History of the Peloponnesian War

A pro-democracy faction in Amphipolis revolts against its ruling oligarchy. Cleon leads troops in support of the democrats and Brasidas in support of the oligarchs. Thucydides describes Brasidas’ strategy and the battle, which ends with a Peloponnesian victory. Brasidas and Cleon are killed. The people of Amphipolis honor Brasidas for his skill and bravery.

After the battle, both sides want peace. Spartan King Pleistoanax and Nicias of Athens conduct negotiations and establish both a peace treaty and an alliance. Thucydides reproduces the terms and also explains his method for dating events: He measures time according to the seasons and the number of years that have passed since the war’s onset. 

Thucydides explains how he was able to study the period: After the fall of Amphipolis, which he failed to prevent as an Athenian general, he was exiled and thus able to view the war from both sides.

Following the treaty and alliance, Athens and Sparta almost immediately become suspicious of each other. Corinth and other Peloponnesian allies agitate against the peace treaty. Corinth seeks a defensive alliance with Argos, which aspired to assume leadership in the Peloponnese despite being democratic (unlike the mostly oligarchic region).