Thermopylae was a defeat. The Persians marched south, burned Athens and seemed on the edge of conquering Greece. Within a year, however, the Greeks had won. Sparta went on to defeat Athens in a long war and became the dominant power in Greece, only to collapse within a generation.

Salamis and Plataea

After Thermopylae, the Athenians evacuated their city, and the Persians burned it, including the temples on the Acropolis. But in September 480 BCE, in the narrow straits near the island of Salamis, the Greek fleet, led in practice by Themistocles and the Athenian navy, destroyed much of the Persian fleet. Xerxes returned to Asia, leaving his general Mardonius with an army in Greece.

In 479 BCE, at the Battle of Plataea, the largest Greek army ever assembled, led by the Spartan regent Pausanias, defeated Mardonius, who was killed. Spartan hoplites played the decisive role. On the same day, according to tradition, the Greeks also defeated a Persian force at Mycale in Ionia. Persia would never again invade mainland Greece. Herodotus called Plataea the finest victory he knew of.

Rivalry with Athens

After the Persian Wars, Athens used its navy to build an alliance, the Delian League, which gradually became an Athenian empire. Sparta, wary of commitments far from home and of its helots, mostly stayed in the Peloponnese. Tension grew between the land power and the sea power. In 431 BCE the Peloponnesian War began. Thucydides, its great historian, concluded that the real cause was Sparta's fear of Athens's growing power.

Sphacteria

In 425 BCE, Athenian forces trapped a group of Spartan soldiers on the island of Sphacteria, off the coast of Messenia. After a long siege and fighting, 292 men surrendered, about 120 of them full Spartan citizens. The Greek world was stunned. Spartans were supposed to die rather than surrender. Thucydides reports an Athenian ally mockingly asking a captured Spartan whether the brave ones had all died. The prisoner replied that an arrow would be worth a great deal if it could pick out the brave, meaning that death in battle was a matter of chance. The episode damaged the myth of Spartan invincibility.

Victory with Persian gold

Sparta eventually won the Peloponnesian War, but only by building a navy, which it financed with money from Persia, its old enemy, in return for promising to return the Ionian Greek cities to Persian control. The Spartan commander Lysander destroyed the Athenian fleet at Aegospotami in 405 BCE, and Athens surrendered in 404 BCE. Sparta installed the Thirty Tyrants in Athens, a brutal oligarchy that lasted only months.

Hegemony and its problems

Sparta now dominated Greece, but it governed its new power poorly. Its commanders installed narrow, often harsh governments in other cities. Its leaders grew rich from war, despite Spartan traditions against wealth. Allies resented Spartan arrogance. Within a few decades Sparta faced coalitions of its former allies and enemies.

The shrinking citizen body

Sparta's deepest problem was demographic. The number of full citizens, the Spartiates, fell steadily. Herodotus suggests there were about eight thousand at the time of the Persian Wars. By the time of Aristotle, in the fourth century BCE, he reported that there were fewer than one thousand. Greeks called this shortage of men oliganthropia. Causes included losses in war and the earthquake of 464 BCE, the concentration of land in fewer hands, and rules that stripped citizenship from anyone who could not pay mess dues. Sparta rarely admitted new citizens, so the elite shrank while the helots remained.

Leuctra

The end of Spartan power came suddenly. In 371 BCE, at the Battle of Leuctra, the Theban general Epaminondas used an innovative tactic: he massed his best troops on one wing, many ranks deep, and smashed the Spartan right wing, where their best soldiers stood. About four hundred of the seven hundred Spartiates present were killed, along with King Cleombrotus. Soon afterward, Epaminondas invaded Laconia and, in 369 BCE, freed Messenia, founding the city of Messene for the former helots. Without Messenia's land and labor, Sparta never recovered its former power.

Later Sparta

Sparta survived as a minor power. In the third century BCE, reforming kings Agis IV and Cleomenes III tried to restore the old system by canceling debts and redistributing land, but their reforms failed. Under the Roman Empire, Sparta became a tourist attraction, where visitors watched staged displays of Spartan endurance, including the ritual whipping of youths at the sanctuary of Artemis Orthia, where an amphitheater was built for spectators.

Worked example: why did Sparta decline?

List the causes of Sparta's decline and judge which mattered most.

• Too few citizens. Strict rules kept the elite small and let it shrink further.
• Dependence on helots. When Messenia was freed, the economic base collapsed.
• Rigidity. Sparta's system resisted change, and its leaders struggled to adapt to new tactics and wider responsibilities.
• Corruption by success. Victory brought wealth and power that Spartan institutions were not designed to handle.

Most historians would stress the first two, which were linked: Sparta's way of life rested on a small citizen body ruling a large enslaved population, and it could not survive the loss of either. A society that refuses to widen its circle of citizens can be formidable for a time but brittle over the long run.