Peloponnesian War (431-404 BC): Athens Against Sparta

The Peloponnesian War was the long conflict fought from 431 to 404 BC between Athens, with its maritime empire, and Sparta, at the head of the Peloponnesian League. It drew in almost the entire Greek world, from Sicily to the coast of Asia Minor, and ended with the surrender of Athens. Thanks to the history written by Thucydides, it became one of the most closely studied wars in history, and a classic case study of rivalry between a rising power and an established one.

Background: two systems of power

After the Greek victories over Persia at Marathon in 490 BC and at Salamis and Plataea in 480-479 BC, the Greek world split into two blocs. Sparta, a land power with a superb army of citizen hoplites, led a loose alliance of mostly Peloponnesian states, including Corinth and later Thebes.

Athens took the lead in a new naval alliance against Persia, the Delian League, founded in 478 BC. Over the following decades Athens turned this league into an empire. Most members paid tribute in silver rather than supplying ships, and attempts to leave were crushed. The tribute paid for a large fleet of triremes, the fast oared warships of the age, and helped finance the building programme on the Acropolis under Pericles.

The two blocs had already clashed in the so-called First Peloponnesian War (c. 460-445 BC), which ended with the Thirty Years’ Peace of 446/445 BC. That treaty recognised the two alliances and provided for arbitration of disputes. It lasted less than half of its intended term.

Causes of the war

Thucydides drew a famous distinction between the stated grievances and the real cause. In his view, what made war inevitable was the growth of Athenian power and the fear it caused in Sparta. Modern historians still debate how far this judgment is correct, but the immediate disputes are clear:

• Corcyra (433 BC): Athens made a defensive alliance with Corcyra (Corfu), which was at war with its mother city Corinth, and Athenian ships took part in the Battle of Sybota against the Corinthian fleet.
• Potidaea (432 BC): Potidaea, a Corinthian colony that paid tribute to Athens, revolted, and Athens laid siege to it.
• The Megarian Decree (c. 432 BC): Athens excluded the neighbouring city of Megara from the harbours and markets of its empire, a severe economic blow.

Corinth and Megara pressed Sparta to act. In 432 BC the Spartan assembly voted that Athens had broken the peace. Pericles persuaded the Athenians to refuse Spartan demands, arguing that giving way on small points would only invite larger ones.

Course of the war

The Archidamian War (431-421 BC)

Fighting began in the spring of 431 BC, when Thebes, an ally of Sparta, made a surprise night attack on Plataea, an ally of Athens. Soon afterwards the Spartan king Archidamus II invaded Attica, the territory of Athens. The first ten years of the war are named after him.

Pericles’ strategy was to avoid a pitched battle with the stronger Spartan army. The rural population moved inside the city and the Long Walls that linked Athens to its port at Piraeus, while the fleet raided the Peloponnesian coast and kept the empire’s tribute and grain supply flowing. At the end of the first year Pericles delivered the Funeral Oration for the war dead, as recorded by Thucydides.

The overcrowded city was then struck by the Plague of Athens, which broke out in 430 BC and returned in 427/426 BC. It killed perhaps a quarter to a third of the population, including Pericles himself in 429 BC. Leadership passed to men such as Cleon, a forceful speaker who favoured a more aggressive policy, and the cautious Nicias.

The war then swung back and forth. Athens crushed a revolt on Lesbos in 427 BC, and in 425 BC Athenian forces captured some 120 full Spartan citizens at Pylos and Sphacteria, a shock to Spartan prestige. Sparta replied with the bold campaign of Brasidas in the north Aegean, who took the important Athenian colony of Amphipolis in 424 BC. The same year the Athenians were heavily defeated by the Boeotians at Delium. In 422 BC both Cleon and Brasidas were killed in a battle outside Amphipolis, removing the leading advocates of war on each side.

The Peace of Nicias and the Sicilian Expedition

In the spring of 421 BC the two sides agreed the Peace of Nicias, meant to last fifty years. It quickly proved hollow. Several of Sparta’s allies refused to accept it, Amphipolis was never handed back, and the young Athenian politician Alcibiades built an anti-Spartan coalition in the Peloponnese with Argos, Elis and Mantinea. Sparta defeated this coalition at the Battle of Mantinea in 418 BC.

In 416 BC Athens attacked the neutral island of Melos and, after a siege, killed its men and enslaved its women and children. Thucydides introduced the episode with the Melian Dialogue, a stark debate about power and justice.

In 415 BC the Athenians launched their most ambitious venture, the Sicilian Expedition against Syracuse. Alcibiades, one of its commanders, was recalled to face charges of sacrilege and defected to Sparta. The expedition ended in disaster in 413 BC: two great fleets and their crews were lost, Nicias and his fellow general Demosthenes were executed, and around 7,000 prisoners were held in the stone quarries of Syracuse.

