The Peloponnesian War: Athens, Sparta and the Cost of Power

The night Athens learned it might lose everything

The news reached Athens after dark.

A warship called the Paralus had arrived at the harbour of Piraeus, bringing word of a catastrophe.

The Athenian fleet had been caught by surprise near Aegospotami, on the Hellespont. Most of its ships were captured by the Spartans before their crews could put to sea.

For a city whose strength depended on the sea, the news was devastating. The Hellespont was no ordinary stretch of water. It connected the Aegean with the routes towards the Black Sea, through which grain and other supplies could reach Athens.

Without a fleet capable of protecting those routes, the city faced something far worse than another military defeat.

It faced starvation.

The historian Xenophon describes how the news spread through the harbour and along the Long Walls connecting Piraeus to Athens. One person passed it to another, until the sound of mourning travelled towards the city itself.

The Athenians grieved for those they had lost, but Xenophon tells us they were also afraid of what might happen to them.

For years, Athens had been the dominant power in an empire stretching across much of the Aegean. It had forced rebellious allies back into submission, punished defeated communities and made decisions that had destroyed the lives of other Greeks.

Now Athens was the defeated city.

Its enemies would decide what happened next.

The disaster at Aegospotami came in 405 BCE. By the following year, Athens could no longer resist. The war had lasted twenty-seven years.

Hunger had taken its toll. Spartan forces threatened the city by land and sea. Athens had lost the naval power that had once made it extraordinarily difficult to defeat.

The terms of surrender were humiliating. Athens would give up almost all its remaining warships, abandon its independent alliances and tear down the fortifications that had protected it for generations.

Xenophon describes the destruction of the walls taking place to the sound of flutes, as the victorious Peloponnesians celebrated what they regarded as the liberation of Greece.

It was a remarkable reversal. The walls that had once symbolised Athenian security were being dismantled, and the empire that had made Athens rich and powerful was gone. The Greeks who had spent decades fighting one another were left to deal with what the war had done to their world.

How had it come to this?

To understand why Athens and Sparta went to war, we need to go back to a time when they had been allies.

Before the war, Athens and Sparta had fought together

In the early fifth century BCE, the Greek city-states faced a common enemy.

The Persian Empire had expanded into the Aegean world, bringing Greek communities in Asia Minor under its authority and launching campaigns against mainland Greece. Athens and Sparta played important roles in resisting the Persian invasions.

At Marathon in 490 BCE, the Athenians defeated a Persian expedition. Ten years later, Greek forces fought against the invasion led by Xerxes.

Sparta became famous for the defence of Thermopylae, while Athens contributed heavily to the Greek fleet that defeated Persian forces at Salamis.

The victories of 480 and 479 BCE became defining moments in Greek history. But defeating Persia did not create a united Greek state.

The Greek world consisted of numerous independent communities, each with its own interests, traditions, political arrangements and rivalries. Athens and Sparta were two of the most powerful, but they were also very different.

Sparta was a land-based military power in the southern Greek peninsula known as the Peloponnese. Its political system combined several institutions, including two kings and a council of elders, with power concentrated in a relatively small citizen population.

Spartan society depended heavily on the labour of the helots, an unfree population who worked the land and supported the Spartan way of life.

Athens, by contrast, developed a democracy in which male citizens could participate directly in political decision-making. That democracy excluded women, enslaved people and resident foreigners, but it still gave a substantial body of citizens a political voice.

Athens also possessed something Sparta did not: an increasingly powerful maritime empire.

Following the Persian Wars, Athens led an alliance commonly called the Delian League. Its members contributed ships or money towards continuing the struggle against Persia and protecting Greek interests in the Aegean.

Over time, however, the relationship changed. Athens increasingly controlled the alliance's decisions and finances. Communities that attempted to leave could be forced back into submission.

The alliance had become an empire.

Athens could still present itself as the protector of its allies, but many of those allies had little practical freedom to disagree with it.

Sparta led its own alliance, usually called the Peloponnesian League, although its relationships with allied states differed from Athens' imperial arrangements.

For decades, these two powerful networks existed alongside one another, sometimes uneasily. As Athenian influence expanded, the possibility of conflict grew.

But war was not inevitable simply because the two powers were different. There were particular disputes, decisions and political pressures that gradually brought them into confrontation.

Why did they go to war?

