The war began after sharp contests between Athens and Corinth over Corcyra (now Kérkira; 433) and Potidaea (432). The first important action was the initial invasion of Attica by a Spartan army in 431. Pericles brought the rural population within the walls, and the Athenian fleet began raids, winning victories off Naupactus (now Návpaktos). Meanwhile a plague (perhaps bubonic) wiped out (430-428) probably a quarter of the population of Athens, and Pericles died. His successor, Cleon, won a great victory at Sphacteria (now Sfaktiriá) and refused a Spartan bid for peace.
The Spartan leader Brasidas now brilliantly surprised Athens with a campaign in NE Greece, taking (424) Athenian cities, including Olynthus and Amphipolis. Fighting went on over these even after an armistice (423) and ended in a decisive Spartan victory at Amphipolis, in which Brasidas and Cleon were both killed (422). The new Athenian leader, Nicias, arranged a peace (421), but his rival Alcibiades persuaded the Athenians to invade powerful Syracuse. In the greatest expeditionary force a Greek city had ever assembled, Alcibiades and Nicias both had (415) commands, but before the attack on Syracuse had begun, Alcibiades was recalled to Athens to face a charge of sacrilege. He fled to Sparta; at his advice the Spartans set up a permanent base at Decelea in Attica and sent a military expert, Gylippus, to Syracuse. The incompetent Nicias lost his chance to surprise Syracuse, and after two years his force was wiped out (413).
Soon Persia was financing a Spartan fleet. Alcibiades sailed it across the Aegean, and there was (412) a general revolt of Athenian dependencies. At Athens the Four Hundred, an oligarchic council, managed (411) a short-lived coup, and Alcibiades, who had quit the Spartans, received (410) an Athenian command. He destroyed the Spartan fleet at Cyzicus (410). The new Spartan admiral, Lysander, built (407) a fleet with Persian aid and won a naval battle off Notium, and Alcibiades was driven from Athens. The Athenians won one more victory at Arginusae, near Lesbos, in 406 and again declined an offer of peace.
The next year Lysander wiped out the Athenian navy (at Aegospotamos, 405) and then besieged Athens, which capitulated in 404. Lysander installed an oligarchic government (the Thirty Tyrants) at Athens, which never regained its former importance. For about 30 years afterward Sparta was the main power in Greece.
The primary source for the Peloponnesian War (to 411) is Thucydides; Xenophon's Hellenica is an inferior sequel. See also G. E. M. de Ste. Croix, The Origins of the Peloponnesian War (1972); D. Kagan, The Peloponnesian War (2003): V. D. Hanson, A War like No Other (2005).
The Peloponnesian War reshaped the Ancient Greek world. On the level of international relations, Athens, the strongest city-state in Greece prior to the war's beginning, was reduced to a state of near-complete subjection, while Sparta was established as the leading power of Greece. The economic costs of the war were felt all across Greece; poverty became widespread in the Peloponnese, while Athens found itself completely devastated, and never regained its pre-war prosperity. The war also wrought subtler changes to Greek society; the conflict between democratic Athens and oligarchic Sparta, each of which supported friendly political factions within other states, made civil war a common occurrence in the Greek world.
Greek warfare, meanwhile, originally a limited and formalized form of conflict, transformed into an all-out struggle between city-states, complete with atrocities on a large scale. Shattering religious and cultural taboos, devastating vast swathes of countryside, and destroying whole cities, the Peloponnesian War marked the dramatic end to the fifth-century-B.C. golden age of Greece.
Friction between Athens and Peloponnesian states, including Sparta, began early in the Pentecontaetia; in the wake of the departure of the Persians from Greece, Sparta attempted to prevent the reconstruction of the walls of Athens (without the walls, Athens would have been defenseless against a land attack and subject to Spartan control), but was rebuffed. According to Thucydides, although the Spartans took no action at this time, they "secretly felt aggrieved.
Conflict between the states flared up again in 465 BC, when a helot revolt broke out in Sparta. The Spartans summoned forces from all of their allies, including Athens, to help them suppress the revolt. Athens sent out a sizable contingent (4,000 Hoplites), but upon its arrival, this force was dismissed by the Spartans, while those of all the other allies were permitted to remain. According to Thucydides, the Spartans acted in this way out of fear that the Athenians would switch sides and support the helots; the offended Athenians repudiated their alliance with Sparta. When the rebellious helots were finally forced to surrender and permitted to evacuate the country, the Athenians settled them at the strategic city of Naupactus on the Corinthian Gulf.
