433 BC · Sybota Islands, off Epirus Theater

The naval battle of Sybota was one of the largest sea battles in Greek history before the Peloponnesian War formally began. Corinth — Sparta's key ally — clashed with Corcyra (modern Corfu) over control of the strategic colony of Epidamnus. Athens intervened on Corcyra's side, sending ten triremes as 'observers' with permission to fight only defensively. The Corinthian fleet initially won, but the timely arrival of Athenian reinforcements caused Corinth to withdraw. Both sides claimed victory. Athens's intervention brought it into direct conflict with Corinth and pushed Greece toward general war.

429–427 BC · Plataea, Boeotia Theater

Plataea — the city whose heroism at the 479 BC battle bore its name — was besieged by a Spartan and Boeotian army for two years. The Spartans built elaborate circumvallation walls around the city. Most of the garrison escaped through the Spartan lines on a dark winter night by a brilliant ruse, counting the courses of bricks in the siege wall and manufacturing ladders of precisely the right height. The remaining 200 Plataeans and 25 Athenians held out until starvation forced surrender. Their fate was brutal: tried before a Spartan court that asked only whether they had helped Sparta during the current war, all were executed.

425 BC · Pylos and Sphacteria, western Peloponnese Theater

Athenian general Demosthenes fortified a headland at Pylos on the Spartan coast, threatening Spartan control of Messenia. Sparta rushed forces to dislodge him and stationed 420 elite Spartiate hoplites on the adjacent island of Sphacteria to block the bay. Athenian ships broke through the naval cordon and blockaded Sphacteria, trapping the Spartans. After weeks of stalemate, the demagogue Cleon led a force of light-armed troops and Messenian guerrillas onto the island. Unable to come to grips with enemies who refused to stand and fight, the Spartans surrendered. 292 survivors walked into captivity — an unimaginable humiliation for the 'never surrender' culture of Sparta.

424 BC · Delium, Boeotia Theater

Flush with their successes at Pylos, Athens launched an ambitious two-pronged invasion of Boeotia. One column was supposed to distract the Boeotians while the other seized Delium; the plan unravelled and the Athenians faced the massed Boeotian army alone. Pagondas used an innovative tactic — concentrating his Theban contingent in a column 25 men deep while thinning his weaker allies — which overwhelmed the Athenian right. The Athenians routed; Hippocrates was killed among 1,000 Athenian hoplites. Socrates was among the survivors who fought their way out in good order.

422 BC · Amphipolis, northern Greece (Thrace) Theater

Both of the war's most aggressive leaders died at Amphipolis, opening the way to the Peace of Nicias. The Spartan general Brasidas had brilliantly seized Amphipolis, Athens's most important northern colony, by a surprise march the previous year. Cleon arrived to retake it. Brasidas launched a sudden sally from the city gates; Cleon, who had not expected a battle, was caught unprepared and killed while fleeing. The Athenians were routed, but Brasidas too received a mortal wound during the pursuit and died knowing his side had won. The city gave him a hero's burial.

418 BC · Mantinea plain, Arcadia (Peloponnese) Theater

The largest land battle of the Peloponnesian War pitted Sparta and its Peloponnesian allies against a coalition of Argos, Mantinea, and Athens. Agis II made tactical errors in his initial deployment but recovered brilliantly: he closed the gap before battle by an unexpected turn. The Spartan right routed its opponents, then wheeled to envelop the Argive-Athenian line that had briefly broken through on the other flank. The victory was crushing — over a thousand enemy dead — and restored Spartan prestige badly damaged by Sphacteria.

416–415 BC · Island of Melos, Cyclades Theater

Athens demanded that the neutral island of Melos — a Spartan colony that had tried to remain out of the war — join the Athenian Empire or be destroyed. The Melian dialogue, recorded by Thucydides, is one of the most chilling documents in history: Athenian envoys told the Melians bluntly that 'the strong do what they can and the weak suffer what they must.' The Melians refused. Athens besieged the island for months; starvation and betrayal forced surrender. The Athenians executed all men of military age and enslaved the women and children. The island was resettled with Athenian colonists.

415–413 BC · Sicily — Syracuse and surrounding territory Theater

Athens launched its greatest military gamble: an armada of 134 triremes and 27,000 men to conquer Syracuse and use Sicily as a base to encircle and strangle Sparta. The expedition went wrong from the start. Alcibiades — its visionary advocate — fled to Sparta after being recalled to face charges of sacrilege. Nicias, who had opposed the expedition, commanded it reluctantly and incompetently. The Spartan general Gylippus arrived and energised Syracusan resistance. Athens's navy was defeated in Syracuse harbour; a desperate overland retreat turned to slaughter. Almost the entire expedition was destroyed — perhaps 40,000 Athenian and allied soldiers and sailors killed or enslaved.

410 BC · Sea of Marmara (Propontis) Theater

After the catastrophe in Sicily, Athens rebuilt its fleet against all odds through desperate financial measures, including melting its gold victory statues. At Cyzicus, Alcibiades used a bold feint — luring the Spartan fleet out with a small squadron, then ambushing it with his full force emerging from fog — to destroy the entire Spartan fleet of 80 ships. Mindarus was killed in the fighting ashore. A captured Spartan dispatch conveyed the scale of the humiliation: 'The ships are gone. Mindarus is dead. The men are starving. We know not what to do.'

405 BC · Hellespont (Dardanelles straits) Theater

Lysander, the most brilliant Spartan naval commander, waited at the Hellespont with 170 Peloponnesian triremes. The Athenian fleet of 180 ships was beached opposite him at Aegospotami. For four days the Athenians rowed out to offer battle; Lysander refused, waiting. On the fifth day, when the Athenian crews scattered to forage for food, Lysander struck without warning. He captured almost the entire fleet on the beach. Of 180 ships, only 12 escaped with Conon. The 3,000–4,000 Athenian prisoners — all that remained of Athens's last fleet — were executed. Without a fleet, Athens could not be fed. The war was over.