Rise of Macedon

The exhaustion of the Greek heartland coincided with the rise of Macedon, led by Philip II. In twenty years, Philip had unified his kingdom, expanded it north and west at the expense of Illyrian tribes, and then conquered Thessaly and Thrace. His success stemmed from his innovative reforms to the Macedonian army. Phillip intervened repeatedly in the affairs of the southern city-states, culminating in his invasion of 338 BC.