The Peloponnesian War (431–404 BC)

After the Persian Wars, Athens became very rich and powerful. It had the biggest fleet, the στόλος, in Greece, and many island and coastal cities paid it money as its allies. Sparta, in the south of Greece, had the best soldiers on land and led its own group of allies in the Peloponnese. Each city was afraid of the other.

In 431 BC the war began. It is called the Peloponnesian War because Athens fought against Sparta and its allies from the Peloponnese. It lasted 27 years, with a break of a few years of uneasy peace, εἰρήνη. In most summers the Spartan army marched into the countryside around Athens and burned the fields. The Athenians stayed safe behind their long walls and sent their ships to attack the enemy coast.

Many terrible things happened: an illness killed many Athenians, cities were besieged, and a huge Athenian army was lost in Sicily. In 404 BC Athens, starving and without ships, surrendered to Sparta.

The historian Thucydides, an Athenian who lived through the whole war, separates the quarrels that were openly given as reasons from the real cause. The quarrels were about Corinth and its old colony Corcyra, about the city of Potidaea in the north, and about an Athenian decree that shut the city of Megara out of the markets of the empire. But the truest cause, he writes (1.23.6), was “the growth of the power of Athens, and the alarm which this inspired in Lacedaemon”, that is, in Sparta. The war broke the Thirty Years' Peace that the two sides had made about fourteen years earlier.

Pericles, the leading general, στρατηγός, of Athens, had a plan: avoid battles on land, bring the country people inside the walls, rely on the fleet and conquer nothing new (Thucydides 2.65.7). But in 430 BC a deadly epidemic, the λοιμός usually called the Plague of Athens, broke out in the crowded city (2.47). Doctors could do nothing, and many of them died themselves. Pericles died in 429 BC, two years and six months after the war began (2.65.6).

After Pericles, Thucydides says, the leaders of Athens were “more on a level with one another” and, each wanting first place, handed affairs over to the wishes of the crowd (2.65.10). The best known of them was Cleon. In 427 BC, after the island city of Mytilene revolted, he persuaded the assembly to vote to kill all its men; the next day the Athenians changed their minds and sent a second ship just in time. Thucydides calls him “the most violent man at Athens” (3.36.6).

In 425 BC the Athenians trapped Spartan soldiers on the island of Sphacteria, near Pylos. Here Thucydides (4.21.3) introduces Cleon as ἀνὴρ δημαγωγός, a leader of the people and the most persuasive with the crowd. Cleon promised to bring the Spartans back within twenty days, and he did. A year later, in his comedy Knights (424 BC), Aristophanes mocked a thinly disguised Cleon and joked that δημαγωγία was no longer a job for educated, decent men.

In 422 BC both Cleon and the Spartan general Brasidas died in battle at Amphipolis (5.10). Without them, the two sides signed the Peace of Nicias in 421 BC. Thucydides still counts it all as one war of 27 years (5.26).

The peace did not hold. In 416 BC Athens besieged the small island of Melos, which wanted to stay neutral, and after it surrendered killed its men and enslaved the women and children; Thucydides reports the talks before the siege, πολιορκία, as the famous Melian Dialogue (5.84–116). In 415 BC Athens sent a great expedition against Syracuse in Sicily. By 413 BC it had failed completely: at least 7,000 prisoners were held in the stone quarries, and “few out of many returned home” (7.87).

In the same year Sparta built a fort at Decelea in Attica, in sight of Athens, and kept an army there all year round (7.19). Persia, the old enemy, now paid for a Spartan fleet through the king's son Cyrus (2.65.12). In 405 BC the Spartan admiral Lysander caught the Athenian ships on the beach at Aegospotami and captured almost all of them (Xenophon, Hellenica 2.1.28).

Besieged and starving, Athens surrendered in 404 BC. It had to pull down its Long Walls and the walls of Piraeus and keep only twelve ships (Hellenica 2.2.20). Sparta installed the Thirty, remembered as the Thirty Tyrants, but democracy returned in 403 BC.