• James Houser

431 BC - The Peloponnesian War Begins

Updated: Jun 14, 2021

October 12. 431 BC. Once they stood together against the Great King of Persia. King Leonidas had died fighting at Thermopylae, while Themistocles had saved the Greeks at Salamis. They could not have won without each other. After decades of worsening relations, though, the cities of Athens and Sparta have come to blows. The war they fight, a war like no other, will end Classical Greece and tear the Hellenes apart. The Peloponnesian War has come.

We know the Peloponnesian War better than almost any ancient or medieval conflict. We have a single man to credit for this: Thucydides. The Athenian historian and author of the landmark history can reasonably be described as the first real historian, the man who actually investigated and dug into historical documents and records to understand what had happened to his country. He interviewed people from all sides of the conflict, gave a fair hearing to both sides, and finished a work that is more critical, reflective and hard-hitting than many works of history produced today. In an age when most historical works were propaganda, hearsay or near-legendary, Thucydides looked for the truth. That, among other things, is what made the Peloponnesian War a war like no other.

But it was more than that. Thanks to what we know about the Peloponnesian War, the great war between Athens and Sparta, we can discern the great questions of power, diplomacy, leadership and war that still haunt us to this day. Thucydides gives us our first window into a democracy at war: its internal struggles, the popular mood, the role of a charismatic leader and the dangers of faction. There are philosophical debates about the role of great powers and how they should protect the weak. There are grand strategic debates: how much should we commit to this strategy? What do we do after our initial plan didn’t work? Should we strike at their weak point or their strong point? What will our people think of this strategy? Will the other powers get involved, and on whose side? All are relevant questions that leaders have pondered in our own day.

But the war was not only a mirror for us, looking back from the future: it was devastating to the Greek world. Economies were ruined, political life radicalized and destroyed, peoples annihilated. Countries were laid waste, cities burned, monuments ruined. As the struggle dragged on, virtually every religious or culture taboo about the conduct of war was broken. The war became not just a conflict over power structures of spheres of influence, but a struggle for survival in which everything was at stake. The Greek world tore itself apart in thirty years of conflict, leaving it open to later domination by Macedon and Rome. The Peloponnesian War ended the golden age of Classical Greece once and for all.

How did it begin? How did a Greek world that had been united in the face of the Persian invasion, that had stood together at Thermopylae and Salamis and Plataea, come to this? Thucydides’ explanation was succinct and straight: “The growth of the power of Athens, and the alarm which this inspired in Sparta, made war inevitable.” Fear, then, was the answer. Athens grew strong, and this made Spartans afraid.

The story has to begin at the end of the Persian invasion. In 479 BC, a combined Greek land army destroyed the last remnants of the Persian invasion force at the Battle of Plataea. At the same time, the victorious Greek fleet that had won the battle of Salamis followed up its victory by crossing the Aegean and destroying the rest of the Persian fleet at Mycale. Though Xerxes had already returned to the Persian capital to contain the fallout from his failed invasion, these two battles spelled the end of open Persian invasion of Greece.

Up to this point, the Spartans had led the Greek alliance. Sparta was universally seen as the most militaristic and warlike of the Greek states, and for ample reasons that I’ve covered before. However, the Spartans felt like their mission had been accomplished. The Persians had been kicked out of mainland Greece, their army and fleet had been destroyed, and that was that.

The outstanding issue was the Ionians. There were still dozens of Greek cities stretched over the Aegean islands and the west coast of Asia that were still ruled by the Persians, and the Athenians wanted to go liberate those settlements. The Spartans disagreed, fearing that providing long-term security for these cities would be impossible, and instead proposed that the Greeks under Persian rule be evacuated to mainland Greece. The Athenians refused, and vowed to continue the war against Persia to achieve the freedom of the Greeks.

Athens, from here on out, took command of the alliance against Persia as Sparta withdrew its forces back home. Most of the other Greek mainland cities such as Corinth and Thebes followed the leader, leaving Athens and a few other coastal and seafaring cities as the only remaining members of the anti-Persian coalition. Undeterred, Athens called a congress on the holy island of Delos to found a new alliance, explicitly led by Athens and determined to liberate the Greeks and gain revenge on the Persians. This new alliance was called the Delian League.

The Delian League basically boiled down to “Athens and friends,” since it consisted mainly of small island or coastal towns led by the massive battle fleet that Athens had built under the guidance of Themistocles. One of the primary clauses in the alliance, though, required member cities to either pay a large tax to the League treasury or contribute men and ships to the alliance. While any city that was threatened by Persia wanted to be part of the league, many of them were too weak to supply men and found it much easier to pay the tax. League members shared a foreign policy and pooled their resources to fight the Persians.

As the war against the Persians continued, Athens and its Delian League racked up victory after victory, expelling the Persians from Greek cities and adding them to the league. As Athens fought for the freedom of the Greeks, however, some cities realized that the power balance was starting to shift. The concentration of the League’s wealth in the hands of Athens gave it disproportionate power to the rest of the League, especially after 454 BC when the site of the treasury was moved from Delos to Athens.

