The Battle of Chaereonea was fought in 338 BC, near the city of Chaeronea in Boeotia, between Macedonia under Philip II and an alliance of city-states led by Athens and Thebes. The battle was the culmination of Philip's final campaigns in 339–338 BC and resulted in a decisive victory for the Macedonians and their allies.
Philip had brought peace to a war-torn Greece in 346 BC by ending the Third Sacred War and separately concluding his ten-year conflict with Athens for supremacy in the north Aegean with the Peace of Philocrates. Philip's much-expanded kingdom, powerful army and plentiful resources then made him the de facto leader of Greece. To many of the fiercely independent city-states, Philip's power after 346 BC was perceived as a threat, especially in Athens, where the politician Demosthenes led efforts to break away from Philip's influence. In 340 BC Demosthenes convinced the Athenian assembly to sanction action against Philip's territories and to ally with the Achaemenids in Byzantium, which Philip was besieging. These actions were against the terms of their treaty oaths and amounted to a declaration of war. In summer 339 BC, Philip therefore led his army towards South Greece, prompting the formation of an alliance of a few southern Greek states opposed to him, led by Athens and Thebes.