Book I

Thucydides opens with his purpose and method, then traces Greek civilization from its earliest migrations through constant displacement, poverty, and piracy, arguing that ancient Greece was far weaker than its legend suggests.

Thucydides uses Homer to argue that Agamemnon's power rested on naval supremacy, and that the Trojan expedition, famous as it was, was actually quite modest compared to present-day forces.

Thucydides traces how Ionian power collided with Persia, how tyrants stunted Greek unity, and concludes that the true cause of the Peloponnesian War was Spartan fear of Athens' growing power.

Civil war at Epidamnus leads Corcyra to seek help from Corinth; rebuffed, they appeal to Athens. The Corcyraeans make their case that Athens needs their fleet, and should not let Corinth absorb them.

Corinth responds to Corcyra's appeal, accusing them of ingratitude. Athens, fearing war with Corinth but wanting Corcyra's fleet, makes a defensive alliance — triggering the confrontation at Sybota.

Corinth sails against Corcyra with a large fleet. The Athenians intervene just enough to stop a Corinthian victory; both sides claim victory and the confrontation hardens into open hostility.

Athens demands Potidaea pull down its walls and expel Corinthian magistrates; Potidaea revolts with Corinthian backing. Athens besieges the city, and Corinth covertly sends troops — setting off the final trigger for war.

Corinth summons the Peloponnesian allies to Sparta to denounce Athens. The Athenians are permitted to speak in their defense, arguing that their empire grew naturally from the Persian Wars and that Sparta has no grounds for complaint.

The Athenian envoys argue that their empire was built on merit and necessity, not aggression — that Sparta had the same opportunities and declined them, and that Athenian power serves as a check on Persia.

The wise Spartan king Archidamus warns against rushing to war without preparation, urging negotiation and patience. But Sthenelaidas calls for immediate war; the assembly votes overwhelmingly that Athens has broken the peace.

Thucydides traces the fifty-year rise of Athenian power after the Persian Wars, showing how Athens assumed naval leadership and gradually converted its alliance into an empire.

Cimon captures Eion, enslaves Scyros, and defeats the Persian fleet at the Eurymedon. Athens suppresses the Naxian revolt and defeats Thasos, steadily converting allies into subjects of the empire.

Athens crushes a Samian revolt after nine months, forcing surrender on humiliating terms. The Byzantines also submit. Athens is now unambiguously imperial, and Sparta watches with alarm.

A second congress at Sparta hears Corinthian accusations. The allies vote for war. Thucydides clarifies that the real cause was Spartan fear of Athens, not the formal grievances presented.

Thucydides recounts how Pausanias, the Spartan regent who defeated Persia at Plataea, secretly wrote to Xerxes offering to betray Greece, was recalled, and finally died of starvation after being walled up in a sanctuary to avoid sacrilege.

Thucydides follows Themistocles from his ostracism in Athens through his wandering exile, his correspondence with the Persian king, and his flight to Asia — where, unable to act against Greece, he reportedly drank bull's blood and died.

Sparta sends a series of ultimatums: expel the curse, relieve Potidaea, recognize Aegina's independence. Pericles advises Athens to refuse all concessions, confident they can endure a long war.

Pericles argues that Athens' financial reserves, naval superiority, and willingness to sacrifice land for sea-power give her every advantage; he urges the Athenians to fight, not negotiate.