When cities decided they wanted to leave the league, or rebel against Athens, they would find themselves overrun by Athenian troops, their walls torn down and their status reduced to that of vassal states. The Athenians had soon defeated the Persians thoroughly – but they did not dissolve the League. It became clear that Athens was no longer the leader of an alliance, but the ruler of an empire.

None of this was directed at Sparta, or its own league of cities known as the Peloponnesian League. But as time went on, it became harder and harder for Sparta to ignore the growing power of Athens and its empire. In 465 BC, one of the rebelling cities of the league asked Sparta for assistance, but the Spartans turned them down. One of the main reasons was that they were facing the greatest slave rebellion in their history. Sparta asked for assistance from all the other Greek cities, including Athens; when Athens sent troops, however, the Spartans dismissed their force but allowed every other army to remain. The Spartans, according to Thucydides, feared that the Athenians would side with the slaves. Athens took this as an insult and finally broke off its old alliance with Sparta, and even took in the escaped slaves that had rebelled against Spartan power.

Sparta saw its influence over the Greek world begin to wane in favor of Athens, and this caused fear and discomfort. As their mutual spheres of influence began to collide, tensions began to flare up between the Peloponnesian and Delian Leagues. While Athens had more or less total control over the actions of its subject cities, the Spartans held more of a “first among equals” position in the Peloponnesian League, so they found it more difficult to restrain their allies. The Athenians had begun to make alliances with old Spartan enemies such as Argos, Sparta’s longtime rival city in southern Greece, and Megara, a city in a critical strategic location on the narrow land passage between the Peloponnesus and Athens’ homeland. Megara had recently come into conflict with Sparta’s primary ally Corinth, and this city became a flashpoint.

The series of low-intensity conflicts known as the First Peloponnesian War, from 460 to 445 BC, erupted from these separate conflicts. Athens and Corinth came into conflict over the domination of Megara, and Athens allied with Argos because Argos feared Sparta’s strength. The war was marked by Spartan successes on land and Athenian successes at sea, without any real conclusions. Nothing was settled by the First Peloponnesian War, which was really a halting series of separate conflicts, and to settle the issue both sides signed the Thirty Years’ Peace in 445 BC. It would not last thirty years.

For Athens, this was their true Golden Age. Much of the greatness of Greek high culture – the dramas, literature, poetry and art – was constructed during the period before the Peloponnesian War truly began. Though Athens was a democracy, the first of its kind, it was dominated by the charismatic leadership of a citizen named Pericles. Pericles oversaw this period of Athenian greatness, and made Athens a city of monuments, temples, and great structures, including the Parthenon that still stands today. This glory was paid for, of course, by the funds of the Delian League – which had once been an alliance to fight Persia, and was now an Athenian Empire that existed to enrich and beautify Athens. This caused no small resentment among the subject cities.

The Thirty Years’ Peace came under its first great test in 440 BC, when the city of Samos rebelled against the Delian League. They gained support from the Persians, and soon a broader outbreak of revolts broke out against Athens. The Spartans gathered the Peloponnesian League to debate whether or not they should help the rebels, but the League’s cities were still uncertain about the prospects of war, and they stood by as Athens crushed the rebellions. But the prospect was there. It was clear that it would take only a single trigger for the two Leagues to move into open war. The question was where, and how?

For the Greek cities, events had come to this because of the newly resurgent power of Athens. Athens had ascended to a position of power than no single Greek city had ever achieved, and this growing sphere of influence began to intrude on the long-held privileges and preserves of other cities. By the enormous reach of their fleet and their newfound willingness to bring anyone into their alliance no matter how provocative, Athens was stepping in on a lot of turf. The Greek cities of the mainland felt more and more constricted. The growing belief was that Athens was slowly strangling them – peacefully, quietly, but inevitably. They had to act before it was too late.

Corinth, a member of Sparta’s Peloponnesian League, was having issues with its colony of Corcyra. Corcyra was a Greek city situated on Corfu, a far-flung island closer to Italy than to mainland Greece. Corcyra had built its own large fleet in an attempt to break free of Corinthian influence, but Corinth was preparing an expedition to reassert their claims over Corcyra. In desperation, in 433 BC Corcyra asked to join the Delian League. Athens accepted the offer, sending a small force of ships to protect Corcyra. When the Corinthian and Corcyran fleets joined battle, Athens took part – initiating hostilities with Corinth.

Corinth was furious, and began to secretly send troops to assist the neverending rebellions against Athenian hegemony – including the critical city of Potidaea in upper Greece. The Athenian intervention at Corcyra was in a diplomatic grey area, and reasonable people could disagree as to whether or not this violated the Thirty Years’ Peace. The Corinthian intervention at Potidaea, though, was a clear violation of the Peace. Athens doubled down by restricting Peloponnesian trade through the Delian League, which was basically a declaration of economic warfare. While this was only meant to put pressure on Corinth, it aroused fears in the other Greek cities – if Athens could do this, what else could they do?

