The Peloponnesian War was fought in the Eastern Mediterranean between the Athenian-led Delian League and the Spartan-led Peloponnesian League from 431 to 404 BC for hegemony over Ancient Greece. Initially inconclusive, the intervention of the Persian Empire in support of Sparta in 413 BC allowed the Spartan coalition to decisively defeat Athens, beginning a period of Spartan hegemony over Greece.
The war consists of four related conflicts which have traditionally been combined into one. The opening phase, called the Ten Years' War or the Archidamian War, began in 431 BC when the Spartan king Archidamus II invaded Attica with his army. After successive Spartan invasions of Attica and Athenian raiding of the Peloponnese, Athens gained the upper hand at Sphacteria in 425 BC, but suffered a major defeat by Thebes at Delium in 424 BC. Both sides also faced rebellions within their respective alliances. With both city-states exhausted from years of fighting, the Peace of Nicias was signed in 421 BC. The second phase, the Argive War (419–416 BC), was a proxy war between Sparta and its Peloponnesian rivals, led by Argos and supported by Athens. The Argive alliance was defeated at Mantinea in 418 BC, restoring Spartan control over the Peloponnese. The third phase, the Sicilian Expedition, saw Athens attempt to conquer the Spartan-allied Syracuse. Fought between 415 and 413 BC, the expedition ended in defeat for Athens and the destruction of most of its navy.
After the expedition's failure, Sparta, now allied to the Persian Empire, broke the peace in 413 BC and began the final phase of the war, called the Decelean War or Ionian War. While Persia captured the Athenian cities in Asia Minor; Sparta, led by Lysander, built a Persian-financed fleet to break Athens's naval superiority. Sparta won the decisive battle of Aegospotami in 405 BC, which broke the power of the Delian League. Athens fell the following year and the Delian League was dissolved, ending the war. The Delian League's democracies were replaced with Spartan-style oligarchies, most notably the Thirty Tyrants in Athens. Spartan hegemony was short-lived after the victory. A decade later Athens regained its independence in the Corinthian War, and Sparta's power continued to fall in the years to come.
The war changed the ancient Greek world. Athens lost its Aegean empire and its maritime dominance, while Sparta became established as the leading power of Greece. The destruction of whole cities and large swathes of countryside made poverty widespread in the Peloponnese, while Athens was economically devastated and never regained its pre-war prosperity. The war also created subtler changes in Greek society. While Ancient Greek warfare had once been limited and formalised, with religious and cultural taboos preventing large-scale fighting, the conflict between the democratic Athenian alliance and the oligarchical Spartan alliance transformed it into total war between competing political ideologies, making civil war between those factions a common occurrence in the Greek world. The divisions and destruction caused by the war helped lead to foreign domination of the region and the end of the golden age of Greece.
Historic sources
The main historical source for most of the war is the detailed account in The History of the Peloponnesian War by Thucydides. He states that he began writing his history as soon as the war broke out and took his information from first-hand accounts, including events he witnessed himself. An Athenian who fought in the early part of the war, Thucydides was exiled in 423 BC and settled in the Peloponnese, where he spent the rest of the war collecting sources and writing his history. Scholars regard Thucydides as reliable and neutral between the two sides. A partial exception are the lengthy speeches he reports, which Thucydides admits are not accurate records of what was said, but his interpretation of the general arguments presented. The narrative begins several years before the war, explaining why it began, then reports events year-by-year. The main limitation of Thucydides' work is that it is incomplete: the text ends abruptly in 411 BC, seven years before the conclusion of the war.
The account was continued by Xenophon, a younger contemporary, in the first book of his Hellenica. This directly follows Thucydides' final sentence and provides a similar record, on the topics of the war's conclusion and aftermath. Born in Athens, Xenophon spent his military career as a mercenary, fighting in the Persian Empire and for Sparta in Asia Minor, Thrace and Greece. Exiled from Athens for these actions, he retired to live in Sparta, where he wrote Hellenica around 40 years after the war had ended. His account is generally considered favourable to Sparta.
A briefer account of the whole war is provided by the Sicilian historian Diodorus Siculus in books 12 and 13 of his Bibliotheca historica. Written in the first century BC, these books appear to be based heavily (possibly entirely) upon an earlier universal history by Ephorus, written in the century after the war, which is now lost.
The Roman-Greek historian Plutarch wrote biographies of four of the major commanders in the war (Pericles, Nicias, Alcibiades and Lysander) in his Parallel Lives. Plutarch's focus was on the character and morality of these men, but he does provide some details on the progress of the war that are not recorded elsewhere. Written in the first century AD, Plutarch based his work on earlier accounts which are now lost.
More limited information on the war is derived from epigraphy and archaeology, such as the walls of Amphipolis and grave of Brasidas, excavated in the 20th century. Some buildings and artworks produced during the war have survived, such as the Erechtheion temple and Grave Stele of Hegeso, both in Athens; these provide no information on military activity but do reflect civilian life during the war. Several plays by the Athenian Aristophanes were written and set during the war (particularly Peace and Lysistrata), but these are works of comedic fiction with little historical value.
