Thucydides claims the Peloponnesian War is the greatest event or movement in human history, and the most important part of this great war takes place in Books VI-VII: The ill-fated Sicilian Expedition.
The Sicilian Expedition represents the turning point in the war. Thucydides begins to explain the expedition by offering a history of the origins of Sicily and its people. He continues by discussing the current zeitgeist in Athens. A rising and powerful love of Athens or a fervent patriotism arises among the Athenians. The old, middle-aged, and young citizens all see an easy occupation of Sicily that will yield great riches and power (i.e. the old and young, rich and poor are all united in support of the expedition as is necessary for an empire), while the skeptics are forced into silence for fear of being unpatriotic.
Thucydides offers two contrasting views on the Sicilian proposition: Nicias, the sober-minded Athenian general (or strategos) who is fervently opposed to interventionism. Nicias was the voice for moderation in Athens. Nicias had negotiated the aptly-named Peace of Nicias previously in 421 BC which paused the ongoing conflict between Athens and Sparta until the Athenian Sicilian Expedition 421 BC.
In contrast to Nicias’s moderation, Thucydides also shows us Alcibiades, the demagogic follower of Socrates and bombastic son of the old Athenian aristocracy, who successfully takes up the mantel of Pericles. Alcibiades rouses the passions of the Athenian public by claiming an either/or situation with regard to Sicily. The choice is between conquering or being conquered, though the idea that Athens is facing imminent conquest is absurd. Alcibiades is a proponent of aggressive expansionism and, in the end, he wins the day and leads the expedition to Sicily. Consider the way Thucydides describes the general mood of the Athenians regarding the invasion of Sicily:
“Everyone fell in love with the enterprise. The older men thought that they would either subdue the places against which they were to sail, or at all events, with so large a force, meet with no disaster; those in the prime of life felt a longing for foreign sights and spectacles, and had no doubt that they should come safe home again; while the idea of the common people and the soldiery was to earn wages at the moment, and make conquests that would supply a never-ending fund to pay for the future. With this enthusiasm of the majority, the few that did not like it feared to appear unpatriotic by holding up their hands against it, and so kept quiet” (6.24).
According to Thucydides, there is a kind of erotic love for conquest that grips the people of Athens, and the ‘tyranny of the majority’ as Madison would have called it, takes hold. However, this eroticism takes different forms depending upon age and station: the older men thought their army was so powerful it could not possibly be defeated, those in the prime of their lives were longing for adventure (new things, ‘foreign sights and spectacles’), and the common people and soldiery were hungry for riches and security. In war, each group sees their own deprivation as an opportunity: strength, adventure, and riches, respectively.
At any rate, as happens with the superstitions of crowds, on the eve of the Sicilian Expedition all the stone statues of Hermes, the “Hermae,” are mutilated throughout the city of Athens. And rumors surface about drunken parties in private homes where the Mysteries of profaned (for reference see Socrates in Plato’s Symposium). Immediately, Alcibiades is blamed and it bears a foreboding sign for the expedition, while the enemies of Alcibiades hope to elevate the rule of the People, rather than leaders like Pericles and Alcibiades. These leaders win the moment and Alcibiades is brought to trial but he flees in exile to Sparta -his allegiances now in question, Alcibiades defects to the enemy. Meanwhile, the Sicilian Expedition ends in disaster as the Athenian invasion fails to claim ground, and all the retreating Athenians are slaughtered in Syracuse.
Later, Thucydides makes note of the foremost cause of ruin for the Athenian army:
“Indeed the first and foremost cause of the ruin of the Athenian army was the capture of Plemmyrium [a harbor port near Syracuse where the Athenians retreated], even the entrance of the harbor being now no longer safe for carrying in provisions, as the Syracusan vessels were stationed there to prevent it, and nothing could be brought in without fighting; besides the general impression of dismay and discouragement produced upon the army” (7.24).
In response, Athens votes to send a massive force of reinforcements led by the general Demosthenes, not be confused with the great Athenian orator and speechwriter, but the Athenian armies become separated, decimated, enslaved, starved, and both Demosthenes and Nicias are executed. A few Athenian prisoners escape to deliver the dismal news back home in Athens.
