Philip II Unites Greece Under Macedon

The event

King Philip II transformed Macedon from a peripheral kingdom into the dominant military power of the Greek world. He reorganized his infantry around the deadly Macedonian phalanx, armed with the long sarissa spear, and built a professional army unlike anything Greece had seen. Exploiting the exhaustion left by the Peloponnesian War, Philip defeated the combined forces of Athens, Thebes, and their allies at the Battle of Chaeronea in 338 BC and organized the Greek city-states, somewhat unwillingly, into the League of Corinth under his leadership.

With Greece finally unified, Philip began planning a great invasion of the Persian Empire, framed as revenge for Xerxes' invasion generations earlier. He never lived to carry it out — Philip was assassinated in 336 BC, and the throne, the army, and the Persian campaign all passed to his twenty-year-old son, Alexander.