The historian Thucydides believed that the growth of Athenian power, and the fear it created in Sparta, was the deepest cause of the conflict.

It's a famous interpretation, and an important one. But it doesn't mean the war began because Athens and Sparta simply disliked one another.

The immediate disputes involved other Greek communities.

Corinth, an important Spartan ally, became increasingly alarmed by Athenian involvement in disputes affecting its interests.

The conflict surrounding Corcyra, an island with a significant fleet, brought Athens into confrontation with Corinth.

Potidaea, another community with connections to Corinth, became a further source of tension. Athens also imposed restrictions on Megara, a member of Sparta's alliance, contributing to the growing hostility.

These disputes mattered because they involved alliances, obligations and competing ideas about security. A decision that seemed defensive to Athens might look threatening to Sparta or Corinth, and smaller states had their own reasons for demanding support from the larger powers.

By 432 BCE, Sparta and its allies were debating whether Athens had broken existing agreements. The Spartans eventually decided that the peace had been violated.

War followed in 431 BCE.

If you're looking for a first substantial history of the conflict, Donald Kagan's The Peloponnesian War is an excellent place to begin.

Kagan follows the war from its origins to Athens' defeat, explaining the political decisions, military campaigns and personalities that shaped its course. He gives readers a coherent narrative through a complicated twenty-seven-year conflict.

That makes his book particularly useful when you're first trying to understand how the different events fit together.

The Peloponnesian War wasn't a single continuous campaign. It changed character several times, and there were periods when Athens and Sparta were formally at peace.

Understanding those changes makes the history much easier to follow.

Two powers with very different ways of fighting

At the beginning of the war, Athens and Sparta faced a difficult problem. Neither could easily defeat the other in the kind of fighting at which its opponent was strongest.

Sparta possessed formidable land forces. Its citizen soldiers, supported by allied contingents, were experienced in the kind of close-order infantry warfare that dominated Greek battlefields.

Athens had an effective army of its own, but its greatest advantage lay at sea.

Its warships, called triremes, were long, narrow vessels propelled by three levels of rowers. They could move quickly, manoeuvre in battle and support operations across the Aegean.

Athens also possessed powerful defensive walls. The Long Walls connected the city to Piraeus, allowing Athens to maintain access to its harbour even when hostile armies threatened the surrounding countryside.

That was the foundation of the strategy associated with the Athenian statesman Pericles.

Rather than risk a decisive land battle against Sparta, the Athenians would rely on their fortifications and naval strength.

Spartan armies might invade and devastate the countryside of Attica, the territory surrounding Athens, but they could not easily force the city itself to surrender. Athens could receive supplies by sea and launch attacks against enemy territory.

The strategy had a certain logic.

Why fight your enemy where he is strongest?

The difficulty was what this meant for the people living outside the city.

Farmers faced the destruction of crops, homes and property. Families were forced to abandon their land and take shelter behind Athens' walls.

It also meant concentrating large numbers of people inside the city. The consequences would soon be terrible.

For readers particularly interested in how the war was fought, J. F. Lazenby's The Peloponnesian War is a valuable companion to Kagan.

Lazenby concentrates more closely on campaigns, strategy and military decisions. He examines what the opposing sides were trying to achieve, how their plans developed and why particular victories or defeats mattered.

You don't need that level of military detail to begin understanding the war, but it becomes particularly rewarding once you know the broad sequence of events.

Athens could keep Sparta outside its walls. It could not keep everything out.

In 430 BCE, disease spread through Athens.

The population had been swollen by people seeking refuge from the Spartan invasions. Conditions were crowded, and the city was already living under the pressures of war. The outbreak was devastating.

Thucydides, who survived the disease himself, left a detailed description of its symptoms and effects.

People died in enormous numbers. Families suffered, ordinary customs surrounding illness and burial were disrupted, and fear and desperation changed the way some people behaved towards one another.

Thucydides describes a city struggling not only with disease but with the breakdown of familiar social expectations.

The precise identity of the disease remains debated, but its impact is not.

In 429 BCE, Pericles died. Athens had lost one of its most influential political leaders at a moment when the war was already placing enormous strain on the city.

Yet the Athenians continued fighting. Their naval power remained formidable, and the Spartans still had no straightforward way to overcome Athens' defences. The war that might have seemed manageable when it began was becoming something much harder to control.