In 459 BC, Athens took advantage of a war between its neighbor Megara and Corinth, both Spartan allies, to conclude an alliance with Megara, giving the Athenians a critical foothold on the isthmus of Corinth. A fifteen year conflict, commonly known as the First Peloponnesian War, ensued, in which Athens fought intermittently against Sparta, Corinth, Aegina, and a number of other states. For a time during this conflict, Athens controlled not only Megara but also Boeotia; at its end, however, in the face of a massive Spartan invasion of Attica, the Athenians ceded the lands they had won on the Greek mainland, and Athens and Sparta recognized each other's right to control their respective alliance systems. The war was officially ended by the Thirty Years' Peace, signed in the winter of 446/5 BC.
The second test of the peace, and the immediate cause of the war, came in the form of several specific Athenian actions that affected Sparta's allies, notably Corinth. Athens was persuaded to intervene in a dispute between Corinth and Corcyra concerning the Civil War in Epidamnus, and, at the Battle of Sybota, a small contingent of Athenian ships played a critical role in preventing a Corinthian fleet from capturing Corcyra. It is worth noting, however, that the Athenians were instructed not to intervene in the battle. The presence of Athenian warships standing off from the engagement was enough to dissuade the Corinthians from exploiting their victory, thus sparing much of the routed Corcyraean fleet. Following this, Athens placed Potidaea, a tributary ally of Athens but an old colony of Corinth, under siege. The Corinthians, outraged by these actions, began to lobby Sparta to take action against Athens. Meanwhile, the Corinthians were unofficially aiding Potidaea by sneaking contingents of men into the besieged city to help defend it. This was a direct violation of the Thirty Years' Peace, which had (among other things) stipulated that the Delian League and the Peloponnesian League would respect each other's autonomy and internal affairs.
A further source of provocation was an Athenian decree, issued in 433/2 BC, imposing stringent trade sanctions on Megara (once more a Spartan ally after the conclusion of the First Peloponnesian War). These sanctions, known as the Megarian decree, were largely ignored by Thucydides, but modern economic historians have noted that forbidding Megara to trade with the prosperous Athenian empire would have been disastrous for the Megarans, and have accordingly considered the decree to be a contributing factor in bringing about the war.
In the context of these events, the Spartans called a conference of the Peloponnesian League at Sparta in 432 BC. This conference was attended by Athenian representatives as well as those from the members of the league, and became the scene of a debate between the Athenians and the Corinthians. Thucydides reports that the Corinthians condemned Sparta's inactivity up to that point, warning the Spartans that if they continued to remain passive while the Athenians were energetically active, they would soon find themselves outflanked and without allies. The Athenians, in response, reminded the Spartans of their record of military success and opposition to Persia, and warned them of the dangers of confronting such a powerful state. Undeterred, a majority of the Spartan assembly voted to declare that the Athenians had broken the peace, essentially declaring war.
Sparta and its allies, with the exception of Corinth, were almost exclusively land-based powers, able to summon large land armies which were very nearly unbeatable (thanks to the legendary Spartan forces). The Athenian Empire, although based in the peninsula of Attica, spread out across the islands of the Aegean Sea; Athens drew its immense wealth from tribute paid from these islands. Athens maintained its empire through naval power. Thus, the two powers were relatively unable to fight decisive battles.
The Spartan strategy during the first war, known as the Archidamian War after Sparta's king Archidamus II, was to invade the land surrounding Athens. While this invasion deprived Athens of the productive land around their city, Athens itself was able to maintain access to the sea, and did not suffer much. Many of the citizens of Attica abandoned their farms and moved inside the long walls, which connected Athens to its port of Piraeus. The Spartans also occupied Attica for periods of only three weeks at a time; in the tradition of earlier hoplite warfare the soldiers expected to go home to participate in the harvest. Moreover, Spartan slaves, known as helots, needed to be kept under control, and could not be left unsupervised for long periods of time. The longest Spartan invasion, in 430 BC, lasted just forty days.
