Outbreak of the Peloponnesian War
Thucydides identified the war's underlying cause with precision: 'The growth of Athenian power and the fear this inspired in Sparta made war inevitable.' The immediate triggers were disputes over Corcyra and Potidaea — Corinthian allies whose conflicts drew Athens in — and Sparta's ultimatum that Athens lift the Megarian Decree, an economic embargo. Pericles' strategy was defensive-offensive: Athens would avoid land battles with Sparta's superior army, use its fleet to raid the Peloponnesian coast, maintain the empire's tribute income, and wait for Sparta to exhaust itself. Sparta's strategy was to annually invade Attica, destroying crops and forcing Athens to fight — the strategy of Archidamus, hence the war's first phase is called the Archidamian War. The Spartans annually ravaged Attica while Athenians watched from behind their walls, connected to the sea by the Long Walls to Piraeus. The Athenians retaliated with naval raids. Neither side could deliver a knockout blow. The war settled into attrition. Thucydides wrote his History with cold analytical detachment, depicting power politics without divine intervention, seeking universal lessons in human nature. His famous Melian Dialogue — where Athenians tell the Melians 'the strong do what they can and the weak suffer what they must' — remains one of antiquity's most cited texts on international relations. The war lasted twenty-seven years through several phases, devastating the Greek world. Population losses from warfare, plague, and famine were enormous. Many historians see it as the event that fatally weakened classical Greek civilization and opened the door to Macedonian conquest.
- Year: 431 BCE
- Category: Military
