Macedon had long been viewed by the southern Greeks as a barbaric frontier, culturally backward and politically unstable. But under Philip II (r. 359–336 BCE), it transformed into a disciplined, modernized kingdom and a military juggernaut.

Philip had been held hostage in Thebes during his youth, where he studied Greek politics and military tactics—especially the strategies of Epaminondas. When he returned to Macedon and ascended the throne, he inherited a weakened kingdom beset by external threats and internal chaos. In a few short years, he changed everything.

Philip’s Key Reforms:

The Macedonian Phalanx: Philip reorganized the traditional hoplite phalanx, arming his soldiers with the sarissa, a pike up to 18 feet long. This allowed for deeper, more flexible formations that could dominate older styles of Greek warfare.
Combined Arms: He integrated cavalry, skirmishers, and siege engines, creating a dynamic, professional army that could adapt to different terrains and enemies.
Diplomacy and Marriage: Philip skillfully used diplomacy and marriage alliances to neutralize enemies and expand influence.

Between 357 and 338 BCE, Philip steadily expanded Macedon’s borders. He conquered or subdued Thessaly, Thrace, and parts of Illyria. He intervened in the Sacred Wars in central Greece and gained legitimacy as protector of Apollo’s sanctuary at Delphi.

But it was clear he had set his sights on the fractious city-states of southern Greece.