The Athenian strategy was initially guided by the strategos, or general, Pericles, who advised the Athenians to avoid open battle with the far more numerous and better trained Spartan hoplites, relying instead on the fleet. The Athenian fleet, the most dominant in Greece, went on the offensive, winning victories at Naupactus (now known as "Návpaktos"). In 430, however, an outbreak of a plague hit Athens. The plague ravaged the densely packed city, and in the long run, was a significant cause of its final defeat. The plague wiped out over 30,000 citizens, sailors and soldiers and even Pericles and his sons. Roughly one third to two thirds of the Athenian population died. Athenian manpower was correspondingly drastically reduced and even foreign mercenaries refused to hire themselves out to a city riddled with plague. The fear of plague was so widespread that the Spartan invasion of Attica was abandoned, their troops being unwilling to risk contact with the diseased enemy.
After the death of Pericles, the Athenians turned somewhat against his conservative, defensive strategy and to the more aggressive strategy of bringing the war to Sparta and its allies. Rising to particular importance in Athenian democracy at this time was Cleon, a leader of the hawkish elements of the Athenian democracy. Led militarily by a clever new general Demosthenes (not to be confused with the later Athenian orator Demosthenes), the Athenians managed some successes as they continued their naval raids on the Peloponnese. Athens stretched their military activities into Boeotia and Aetolia, and began fortifying posts around the Peloponnese. One of these posts was near Pylos on a tiny island called Sphacteria, where the course of the first war turned in Athens's favour. The post off Pylos struck Sparta where it was weakest: its dependence on the helots. Sparta was dependent on a class of slaves, known as helots, to tend the fields while its citizens trained to become soldiers. The helots made the Spartan system possible, but now the post off Pylos began attracting helot runaways. In addition, the fear of a general revolt of helots emboldened by the nearby Athenian presence drove the Spartans to action. Demosthenes, however, outmanoeuvred the Spartans and trapped a group of Spartan soldiers on Sphacteria as he waited for them to surrender. Weeks later, though, Demosthenes proved unable to finish off the Spartans. After boasting that he could put an end to the affair in the Assembly, the inexperienced Cleon won a great victory at the Battle of Pylos and the related Battle of Sphacteria in 425 BC. The Athenians captured between 300 and 400 Spartan hoplites. The hostages gave the Athenians a bargaining chip.
After these battles, the Spartan general Brasidas raised an army of allies and helots and marched the length of Greece to the Athenian colony of Amphipolis in Thrace, which controlled several nearby silver mines; their product supplied much of the Athenian war fund. Thucydides was dispatched with a force which arrived too late to stop Brasidas capturing Amphipolis; Thucydides was exiled for this, and, as a result, had the conversations with both sides of the war which inspired him to record its history. Both Brasidas and Cleon were killed in Athenian efforts to retake Amphipolis (see Battle of Amphipolis). The Spartans and Athenians agreed to exchange the hostages for the towns captured by Brasidas, and signed a truce.
With the death of Cleon and Brasidas, zealous war hawks for both nations, the Peace of Nicias was able to last for some six years. However, it was a time of constant skirmishing in and around the Peloponnese. While the Spartans refrained from action themselves, some of their allies began to talk of revolt. They were supported in this by Argos, a powerful state within the Peloponnese that had remained independent of Lacedaemon. With the support of the Athenians, the Argives succeeded in forging a coalition of democratic states within the Peloponnese, including the powerful states of Mantinea and Elis. Early Spartan attempts to break up the coalition failed, and the leadership of the Spartan king Agis was called into question. Emboldened, the Argives and their allies, with the support of a small Athenian force under Alcibiades, moved to seize the city of Tegea, near Sparta.
The Battle of Mantinea was the largest land battle fought within Greece during the Peloponnesian War. The Lacedaemonians, with their neighbors the Tegeans, faced the combined armies of Argos, Athens, Mantinea, and Arcadia. In the battle, the allied coalition scored early successes, but failed to capitalize on them, which allowed the Spartan elite forces to defeat the forces opposite them. The result was a complete victory for the Spartans, which rescued their city from the brink of strategic defeat. The democratic alliance was broken up, and most of its members were reincorporated into the Peloponnesian League. With its victory at Mantinea, Sparta pulled itself back from the brink of utter defeat, and re-established its hegemony throughout the Peloponnese.
In the 17th year of the war, word came to Athens that one of their distant allies in Sicily was under attack from Syracuse. The people of Syracuse were ethnically Dorian (as were the Spartans), while the Athenians, and their ally in Sicilia, were Ionian. The Athenians felt obliged to assist their ally.
