"The History of the Peloponnesian War" by Thucydides is a historical account written between 431-411 BC. It chronicles the devastating conflict between Sparta's Peloponnesian League and Athens' Delian League. Written by an Athenian general who fought in the war, this unfinished work ends abruptly mid-sentence. Considered one of the earliest scholarly histories, it employs strict chronology and extensive speeches while attempting objectivity. Thucydides attributes events to human choices rather than divine intervention, establishing methods that shaped Western historical writing.