The Peloponnesian War Begins (431 BCE)

Event Summary:
In 431 BCE, a protracted and destructive war broke out between Athens and Sparta. The conflict reshaped Greek politics and marked the decline of the classical era.

Delian League Expands Athenian Power:
Athens led a naval alliance initially formed to defend against Persia. Over time, it transformed the Delian League into an Athenian empire, extracting tribute and imposing garrisons.

Sparta Fears Growing Influence:
Sparta and its allies, the Peloponnesian League, viewed Athens’ rising naval and economic power as destabilizing. Tensions over trade routes, colonial interference, and shifting alliances led to war.

Pericles Prepares Athens:
Athenian leader Pericles (age 40s) implemented a defensive strategy. He fortified the city, avoided land battles, and relied on naval superiority. He brought rural populations inside city walls for safety.

Sparta Invades Attica Repeatedly:
Each year, Spartan hoplites marched into Athenian territory and destroyed crops. Athens countered with naval raids and economic pressure on Peloponnesian ports.

Plague Devastates Athens:
One year later, in 430 BCE, disease swept through overcrowded Athens. The plague killed a third of the population, including Pericles (age 49) in 429 BCE, leaving leadership fragmented.

War Drags On for Decades:
Neither side could force a decisive victory. Battles spread across Greece, Sicily, and the Aegean, draining both alliances.

Sicilian Expedition Fails Catastrophically:
In 415 BCE, Athens attempted to conquer Sicily. Miscommunication, rivalries, and poor planning led to the destruction of the Athenian fleet and tens of thousands of soldiers by 413 BCE.

Internal Strife Erupts in Athens:
Political turmoil rocked the city. Oligarchs briefly seized control. Democratic ideals came under intense strain.

Sparta Gains Persian Support:
Sparta negotiated with Persia for naval funding. With a new fleet and Persian gold, Sparta challenged Athens at sea.

Athens Surrenders in 404 BCE:
After years of blockade and starvation, Athens surrendered. Sparta imposed an oligarchic regime, the Thirty Tyrants, ending Athenian democracy.

Greek Unity Shattered:
The war devastated city-states. Economic ruin and distrust flourished. Persian influence resurged in Greek affairs.

Why It Matters:
The Peloponnesian War ended Athens’ golden age and weakened Greek independence. It laid the groundwork for Macedon’s rise under Philip II and Alexander the Great.