The Athenians did not act solely from altruism: rallied on by Alcibiades, the leader of the expedition, they held visions of conquering all of Sicily. Syracuse, the principal city of Sicily, was not much smaller than Athens, and conquering all of Sicily would have brought Athens an immense amount of resources. In the final stages of the preparations for departure, the hermai (religious statues) of Athens were mutilated by unknown persons, and Alcibiades was charged with religious crimes. Alcibiades demanded that he be put on trial at once, so that he might defend himself before the expedition. The Athenians however allowed Alcibiades to go on the expedition without being tried (many believed in order to better plot against him). After arriving in Sicily, Alcibiades was recalled back to Athens for trial. Fearing that he would be unjustly condemned, Alcibiades defected to Sparta and Nicias was placed in charge of the mission. After his defection, Alcibiades informed the Spartans that the Athenians planned to use Sicily as a springboard for the conquest of all of Italy, and to use the resources and soldiers from these new conquests to conquer all of the Peloponnese.
The Athenian force consisted of over 100 ships and some 5,000 infantry and light-armored troops. Cavalry was limited to about 30 horses, which proved to be no match for the large and highly trained Syracusan cavalry. Upon landing in Sicily, several cities immediately joined the Athenian cause. Instead of attacking at once, Nicias procrastinated and the campaigning season of 415 BC ended with Syracuse scarcely damaged. With winter approaching, the Athenians were then forced to withdraw into their quarters, and they spent the winter gathering allies and preparing to destroy Syracuse. The delay allowed the Syracusans to send for help from Sparta, who sent their general Gylippus to Sicily with reinforcements. Upon arriving, he raised up a force from several Sicilian cities, and went to the relief of Syracuse. He took command of the Syracusan troops, and in a series of battles defeated the Athenian forces, and prevented them from invading the city.
Nicias then sent word to Athens asking for reinforcements. Demosthenes was chosen and led another fleet to Sicily, joining his forces with those of Nicias. More battles ensued and again, the Syracusans and their allies defeated the Athenians. Demosthenes argued for a retreat to Athens, but Nicias at first refused. After additional setbacks, Nicias seemed to agree to a retreat until a bad omen, in the form of a lunar eclipse, delayed any withdrawal. The delay was costly and forced the Athenians into a major sea battle in the Great Harbor of Syracuse. The Athenians were thoroughly defeated. Nicias and Demosthenes marched their remaining forces inland in search of friendly allies. The Syracusan cavalry rode them down mercilessly, eventually killing or enslaving all who were left of the mighty Athenian fleet.
The Lacedaemonians were not content with simply sending aid to Sicily; they also resolved to take the war to the Athenians. On the advice of Alcibiades, they fortified Decelea, near Athens, and prevented the Athenians from making use of their land year round. The fortification of Decelea prevented the shipment of supplies overland to Athens, and forced all supplies to be brought in by sea at increased expense. Perhaps worst of all, the nearby silver mines were totally disrupted, with as many as 20,000 Athenian slaves freed by the Spartan hoplites at Decelea. With the treasury and emergency reserve fund of 1,000 talents dwindling away, the Athenians were forced to demand even more tribute from her subject allies, further increasing tensions and the threat of further rebellion within the Empire.
The Corinthians, the Spartans, and others in the Peloponnesian League sent more reinforcements to Syracuse, in the hopes of driving off the Athenians; but instead of withdrawing, the Athenians sent another hundred ships and another 5,000 troops to Sicily. Under Gylippus, the Syracusans and their allies were able to decisively defeat the Athenians on land; and Gylippus encouraged the Syracusans to build a navy, which was able to defeat the Athenian fleet when they attempted to withdraw. The Athenian army, attempting to withdraw overland to other, more friendly Sicilian cities, was divided and defeated; the entire Athenian fleet was destroyed, and virtually the entire Athenian army was sold off into slavery.
Following the defeat of the Athenians in Sicily, it was widely believed that the end of the Athenian Empire was at hand. Her treasury was nearly empty, her docks were depleted, and the flower of her youth was dead or imprisoned in a foreign land. They underestimated the strength of the Athenian Empire, but the beginning of the end was indeed at hand.
Following the destruction of the Sicilian Expedition, Lacedaemon encouraged the revolt of Athens's tributary allies, and indeed, much of Ionia rose in revolt against Athens. The Syracusans sent their fleet to the Peloponnesians, and the Persians decided to support the Spartans with money and ships. Revolt and faction threatened in Athens itself.