The Decelean or Ionian War (413-404 BC)

On the advice of Alcibiades, Sparta occupied Decelea in Attica in 413 BC and kept a permanent garrison there. Athenians could no longer farm their land or work the silver mines at Laurium in safety, and Thucydides reports that more than 20,000 slaves deserted. Many of Athens’ subject cities in Ionia revolted.

Persia now joined the struggle. In return for recognition of Persian claims to the Greek cities of Asia Minor, Persian satraps (provincial governors), and from 407 BC the king’s younger son Cyrus, paid for Spartan fleets. Athens, short of money, was also divided at home. In 411 BC an oligarchic regime known as the Four Hundred briefly replaced the democracy before being overthrown.

Athens still won notable naval victories, at Cyzicus in 410 BC and at Arginusae in 406 BC. After Arginusae, however, the assembly put to death six of the victorious generals for failing to rescue survivors in a storm, an act many Athenians later regretted. Alcibiades, who had returned to Athenian service in 411 BC, went into exile again after a defeat at Notium in 406 BC.

The decisive blow came in 405 BC, when the Spartan commander Lysander surprised the Athenian fleet beached at Aegospotami in the Hellespont and captured almost all of it. Cut off from its grain supply from the Black Sea, Athens was blockaded by land and sea and surrendered in the spring of 404 BC.

Terms and aftermath

Corinth and Thebes wanted Athens destroyed, but Sparta refused to wipe out a city that had served Greece so well in the Persian Wars. Instead Athens had to pull down the Long Walls and the fortifications of Piraeus, hand over all but twelve ships, allow its exiles to return and follow Sparta’s lead in foreign policy.

A pro-Spartan oligarchy, the Thirty Tyrants, took power and carried out a reign of terror before democracy was restored in 403 BC. The restored democracy’s trial and execution of Socrates in 399 BC is often read against this bitter background.

Sparta’s victory proved short-lived. Its harsh rule over former Athenian allies, quarrels with Thebes and Corinth, and dependence on Persian gold led to new wars within a decade. Spartan land power was finally broken by Thebes at the Battle of Leuctra in 371 BC.

By the numbers

Key people

• Pericles (c. 495-429 BC): the leading Athenian statesman at the outbreak of war and architect of its defensive strategy.
• Archidamus II (reigned c. 469-427 BC): the Spartan king who led the early invasions of Attica despite having warned against the war.
• Brasidas (died 422 BC): the most enterprising Spartan commander of the first phase, famous for his campaign in Thrace.
• Alcibiades (c. 450-404 BC): brilliant and unpredictable, he served Athens, Sparta and Persia in turn.
• Lysander (died 395 BC): the Spartan admiral who won Aegospotami and imposed the peace terms on Athens.
• Thucydides (c. 460-c. 400 BC): an Athenian general exiled after failing to save Amphipolis, who wrote the war’s history.

Timeline

• 433 BC: Athens allies with Corcyra; Battle of Sybota.
• 431 BC, spring: Thebes attacks Plataea; Archidamus invades Attica.
• 430 BC, summer: the plague breaks out in Athens.
• 425 BC, summer: Athenians capture Spartan hoplites on Sphacteria.
• 421 BC, spring: the Peace of Nicias is concluded.
• 415-413 BC: the Sicilian Expedition ends in Athenian catastrophe.
• 413 BC: Sparta fortifies Decelea in Attica.
• 411 BC: oligarchic coup of the Four Hundred in Athens.
• 405 BC: Lysander destroys the Athenian fleet at Aegospotami.
• 404 BC, spring: Athens surrenders; the Long Walls are demolished.

Legacy

Thucydides wrote his history, he said, as a “possession for all time”, meant to help readers understand future events that would resemble those of the past. His analysis of fear, ambition and self-interest in politics made him a founding figure for the study of international relations, and his account is still read in military colleges and universities.

The war also shaped Greek culture. The comedies of Aristophanes and the tragedies of Euripides reflect the strain of the long struggle, while the defeat of the democracy fed the doubts about popular rule found in the works of Plato. The phrase “Thucydides Trap”, coined in the 2010s by the political scientist Graham Allison, uses the war as an analogy for modern great-power rivalry, although classicists argue about how well the comparison fits.

Why it matters

The Peloponnesian War ended the age of Athenian greatness and weakened the Greek city-states for good. Within seventy years they would fall under the power of Macedon. Its historian left one of the most influential works of political thought ever written, and the questions he raised about power, democracy and war remain central to how people think about conflict today.