An eyewitness historian offers a chronological account of the prolonged conflict between Athens and Sparta, blending detailed narratives of land and naval campaigns with close analysis of political decisions. The work traces the war's origins and major operations, records public debates and formal speeches as reported by the historian, and examines social consequences such as disease, sieges, and internal strife. Attention centers on strategy, shifting alliances, and the practical effects of power struggles, while periodic methodological remarks address sources and chronology and the overall aim is to explain causes and outcomes rather than to deliver moral judgments.