Finally, under pressure from the Corinthians, in 432 BC the Spartans called an assembly of the Peloponnesian League to discuss what actions they should take in the face of Athenian provocations and hostility. Uninvited, a delegation of Athenians also showed up, and soon debates broke out between all sides. The Corinthians lambasted Sparta for their inactivity, claiming that if they continued to sit on their hands while Athens horned in on everyone’s territory, their own alliance would leave them behind. The Athenians warned Sparta of their power and strength, urging them to accept mediation. This last bit probably provoked the Spartans – Athens was too strong to be toyed with, and could not be allowed to threaten them into peace. Sparta declared war, and both Leagues joined their leaders. The Peloponnesian War was on.

Pericles rallied Athens in the face of Sparta’s declaration of war, preparing his people for the great conflict. Pericles was one of the great orators and democratic war leaders of history; his “Funeral Oration” given in 431 BC, at the height of the war, is one of history’s great speeches. Pericles was aware that Spartan armies would soon show up to ravage Athens’ territory and destroy their farms and olive groves. His strategy was simple, but devastating. Right after the Persian invasion, Athens had built the “Long Walls”, a narrow corridor of stone walls connecting the great city of Athens with its seaport of Piraeus. This combination of walls and corridor looked something like a baby’s rattle. As long as Athens could maintain command of the sea and stay within its walls, the city could be fed and supplied, no matter what Sparta did outside the walls.

So Athens’ citizens had to watch, year after year, as the Spartan armies marched into the Athenian heartland and burned their homes, farms, and ancestral graves. The black smoke rose as the Athenians looked out from their walls. But Sparta could not penetrate the walls, having no siege weaponry or the ability to maintain an army for so long; Athens could not challenge the mighty Spartan and allied army. Because the Spartan hoplites would be needed at home for harvest and to prevent further slave rebellions, they could not stay and occupy Athenian territory; the longest any invasion ever lasted was for 41 days. Thus it was a stalemate.

In the meantime, as the people and army of Athens holed up within their walls, their navy ruled the seas. This would be the rule for most of the war: Sparta dominant on land, Athens dominant on the waves. The elephant versus the whale, if you will. Athens cut off the Peloponnesians from foreign trade and luxuries, which greatly hurt some of the main trading cities like Corinth and Megara. The Peloponnesians did not have a fleet large enough to challenge Athens; on the rare occasions that they did, like the battles of Naupactus and Rhium in 430 and 429 BC, the Athenians used clever tactics and formations to smash them. The Spartans may have had Athens under siege, but Athens had Greece under siege.

As their farms continued to be pillaged, year after year, Athens began to experience a decline in morale if not commitment. Soon many began to express discontent towards Pericles, who they blamed for having led them into war. Nevertheless, Pericles refused to divert from his course, believed his strategy of indirect warfare would eventually gain a renewal of the peace for Athens. Pericles did not aim to destroy Sparta or the Peloponnesian League, but simply to tire them out and force a settlement. He rallied support in Athens with his famous “Funeral Oration” in 431, which honored the fallen dead and reminded Athens of their democracy and the values for which Athenian soldiers had died. The war would continue.

During the first years of the war, Athenian culture was still in high flower, and some of the great Greek dramas were produced, among them Sophocles’ “Oedipus Rex” in 429 BC. It was at the height of the Peloponnesian War that one of my favorite stories from the ancient world occurred. The playwright Aristophanes, no friend of Pericles, had written a play called the Archarnians which premiered in 427 BC. It harshly criticized the war, humiliated Pericles, and called for an end to hostilities. Aristophanes premiered his play on the Acropolis, the highest point in Athens, and as his actors performed the people of Athens could see the Spartans raging across their lands and see the smoke rising. It was a powerful combination of a cultural critique of an unpopular war alongside the very visible effects of that war. How many other conflicts have seen this blatant juxtaposition of satire and harsh reality?

What happened next is even more astounding. The Athenian assembly voted Aristophanes the first prize in drama that year for his harsh criticism of the war, a play in which he called them all fools for continuing this terrible conflict. Then…THEN!...they held a grand assembly in which they voted…to continue the war. A strange people, these Athenians…but not so strange, if you look at America today. We too are capable of sustaining paradoxes within our democracy.

But the Peloponnesian War had just begun. In 430 and 429 BC, Athens was ravaged by a great plague, which not only devastated their tightly packed population but also killed Pericles himself. Without his restraining hand, the masses of Athens grew more aggressive, and more committed to not just ending the war, but winning it. Starting in 428 BC, Athens would go on the offensive. The war like no other, a war with no equivalent in Greek history, was only getting wound up.

Keep an eye out for my next installment: the next part in my last great planned series in this “year of military history.”

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