Philip II Unifies Greece

While Athens and Sparta exhaust each other in decades of conflict, Philip II quietly builds Macedon into a military powerhouse. His innovations — the sarissa pike, the professional standing army, the combined-arms approach — make the Macedonian phalanx nearly unstoppable. At Chaeronea, his 18-year-old son Alexander commands the cavalry charge that breaks the Theban Sacred Band. Philip is assassinated two years later, but his unification of Greece sets the stage for Alexander's world-changing conquests.