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. The loftiness of its ideals, its painstaking research, and its beauty of expression have made the History of the Peloponnesian War a work that is in the author's own words, "a possession for all time."