Peloponnesian War
The 27-year war between Athens and Sparta, turned by Thucydides into realism's founding text and the archetype of a rising power alarming an established rival.
For twenty-seven years the two strongest powers in the Greek world ground each other down, and when it was over the winner had mortgaged Greek freedom to Persia to pay for victory. The Peloponnesian War, fought from 431 to 404 BC, pitted Athens against Sparta and dragged nearly every other city into the wreckage. It is remembered less for who won than for the man who wrote it down, and for a single brutal conversation about power that students still read today.
Two kinds of power
The war was a collision between opposites. Athens was a maritime democracy, its wealth drawn from the tribute of the Delian League, its safety resting on the finest navy in Greece and the Long Walls that tied the city to its port. Sparta was a land power, an austere oligarchy whose hoplite infantry no one wished to meet in open battle. Pericles, Athens's leading citizen, built his strategy around the mismatch: pull the population inside the walls, refuse the land battle Sparta wanted, and let the fleet bleed the enemy coast. Then in 430 BC a plague tore through the overcrowded city and killed perhaps a quarter of its people, Pericles among them in 429. Athens had held off Sparta's army only to lose to its own crowded streets.
The long unraveling
The first decade, the Archidamian War, ended in the exhausted, temporary Peace of Nicias in 421 BC. Then Athens made the gamble that doomed it. In 415 BC it launched an enormous expedition to conquer Syracuse in far-off Sicily, a war of choice against a city that had done it little harm. The command unraveled at once: Alcibiades, its most brilliant general, was recalled to face trial and instead defected to Sparta, advising the enemy how to break his own city. By 413 BC the entire expedition, fleet and army together, had been destroyed. The final blow came at sea. Financed by Persian gold, the Spartan admiral Lysander caught the Athenian fleet beached at Aegospotami in 405 BC and annihilated it. Cut off from the grain it imported by sea, Athens surrendered in 404, tore down its Long Walls, and briefly submitted to the Spartan-installed junta remembered as the Thirty Tyrants.
Thucydides and the Melian Dialogue
The war produced the first work of what we would now call realist history. Thucydides, an Athenian general exiled after a defeat, wrote its account not as a tale of gods and glory but as a cold study of power, fear, and interest, meant to be a possession "forever." His most infamous scene is the Melian Dialogue of 416 BC, in which Athenian envoys tell the small neutral island of Melos that there is no point appealing to justice between unequals: "the strong do what they can and the weak suffer what they must." Melos refused to submit. Athens killed its men and enslaved its women and children. That is why the war became the permanent archetype of a rising power frightening an established one, exactly as Thucydides diagnosed the cause: it was the growth of Athenian power, and the fear it stirred in Sparta, that made the war inevitable.