Thucydides doesn't present the war as an uninterrupted sequence of armies marching and generals making speeches.

He also shows us disease, fear, political disagreement and the ways ordinary human behaviour could change under pressure.

And his account becomes more disturbing as the conflict spreads beyond Athens and Sparta.

The war belonged to far more than two cities

It's tempting to think of the Peloponnesian War as Athens against Sparta, with everyone else playing a supporting role. The reality was much more complicated.

Greek communities throughout the Aegean, the mainland and eventually Sicily became involved. Some were powerful states pursuing their own ambitions. Others were smaller communities trying to survive between larger rivals.

Take Plataea.

This small Boeotian city had longstanding connections with Athens and had fought alongside the Athenians against Persia.

When war broke out in 431 BCE, Theban forces attempted to seize it. The conflict over Plataea eventually became a prolonged siege involving Sparta and its allies.

After the city's surrender in 427 BCE, many of its surviving male defenders were executed, and the community was destroyed.

Plataea's fate makes it difficult to describe the war simply as a rivalry between two great powers. For the people caught between them, defeat could mean the destruction of their entire political community.

Something similar appears in Thucydides' account of Mytilene, a city on the island of Lesbos.

When Mytilene revolted against Athenian control, Athens responded with force. After suppressing the rebellion in 427 BCE, the Athenian assembly initially voted for an extraordinarily severe punishment.

The decision was reconsidered the following day, and the order for a general massacre was reversed. But Athens still executed men it held responsible for the revolt and imposed other severe penalties.

The episode reveals just how far Athens was prepared to consider going in defence of its empire.

These were decisions made by a democratic citizen assembly. That doesn't mean Athenian democracy was meaningless. It means we should resist imagining democratic Athens as automatically generous or humane towards the communities it ruled.

Thucydides also describes civil conflict on Corcyra, where rival political factions became entangled in the wider war.

Violence escalated, former neighbours turned against one another and political loyalties became matters of life and death.

Athens and Sparta didn't simply fight battles against each other. Their rivalry could deepen existing tensions within other communities, making local disputes more violent and harder to resolve.

A conflict that began between powerful alliances was changing the political and social life of the Greek world.

Thucydides: the man who tried to understand the war

If there's one ancient writer at the centre of this subject, it's Thucydides.

He lived through the Peloponnesian War and served as an Athenian general.

In 424 BCE, he was unable to prevent the strategically important city of Amphipolis from falling to the Spartan commander Brasidas, although he did secure the nearby port of Eion against him. Thucydides was subsequently exiled.

That experience gave him an unusual relationship with the war. He was an Athenian who had participated in the conflict, but his exile also gave him opportunities to investigate events beyond Athens.

His surviving history is one of the most remarkable works of ancient historical writing.

For an English edition, I would recommend the Oxford World's Classics translation of The Peloponnesian War by Martin Hammond, with an introduction and notes by P. J. Rhodes.

It's a strong choice for serious readers who want a readable translation supported by substantial historical guidance.

Thucydides begins by examining the growth of Greek power and the circumstances leading to war. He then follows the conflict through its early years, the uneasy peace, the Sicilian expedition and the beginning of its final phase.

But he isn't merely recording events.

He repeatedly examines why people make decisions, how political leaders persuade others and what happens when fear, ambition or anger influence judgement.

One of the most interesting aspects of his history is the speeches.

Thucydides presents political leaders, generals and ambassadors addressing assemblies or debating what should happen next.

Some of these speeches are extraordinary pieces of writing, but they aren't court transcripts or recordings of exactly what was said.

Thucydides explains that he reconstructed speeches according to what he considered appropriate to the circumstances, while trying to preserve the general meaning of the arguments.

The speeches help us understand how Thucydides interpreted the political decisions of the war, but we have to be careful about treating every speech as a precise record of an individual's words.

George Cawkwell's Thucydides and the Peloponnesian War is particularly useful once you want to investigate questions like these more deeply.

Cawkwell challenges aspects of Thucydides' interpretation, examining his treatment of important figures, his explanations of strategy and his understanding of Athenian power.

It's a more demanding book than Kagan's narrative history, but it helps answer an important question: when we read Thucydides, how much are we learning about the war itself, and how much are we seeing the war through Thucydides' interpretation?