The Athenians managed to survive for several reasons. First, their foes were severely lacking in vigor. Corinth and Syracuse were slow to bring their fleets into the Aegean, and Sparta's other allies were also slow to furnish troops or ships. The Ionian states that rebelled expected protection, and many rejoined the Athenian side. The Persians were slow to furnish promised funds and ships, frustrating battle plans. Perhaps most importantly, Spartan officers were not trained to be diplomats, and were insensitive and politically inept.
At the start of the war, the Athenians had prudently put aside some money and 100 ships that were to be used only as a last resort.
These ships were now released, and served as the core of the Athenians' fleet throughout the rest of the war. An oligarchical revolution occurred in Athens, in which a group of 400 seized power. A peace with Sparta might have been possible, but the Athenian fleet, now based on the island of Samos, refused to accept the change. In 411 BC this fleet engaged the Spartans at the Battle of Syme. The fleet appointed Alcibiades their leader, and continued the war in Athens's name. Their opposition led to the reinstitution of a democratic government in Athens within two years.
Alcibiades, while condemned as a traitor, still carried weight in Athens. He prevented the Athenian fleet from attacking Athens; instead, he helped restore democracy by more subtle pressure. He also persuaded the Athenian fleet to attack the Spartans at the battle of Cyzicus in 410. In the battle, the Athenians obliterated the Spartan fleet, and succeeded in re-establishing the financial basis of the Athenian Empire.
Between 410 and 406, Athens won a continuous string of victories, and eventually recovered large portions of its empire. All of this was due, in no small part, to Alcibiades.
Faction triumphed in Athens: following a minor Spartan victory by their skillful general Lysander at the naval battle of Notium in 406 BC. Alcibiades was not re-elected general by the Athenians and he exiled himself from the city. He would never again lead Athenians in battle. Athens was then victorious at the naval battle of Arginusae. The Spartan fleet under Callicratidas lost 70 ships and the Athenians lost 25 ships. But, due to bad weather, the Athenians were unable to rescue their stranded crews or to finish off the Spartan fleet. Despite their victory, these failures caused outrage in Athens and led to a controversial trial. The trial resulted in the execution of six of Athens’s top naval commanders. Athens’s naval supremacy would now be challenged without several of its most able military leaders and a demoralized navy.
Unlike some of his predecessors the new Spartan general, Lysander, was not a member of the Spartan royal families and was also formidable in naval strategy; he was an artful diplomat, who had even cultivated good personal relationships with the Persian prince Cyrus, the son of Darius II. Seizing its opportunity, the Spartan fleet sailed at once to the Hellespont, the source of Athens' grain. Threatened with starvation, the Athenian fleet had no choice but to follow. Through cunning strategy, Lysander totally defeated the Athenian fleet, in 405 BC, at the battle of Aegospotami, destroying 168 ships and capturing some three or four thousand Athenian sailors. Only 12 Athenian ships escaped, and several of these sailed to Cyprus, carrying the "strategos" (General) Conon, who was anxious not to face the judgment of the Assembly.
Facing starvation and disease from the prolonged siege, Athens surrendered in 404 BC, and her allies soon surrendered as well. The democrats at Samos, loyal to the bitter last, held on slightly longer, and were allowed to flee with their lives. The surrender stripped Athens of her walls, her fleet, and all of her overseas possessions. Corinth and Thebes demanded that Athens should be destroyed and all its citizens should be enslaved. However the Spartans announced their refusal to destroy a city that had done a good service at a time of greatest danger to Greece, and took Athens into their own system. Athens was "to have the same friends and enemies as Sparta.
By doing so the victorious Spartans proved to be the most clement state that fought Athens and at the same time they turned out to be her saviour, as neither Corinth nor Thebes at the time could challenge their decision.
For a short period of time, Athens was ruled by the 'Thirty Tyrants' and democracy was suspended. This was a reactionary regime set up by Sparta. The oligarchs were overthrown and democracy was restored by Thrasybulus in 403 BC. Although the power of Athens was broken, it made something of a recovery as a result of the Corinthian War and continued to play an active role in Greek politics. Sparta was in turn humbled by Thebes at the Battle of Leuctra in 371 BC, but it was all brought to an end a few years later when Philip II of Macedon conquered all of Greece.
The war continues to fascinate later generations, both because of the way it engulfed the Greek world, and because the democracy of Athens lost to the far more militant Sparta. Also, the insight Thucydides provides into the motivations of its participants is deeper than what is known about any other war in ancient times.