfidence and failure of reconnaissance, is unexpected; the Phocians seem to have had a “secret weapon,” in the form of nontorsion artillery.