There's no reason to dismiss him as unreliable. He's simply too important a writer to read without asking questions of his account.

Sparta suffered a defeat few expected

By the middle years of the war, neither Athens nor Sparta had achieved the decisive victory it wanted. Both sides had experienced successes and reverses.

But one episode in 425 BCE was particularly surprising.

Athenian forces established a position at Pylos, on the western coast of the Peloponnese. Fighting developed around the nearby island of Sphacteria, where a group of Spartan soldiers became isolated.

The Athenians eventually forced the surviving Spartans to surrender.

That was deeply significant. Spartans were famous for their military discipline and willingness to die rather than abandon their position.

Here, Spartan soldiers had surrendered.

The Athenians captured valuable prisoners and gained an important advantage in negotiations. But the war continued.

The Spartan commander Brasidas achieved successes in northern Greece, challenging Athenian control over strategically important communities. His capture of Amphipolis in 424 BCE was particularly damaging to Athenian interests.

In 422 BCE, both Brasidas and the Athenian politician and general Cleon were killed during fighting at Amphipolis.

Their deaths removed two influential figures associated with continuing the conflict. The following year, Athens and Sparta agreed to peace.

After ten years of warfare, it seemed possible that the worst was over.

It wasn't.

The peace that didn't bring peace

The agreement of 421 BCE is known as the Peace of Nicias, after the Athenian statesman associated with its negotiation.

It was intended to establish a lasting settlement between Athens and Sparta, but many problems remained.

Not every ally supported the agreement. Territorial disputes continued, promised arrangements were not always carried out, and the wider Greek world remained divided.

The war had created tensions that a treaty between Athens and Sparta could not simply remove. New alliances formed, and old rivalries continued.

In 418 BCE, Sparta won an important victory at Mantinea, restoring some of its military prestige.

Meanwhile, Athens was still concerned with preserving its power and authority over the Aegean.

One of the most troubling episodes of this period occurred on the island of Melos.

The Melians had resisted incorporation into the Athenian Empire. In 416 BCE, Athens attacked the island.

Thucydides presents a remarkable dialogue between Athenian representatives and Melian leaders, in which the opposing sides discuss power, security, justice and the consequences of resistance.

The Athenians argue from the position of a much stronger state.

The Melians hope that justice, their own determination and possible Spartan assistance will help preserve their independence.

The discussion has become famous because of what it reveals about the relationship between power and morality.

But we should remember that Thucydides constructed the dialogue as part of his history. We cannot assume the conversation occurred exactly as he presents it.

What happened to Melos, however, is not simply a philosophical problem.

After the island surrendered, the Athenians executed the adult male prisoners and enslaved the women and children.

This happened during the period traditionally called the Peace of Nicias.

The episode is a grim reminder that peace between major powers did not necessarily mean safety for everyone else.

And while Athens was defending its existing empire, some of its leaders were looking towards opportunities much farther west.

Sicily: the expedition that changed everything

In 415 BCE, Athens launched one of the most ambitious military expeditions in its history.

Its destination was Sicily.

The island was home to numerous Greek cities, among them Syracuse, one of the most powerful communities in the western Greek world.

Athens had interests and allies in the region. An appeal from Segesta, which was involved in a conflict with Selinus, helped bring the question of intervention before the Athenian assembly.

But the proposed expedition raised much larger questions.

How far should Athens extend its influence? Could it afford another major campaign while its position in Greece remained insecure?

And what exactly would success look like?

Two leading figures in the debate were Nicias and Alcibiades.

Nicias was cautious about the expedition. Alcibiades was ambitious, charismatic and eager to pursue opportunities for Athenian power and influence.

Athens eventually voted to send an enormous force.

The scale of the expedition was impressive. Ships, soldiers, supplies and commanders were assembled for a campaign far from Athens, but size did not guarantee success.

Soon after the expedition began, Alcibiades was recalled to face accusations relating to religious scandals at Athens.

Rather than return for trial, he fled and eventually joined Sparta.

One of the men most strongly associated with advocating the expedition was now assisting Athens' enemies.

Meanwhile, the campaign in Sicily became increasingly difficult.

The Athenians attempted to bring Syracuse under pressure, but the city resisted. Syracuse received support from Sparta and other Greek communities.

The fighting involved land operations, siege warfare and naval battles in the confined waters around the city.

