The two most powerful city-states in ancient Greece, Athens and Sparta, went to war with each other from 431 to 405 B.C. The Peloponnesian War marked a significant power shift in ancient Greece, favoring Sparta, and also ushered in a period of regional decline that signaled the end of what is considered the Golden Age of Ancient Greece.

The Cause of the Peloponnesian War

The formation of the Delian League, or Athenian League, in 478 B.C. united several Greek city-states in a military alliance under Athens, ostensibly to guard against revenge attacks from the Persian Empire. In reality, the league also granted increased power and prestige to Athens. The Spartans, meanwhile, were part of the Peloponnesian League (550 BC- 366 B.C.) of city-states. It was only a matter of time before the two powerful leagues collided.

The Great Peloponnesian War, also called the First Peloponnesian War, was the first major scuffle between them. It became a 15-year conflict between Athens and Sparta and their allies. Peace was decreed by the signing of the Thirty Years Treaty in 445 B.C., effective until 437 B.C., when the Peloponnesian War began.

A civil war in the obscure country of Epidamnus led to the involvement of Sparta’s ally, Corinth. When Sparta was brought in to be part of conflict negotiations, Corinth’s longtime enemy Corcyra targeted Epidamnus and seized it in a naval battle. Corinth retreated to rebuild its fleet and plan retaliation.

Did you know? The Athenians experienced a major setback when a plague broke out in 430 B.C. Between one-third and two-thirds of the Athenian population died, including the prominent general Pericles.

The Peloponnesian War Begins

In 433 B.C. the tension continued to build and Corcyra officially sought Athens’ support by arguing that conflict with Sparta was inevitable and Athens required an alliance with Corcyra to defend itself. The Athenian government debated the suggestion, but its leader Pericles suggested a defensive alliance with Corcya, sending a small number of ships to protect it against Corinthian forces.

All forces met at the Battle of Sybota, in which Corinth, with no support from Sparta, attacked and then retreated at the sight of Athenian ships. Athens, convinced it was about to enter war with Corinth, strengthened its military hold on its various territories in the region to prepare.

Sparta was hesitant to enter the war directly, but was eventually convinced by Corinth to do so, though this was not a popular decision among Sparta’s other allies. A year passed before Sparta took aggressive action. During that time, Sparta sent three delegations to Athens to avoid war, offering proposals that could be viewed as a betrayal of Corinth. These efforts conflicted with Pericles’ agenda and the Athenians rejected peace.

Athens vs. Sparta

The first 10 years of the conflict are known as “Archidamian War,” after Spartan King Archidamus. The Spartan slogan for that period was “Freedom for the Greeks,” and its stated aim was to liberate the states under Athenian rule by destroying its defenses and dismantling its structure.

As Spartan forces surrounded Athens in a siege, decimating the countryside and farmland, Pericles declined to engage against them near the city’s walls, instead leading naval campaigns elsewhere. He returned to Athens in 430 B.C. as a plague ravaged the city, killing nearly two-thirds of the population. Pericles, following a political uprising that led to his censure, succumbed to the plague in 429 B.C., fracturing the Athenian leadership. Despite this major setback for the Athenians, the Spartans saw only mixed success in their war efforts, and some major losses in western Greece and at sea.

The Peace of Nicias

In 423 B.C., both sides signed a treaty known as the Peace of Nicias, named for the Athenian general who engineered it. Meant to last 50 years, it barely survived eight, undermined by conflict and rebellion brought on by various allies.

Second Phase of War

War reignited decisively around 415 B.C. when Athens received a call to help allies in Sicily against invaders from Syracuse, where an Athenian official defected to Sparta, convincing them that Athens was planning to conquer Italy. Sparta sided with Syracuse and defeated the Athenians in a major sea battle.

Who Won the Peloponnesian War?

Athens did not crumble as expected, winning a string of naval victories against Sparta, which sought monetary and weapons support from the Persian Empire. Under the Spartan general Lysander, the war raged for another decade. By in 405 B.C. Lysander decimated the Athenian fleet in battle and then held Athens under siege, forcing it to surrender to Sparta in 404 B.C.

Impact of the Peloponnesian War

The Peloponnesian War marked the end of the Golden Age of Greece, a change in styles of warfare and the fall of Athens, once the strongest city-state in Greece. The balance in power in Greece was shifted when Athens was absorbed into the Spartan Empire. It continued to exist under a series of tyrants and then a democracy. Athens lost its dominance in the region to Sparta until both were conquered less than a century later and made part of the kingdom of Macedon.


The Peloponnesian War by Nigel Bagnall, published by St Martins Press, 2004.

The Peloponnesian War by Donald Kagan, published by Viking Penguin, 2003.

Ancient Greece: From Prehistoric to Hellenistic Times by Thomas R. Martin, published by Yale University Press, 1996.


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