Prelude
Thucydides summarised the situation before the war as: "The growth of the power of Athens, and the alarm which this inspired in Lacedaemon, made war inevitable". The nearly 50 years before the War had been marked by the development of Athens as a major power in the Mediterranean world. Its empire began as a small group of city-states, called the Delian League—from the island of Delos, on which they kept their treasury—that formed to ensure that the Greco-Persian Wars were over. After defeating the Second Persian invasion of Greece in the year 480 BC, Athens led the coalition of Greek city-states that continued the Greco-Persian Wars with attacks on Persian territories in the Aegean and Ionia. What ensued was a period which Thucydides called the Pentecontaetia, in which Athens increasingly became an empire, carrying out an aggressive war against Persia and increasingly dominating other city-states. Athens brought under its control all of Greece except for Sparta and its allies, ushering in a period now called the Athenian Empire. By mid-century, the Persians had been driven out of the Aegean and had ceded control of vast territories to Athens. Athens had greatly increased its own power; a number of its formerly independent allies were reduced, over the course of the century, to the status of tribute-paying subject states of the Delian League. This tribute was used to fund a powerful fleet and, after the middle of the century, massive public works in Athens, causing resentment.
Friction between Athens and the Peloponnesian states, including Sparta, began early in the Pentecontaetia. In the wake of the departure of the Persians from Greece, Sparta sent ambassadors to persuade Athens not to reconstruct their walls, but was rebuffed. Without the walls, Athens would have been defenceless against a land attack and subject to Spartan control. According to Thucydides, although the Spartans took no action then, 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 sizeable 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 did this 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 state, the Athenians settled them at the strategic city of Naupaktos on the Gulf of Corinth.
In 459 BC, there was a war between Spartan allies Megara and Corinth, which were neighbours of Athens. Athens took advantage of the war to make an alliance with Megara, giving Athens a critical foothold on the Isthmus of Corinth. A 15-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. But at its end, a massive Spartan invasion of Attica forced Athens to cede the lands it had won on the Greek mainland, and Athens and Sparta recognised 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.
Breakdown of peace
The Thirty Years' Peace was first tested in 440 BC, when Athens's powerful ally Samos rebelled from its alliance with Athens. The rebels quickly secured the support of a Persian satrap, and Athens faced the prospect of revolts throughout its empire. The Spartans, whose intervention would have been the trigger for a massive war to determine the fate of the empire, called a congress of their allies to discuss the possibility of war with Athens. Sparta's powerful ally Corinth was notably opposed to intervention, and the congress voted against war with Athens. The Athenians crushed the revolt, and peace was maintained.
The more immediate events that led to war involved Athens and Corinth. After a defeat by their colony of Corcyra, a sea power that was not allied to either Sparta or Athens, Corinth began to build an allied naval force. Alarmed, Corcyra sought alliance with Athens. Athens discussed with both Corcyra and Corinth, and made a defensive alliance with Corcyra. At the Battle of Sybota, a small contingent of Athenian ships played a critical role in preventing a Corinthian fleet from capturing Corcyra. In order to uphold the Thirty Years' Peace, the Athenians were instructed not to intervene in the battle unless it was clear that Corinth would invade Corcyra. However, the Athenian ships participated in the battle, and the arrival of additional Athenian triremes was enough to dissuade the Corinthians from exploiting their victory, thus sparing much of the routed Corcyrean and Athenian fleet.
Following this, Athens instructed Potidaea in the peninsula of Chalkidiki, a tributary ally of Athens but a colony of Corinth, to tear down its walls, send hostages to Athens, dismiss the Corinthian magistrates from office, and refuse the magistrates that Corinth would send in the future. Outraged, the Corinthians encouraged Potidaea to revolt and assured them that they would ally with them should they revolt from Athens. During the subsequent Battle of Potidaea, the Corinthians unofficially aided Potidaea by sneaking contingents of men into the besieged city to help defend it. This directly violated the Thirty Years' Peace, which stipulated that the Delian League and the Peloponnesian League would respect each other's autonomy and internal affairs.
A further provocation was Athens in 433/2 BC imposing trade sanctions on Megarian citizens (once more a Spartan ally after the First Peloponnesian War). It was alleged that the Megarians had desecrated the Hiera Orgas. These sanctions, known as the Megarian decree, were largely ignored by Thucydides, but some modern economic historians have noted that forbidding Megara to trade with the prosperous Athenian empire would have been disastrous for the Megarans, and so have considered the sanctions a contributing causing of the war. Historians who attribute responsibility for the war to Athens cite this event as the main cause.
At the request of Corinth, the Spartans summoned members of the Peloponnesian League to Sparta in 432 BC, especially those who had grievances with Athens, to make their complaints to the Spartan assembly. This debate was also attended by an uninvited delegation from Athens, which also asked to speak, and became the scene of a debate between the Athenians and the Corinthians. Thucydides reports that the Corinthians condemned Sparta's inactivity until then, warning Sparta that if it remained passive, it would soon be outflanked and without allies. In response, the Athenians reminded the Spartans of Athens's record of military success and opposition to Persia, warned them of confronting such a powerful state, and encouraged Sparta to seek arbitration as provided by the Thirty Years' Peace. The Spartan king Archidamus II spoke against the war, but the opinion of the hawkish ephor Sthenelaidas prevailed in the Spartan ecclesia. A majority of the Spartan assembly voted to declare that the Athenians had broken the peace, essentially declaring war.
Archidamian War (431–421 BC)
The first years of the war are known as the Archidamian War (431–421 BC), after Sparta's king Archidamus II. The first attack was by the Thebans on the Athenian outpost at Plataea, on 4 April 431 BC.
Sparta and its allies, except for Corinth, were almost exclusively land-based, and able to summon large armies which were 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 by 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 Archidamian War was to invade the land around Athens. While this invasion deprived Athenians of the productive land around their city, Athens maintained 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. At the end of the first year of the war, Pericles gave his famous Funeral Oration (431 BC).
The Spartans also occupied Attica for periods of only three weeks at a time; in the tradition of earlier hoplite warfare, the soldiers were 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. The longest Spartan invasion, in 430 BC, lasted just 40 days.