Athenian expectations of a successful intervention gradually gave way to a desperate struggle.

Reinforcements arrived from Athens, but they could not reverse the situation.

By 413 BCE, the expedition had become a catastrophe.

The Athenians attempted to escape. Their fleet suffered defeat, and the retreating land forces were pursued and overwhelmed.

Nicias and his fellow commander Demosthenes were captured and executed. Thousands of Athenian and allied soldiers were killed or taken prisoner.

For Athens, it was an extraordinary loss of men, ships and resources. And the political consequences were enormous.

The city had committed so much to the expedition that rebuilding its strength would be difficult. Its allies could see that Athenian power was vulnerable, and its enemies could see an opportunity.

Thucydides' account of the Sicilian expedition, contained in Books Six and Seven of his history, is among the most compelling sections of ancient historical writing.

It's particularly worth reading after you understand the broad narrative of the war.

Knowing that the expedition ends in disaster doesn't make the account less interesting. It makes the choices along the way more difficult to ignore.

At several points, the Athenians still have decisions to make.

They could reconsider their objectives, change their plans or withdraw. Instead, the expedition moves towards a catastrophe that becomes harder and harder to escape.

The important question isn't simply why Athens lost in Sicily. It's how a powerful state came to commit itself so deeply to a campaign that ultimately threatened its own survival.

Athens was weakened, but the war wasn't over

The disaster in Sicily did not immediately end the Peloponnesian War. Athens still possessed resources, experienced commanders and the ability to rebuild naval forces.

But the strategic situation had changed.

Sparta began to apply pressure more continuously. In 413 BCE, Spartan forces occupied and fortified Decelea, a position in Attica that allowed them to threaten Athens and its surrounding territory.

Unlike the earlier invasions, this created a more permanent enemy presence close to the city.

At the same time, the war increasingly shifted towards the Aegean and the eastern Greek world.

Some communities under Athenian control revolted. Sparta developed its naval strength, and the Persian Empire became an increasingly important participant in the struggle.

Persian officials and resources helped support Spartan naval operations. That was particularly significant because Athens' greatest advantage had always been its fleet.

Sparta had begun the war as the stronger land power. Now it was becoming capable of challenging Athens at sea.

The Athenians were also divided among themselves.

In 411 BCE, a group wanting to replace democracy with rule by a small elite seized power in Athens and established a government known as the Four Hundred.

The new regime was short-lived, but the episode revealed how severely the war had affected Athenian politics.

Athens was fighting its enemies while arguing over how it should govern itself.

Yet its resistance continued.

The Athenians won important naval victories, including at Cyzicus in 410 BCE. Even after the Sicilian disaster, they remained capable of defeating Spartan forces. The final outcome was still uncertain.

The last years Thucydides never finished

There's a complication when we try to follow the final stage of the war through ancient sources.

Thucydides' surviving history ends in 411 BCE.

It stops before the final Athenian victories and defeats, before Aegospotami and before the surrender of Athens. We don't have his completed account of the war's ending.

For those final years, another important source is Xenophon's Hellenica.

Xenophon begins where Thucydides' surviving narrative breaks off and continues the history of the Greek world beyond Athens' defeat.

The two writers aren't identical in their interests, methods or approach. That makes reading them alongside one another particularly worthwhile.

Xenophon gives us important accounts of events such as the naval battle of Arginusae in 406 BCE.

The Athenians won that battle, but the aftermath became a political controversy.

A storm had prevented the recovery of many shipwrecked men, and the Athenian commanders were subsequently accused of failing in their responsibilities.

Several generals were condemned and executed following proceedings whose legality was disputed.

It's another example of how military events and political decisions became inseparable during the war.

Then came 405 BCE. The Spartan commander Lysander confronted the Athenian fleet near Aegospotami.

The Athenians were caught in a vulnerable position, and most of their ships were captured.

It was the decisive naval disaster that brought us to the opening of this guide.

Without sufficient naval strength to secure its grain routes, Athens could not sustain its resistance indefinitely.

In 404 BCE, the city surrendered.

The war was over. But Athens' troubles were not.

Defeat did not end the suffering

Athens was allowed to survive as a city, but it had lost its empire and much of its former independence.

A Spartan-backed oligarchic government took power. Its members became known as the Thirty.

