The main event was the Sicilian Expedition, between 415 and 413 BC, during which Athens lost almost all its navy in the attempt to capture Syracuse, an ally of Sparta.

With Persian money, Sparta built a massive fleet under the leadership of Lysander, who won a streak of decisive victories in the Aegean Sea, notably at Aegospotamos, in 405 BC.

The economic costs of the war were felt all across Greece, poverty became widespread in the Peloponnese, while Athens was devastated and never regained its pre-war prosperity.

The conflict between democratic Athens and oligarchic Sparta, each of which supported friendly political factions within other states, made war a common occurrence in the Greek world.

Ancient Greek warfare, originally a limited and formalized form of conflict, was transformed into an all-out struggle between city-states, complete with mass atrocities.

Shattering religious and cultural taboos, devastating vast swathes of countryside, and destroying whole cities, the Peloponnesian War marked the dramatic end to the fifth century BC and the golden age of Greece.

[5] A partial exception are the lengthy speeches he reports, which Thucydides admits are not accurate records of what was said, but his interpretation of the general arguments presented.

Born in Athens, Xenophon spent his military career as a mercenary, fighting in the Persian Empire and for Sparta in Asia Minor, Thrace and Greece.

The Roman-Greek historian Plutarch wrote biographies of four of the major commanders in the war (Pericles, Nicias, Alcibiades and Lysander) in his Parallel Lives.

Its empire began as a small group of city-states, called the Delian League – from the island of Delos, on which they kept their treasury – that formed to ensure that the Greco-Persian Wars were over.

Athens had greatly increased its own power; a number of its formerly independent allies were reduced, over the course of the century, to the status of tribute-paying subject states of the Delian League.

[8] When the rebellious helots were finally forced to surrender and permitted to evacuate the state, the Athenians settled them at the strategic city of Naupaktos on the Gulf of Corinth.

A 15-year conflict, commonly known as the First Peloponnesian War, ensued, in which Athens fought intermittently against Sparta, Corinth, Aegina, and a number of other states.

At the Battle of Sybota, a small contingent of Athenian ships played a critical role in preventing a Corinthian fleet from capturing Corcyra.

[11] In response, the Athenians reminded the Spartans of Athens's record of military success and opposition to Persia, warned them of confronting such a powerful state, and encouraged Sparta to seek arbitration as provided by the Thirty Years' Peace.

[14] Sparta and its allies, except for Corinth, were almost exclusively land-based, and able to summon large armies which were nearly unbeatable (thanks to the legendary Spartan forces).

The Spartans also occupied Attica for periods of only three weeks at a time; in the tradition of earlier hoplite warfare, the soldiers were expected to go home to participate in the harvest.

The fear of plague was so widespread that the Spartan invasion of Attica was abandoned, their troops being unwilling to risk contact with the diseased enemy.

Athens stretched their military activities into Boeotia and Aetolia, quelled the Mytilenean revolt and began fortifying posts around the Peloponnese.

The Athenians jailed Sphacterian hostages in Athens and resolved to execute the captured Spartans if a Peloponnesian army invaded Attica again.

After these battles, the Spartan general Brasidas raised an army of allies and helots and marched the length of Greece to the Athenian colony of Amphipolis in Thrace.

Emboldened, the Argives and their allies, with the support of a small Athenian force under Alcibiades, moved to seize the city of Tegea, near Sparta.

In the battle, the allied coalition scored early successes, but failed to capitalize on them, which allowed the Spartan elite forces to defeat them.

With the treasury and emergency reserve of 1,000 talents dwindling, the Athenians were forced to demand even more tribute from her subject allies, further increasing tensions and the threat of rebellion within the Empire.

He sent his son Cyrus the Younger into Asia Minor as satrap of Lydia, Phrygia Major and Cappadocia, and general commander (Karanos, κἀρανος) of the Persian troops.

In him, Cyrus found a man willing to help him become king, just as Lysander himself hoped to become absolute ruler of Greece by the aid of the Persian prince.

[21][22][23] Cyrus the Younger would later obtain the support of the Spartans in return, after having asked them "to show themselves as good friend to him, as he had been to them during their war against Athens", when he led his own expedition to Susa in 401 BC in order to topple his brother, Artaxerxes II.

[24] The faction hostile to Alcibiades triumphed in Athens following a minor Spartan victory by their skillful general Lysander at the naval battle of Notium in 406 BC.

However, the Spartans announced their refusal to destroy a city that had done a good service at a time of greatest danger to Greece, and took Athens into their own system.

[31] Although the hegemony of Athens was broken, the Attic city completed the recovery of its autonomy in the Corinthian War and continued to play an active role in Greek politics.