A Macedonian army led by Philip II defeated the combined forces of Athens and Thebes in the Battle of Chaeronea, securing Macedonian hegemony in Greece and the Aegean.
The Battle of Chaeronea was fought in 338 BC, near the city of Chaeronea in Boeotia, between Macedonia under Philip II and an alliance of the Greek city-states led by Athens and Thebes. The battle was the culmination of Philip's final campaigns in 339338 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 concluding his ten-year conflict with Athens for supremacy in the north Aegean, by making a separate peace. Philip's much expanded kingdom, powerful army and plentiful resources now 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.
After several months of stalemate, Philip finally advanced into Boeotia in an attempt to march on Thebes and Athens. Opposing him, and blocking the road near Chaeronea, was the allied army, similar in size and occupying a strong position. Details of the ensuing battle are scarce, but after a long fight the Macedonians crushed both flanks of the allied line, which then dissolved into a rout.
The battle has been described as one of the most decisive of the ancient world. The forces of Athens and Thebes were destroyed, and continued resistance was impossible; the war therefore came to an abrupt end. Philip was able to impose a settlement upon southern Greece, which all states accepted, with the exception of Sparta. The League of Corinth, formed as a result, made all participants allies of Macedon and each other, with Philip as the guarantor of the peace. In turn, Philip was voted as strategos (general) for a pan-Hellenic war against the Achaemenid Empire, which he had long planned. However, before he was able to take charge of the campaign, Philip was assassinated, and the Kingdom of Macedon and responsibility for the war with Persia passed instead to his son Alexander.
The army of the Kingdom of Macedon was among the greatest military forces of the ancient world. It was created and made formidable by King Philip II of Macedon; previously the army of Macedon had been of little account in the politics of the Greek world, and Macedonia had been regarded as a second-rate power.
The latest innovations in weapons and tactics were adopted and refined by Philip II, and he created a uniquely flexible and effective army. By introducing military service as a full-time occupation, Philip was able to drill his men regularly, ensuring unity and cohesion in his ranks. In a remarkably short time, this led to the creation of one of the finest military machines of the ancient world. Tactical improvements included the latest developments in the deployment of the traditional Greek phalanx made by men such as Epaminondas of Thebes and Iphicrates of Athens. Philip II improved on these military innovators by using both Epaminondas' deeper phalanx and Iphicrates' combination of a longer spear and smaller and lighter shield. However, the Macedonian king also innovated; he introduced the use of a much longer spear, the two-handed pike. The Macedonian pike, the sarissa, gave its wielder many advantages both offensively and defensively. For the first time in Greek warfare, cavalry became a decisive arm in battle. The Macedonian army perfected the co-ordination of different troop types, an early example of combined arms tactics — the heavy infantry phalanx, skirmish infantry, archers, light cavalry and heavy cavalry, and siege engines were all deployed in battle; each troop type being used to its own particular advantage and creating a synergy of mutual support.
The new Macedonian army was an amalgamation of different forces. Macedonians and other Greeks (especially Thessalian cavalry) and a wide range of mercenaries from across the Aegean and Balkans were employed by Phillip. By 338 BC, more than a half of the army for his planned invasion of the Achaemenid Empire of Persia came from outside the borders of Macedon — from all over the Greek world and the nearby barbarian tribes, such as the Illyrians, Paeonians, and Thracians. After Philip's death, his successor, Alexander the Great, used the army to conquer the Achaemenid Empire.
Unfortunately, most of the primary historical sources for this period have been lost. As a consequence, scholarship is largely reliant on the works of Diodorus Siculus and Arrian, plus the incomplete writings of Curtius, all of whom lived centuries later than the events they describe.