Peloponnesian War

The Peloponnesian War (431–404 BC) was an Ancient Greek military conflict, fought by Athens and its allies, against the Peloponnesian League, led by Sparta. Athens was the greatest sea power, and Sparta the greatest land power in 5th century BC Greece.

In the first phase, the Archidamian War, Sparta launched repeated invasions of Attica, while Athens took advantage of its naval supremacy to raid the coast of the Peloponnese.

This period of the war ended in 421 BC, with the signing of the Peace of Nicias. That treaty was soon undermined by renewed fighting in the Peloponnese. In 415 BC Athens dispatched a large force, led by Alcibiades, to attack Syracuse in Sicily. The attack failed, with the destruction of the entire force, in 413 BC. This made Athens vulnerable.

The final phase of the war is called the Decelean War, or the Peloponnesian War. In this phase, Sparta, now receiving support from the Achaemenid Empire, supported rebellions in Athens' subject states in the Aegean Sea and Ionia, undermining Athens' empire. Eventually, Athens lost its naval supremacy. The destruction of the Athenian fleet in a battle in 405 BC effectively ended the war, and Athens surrendered in the following year.