Their rule was marked by political persecution, confiscations and executions.

Athens had endured a generation of warfare only to find itself facing political violence at home.

In 403 BCE, the democracy was restored.

But the effects of the conflict remained.

Families had lost relatives and livelihoods. Communities across the Greek world had been destroyed or displaced. Longstanding alliances had been transformed.

Sparta had emerged as the leading Greek power, but victory brought problems of its own. Its position would be challenged by other states, including former allies. The rivalry between Greek communities did not disappear with the defeat of Athens.

Nor should we imagine that the war had simply ruined every part of Greek civilisation.

Literature, philosophy, political thought and intellectual debate continued. Some of the most important works of ancient Greek culture were written during or shortly after these troubled decades.

Socrates lived through the war. Aristophanes wrote comedies that reflected the anxieties and arguments of wartime Athens. Plato came of age in a city whose political world had been transformed by defeat.

The war forms part of the background to their lives and writings. Understanding it makes much of classical Greek history easier to understand.

Going deeper: warfare, politics and the way history is written

Once you know the broad story, the most interesting questions often become more specific.

Why did the Spartans struggle for so long to defeat Athens? Could Pericles' strategy have succeeded under different circumstances?

Was the Sicilian expedition an extraordinary mistake, or did it make sense to the Athenians who supported it?

And how much of our understanding depends on the way Thucydides chose to present events?

The books we've encountered offer different ways of investigating those questions. You might return to Lazenby for a closer examination of the military decisions, or to Cawkwell for a more critical reading of Thucydides. There's no need to work through every specialist study in a particular order.

For readers who want to investigate the construction of Thucydides' narrative itself, Carolyn Dewald's Thucydides' War Narrative: A Structural Study examines the structure of his history and how its presentation contributes to its meaning.

It's considerably more academic than the introductory books, so I wouldn't recommend it as a starting point. But it offers an interesting direction for someone who has already read Thucydides and wants to understand him as a historian and writer.

There are also ancient works that widen our understanding beyond political and military history.

Aristophanes' Lysistrata, first performed in 411 BCE, imagines women attempting to bring an end to the war.

It's a comedy, not a documentary account of ordinary Athenian life.

But it reminds us that the war existed in the imaginations and cultural lives of the people experiencing it, not only in the histories written about generals and politicians.

And Xenophon's Hellenica remains essential for following the final years that Thucydides did not complete.

Together, these works provide several ways of approaching the same conflict.

One explains the broad history. Another helps us understand the fighting. Others reveal the arguments, assumptions and limitations of the people who wrote about it.

A reading path through the Peloponnesian War

The war lasted twenty-seven years and involved much of the Greek world. There's no need to understand every campaign before exploring the books that interest you.

The following sequence offers a sensible route from the broad history into the ancient evidence and more specialised scholarship.

If you only want two books to begin with, Kagan and Thucydides will take you a long way.

Kagan helps you follow the war. Thucydides lets you encounter one of the ancient writers who lived through it and tried to understand why it happened.

The more specialised books become useful when particular questions begin to interest you.

The walls came down. The questions remained.

When Xenophon describes the destruction of Athens' walls in 404 BCE, he tells us that the victorious Peloponnesians celebrated what they believed was the beginning of freedom for Greece.

From their perspective, a powerful empire had been defeated.

But the Athenians had not spent twenty-seven years fighting because they believed themselves to be villains.

They had feared their enemies, defended their allies and argued that their security depended on preserving the power they had built.

Sparta, too, had reasons to fear the growing influence of Athens.

Other Greek communities had their own concerns, ambitions and grievances. Some chose sides willingly. Others discovered that the choices available to them were painfully limited.

That's part of what makes the Peloponnesian War so difficult to reduce to a simple story.

Athens was both a democracy and an imperial power.

Sparta claimed to defend Greek freedom while pursuing its own interests.

Both sides could point to legitimate fears, and both were capable of actions that devastated other communities.

Reading the war through Thucydides, Xenophon and modern historians doesn't give us one simple explanation for everything that happened.

It gives us a better understanding of the decisions people made, the pressures they faced and the consequences they did not always foresee.

And it takes us back to that night in Athens, when news of the loss of the fleet travelled from Piraeus towards the city.

For the people waiting behind the walls, the question was no longer how Athens could win the war.

It was what would happen when it finally lost.