Timeline of Events in the Peloponnesian War:
6th-5th Centuries BC: The Peloponnesian League is created and led by Sparta over the surrounding Peloponnesus: Corinth, Elis, Tegea, and others. Also the Delian League was created under the leadership of Athens.
435 BC: The city of Epidamnus, a colony of Corcyra located right at the entrance to the Ionic Gulf, undergoes an internal revolt and requests help from Corcyra which is denied so they request help from soft rival to Corcyra, Corinth. It causes a proxy war between Corinth and Corcyra, with Corcyra winning back its colony. In response Corinth begins building up a vast navy.
433 BC: Both Corinth and Corcyra call upon Athens, a fellow member of the Delian League, for aid. After both making their cases, Athens votes with an eye toward war with the Peloponnesus by siding with Corcyra. However, when both sides do battle, Corinth wins the day so they send reinforcements and the escalation calls upon the Peloponnesian League to break the standing peace treaty.
432 BC: Athens fortifies its new ally Corcyra against Corinthian forces at Potidaea, as well. The Siege of Potidaea brings an end to Sparta’s inaction, with many denouncing Athens. Athens sent a fleet to Potidaea after Sparta and allies encouraged a revolt on the island in response to Athenian support for Corcyra against Corinth. Sparta declares Athens to be the aggressor and declares war on Athens.
The powerful orator Pericles rises in Athens who is vehemently opposed to any conciliation with Sparta, in contrast to Archidamus King of Sparta, who urges caution, tact, and discipline. Sparta peddles a rumor that Athens is cursed by the goddess (thus subtly implicating Pericles as accursed). Athens, under Pericles, rejects offers to allow the Hellenes to remain free.
431 BC: War begins. Thebes attacks and defeats Plataea, with Athenian help for Plataea arriving too late. Sparta invades Attica. Athens sends a fleet to attack the Pelopponesus and draw troops off their country farms. Pericles delivers his famous “Funeral Oration Speech” in Winter 431 BC.
430 BC: Again Sparta invades Athens and shortly thereafter a great plague falls upon the land “a pestilence of such extent and mortality was nowhere remembered.” It began perhaps in Egypt or Ethiopia and infected Athens through the Piraeus. A rumor spreads that Sparta poisons the water of Athens. The plague brings lawlessness and mass death.
Pericles “The First Citizen” of Athens delivers a more tempered speech in Summer defending himself and wishing the Athenians had heeded all of his advice and not capitulated in any way to Sparta.
Athens conquers Potidaea. Sparta attacks Plataea.
428 BC: Sparta invades Athens again, Lesbos revolts from Athens. Mytilene turns to Sparta for help but Athens votes to spare Mytilene against the advice of Cleon a zealot and war hawk.
425 BC: The Athenians outmaneuver the Spartans at Pylos under the generalship of Demosthenes (not be confused with the great Athenian orator).
422 BC: War hawks Cleon (Athens) and Brasidas (Sparta) battle to the death at the Athenian colony of Amphipolis.
421 BC: After the deaths of Cleon and Brasidas, the moderate Athenian leader Nicias is able to negotiate a peace – the Peace of Nicias which lasted six years.
415 BC: The ill-fated Sicilian Expedition is undertaken initially by Alcibiades who takes up the expansionist agenda from Pericles and Cleon, but the expedition ends in 413 BC in spectacular failure. Both leaders Nicias and Demosthenes are executed in the surrender at Syracuse.
413 BC: In order to escape punishment in Athens, Alcibiades defects to Sparta and advises them on how to attack Athens. From here, Athens was beset by revolts, both internal and external by allies, as well as a troubling alliance between Persia and Sparta.
407 BC: Alcibiades returns to Athens only to be exiled once again over questions of his loyalty.
404 BC: Athens finally surrenders to Spartan general Lysander who defeated the Athenian navy and claimed the Dardanelles, a chief source of Athenian grain. Amidst death and starvation Athens surrenders. Sparta welcomes Athens into its network of allies but destroys Athens’s wall, navy, and riches.
For this reading I used the impeccable Landmark edition of Thucydides’s History of the Peloponnesian War by businessman-turned classical scholar Robert B. Strassler.