The Peloponnesian War (431-404 B.C.E.) was the greatest disturbance in Greek history to that time. The bitter rivalry between the two chief city-states, Athens and Sparta, and their respective allies ended with the ruin of Athens naval hegemony and what the Greek historian Thucydides (ca. 460-400 B.C.E.) called a convulsion affecting all humankind. With the detachment of a clinician and the dramatic skill of a poet, Thucydides recreates the often savage events of the war and brings to life its chief protagonists: Pericles, Nicias, Cleon, Alcibiades, and others. The first of the scientific historians, Thucydides makes use of documentary material and relies on eyewitness accounts; even where direct documentary evidence is lacking, his keen understanding of human nature helps him to uncover the truth of what actually happened.