Thucydides was an Athenian general and historian who lived from around 460 to 400 BCE. After witnessing much of the Peloponnesian War firsthand, he was exiled from Athens in 424 BCE following his failure to prevent the capture of a key city. Despite remaining unfinished at the time of his death, The History of the Peloponnesian War revolutionized the way history was written. Thucydides’ meticulous approach to gathering evidence, interviewing witnesses, and analyzing causes and effects laid the foundation for the scientific method in historical study. His lucid prose and unflinching analysis of human behavior in war and politics left a lasting impact on historians, philosophers, and political thinkers alike, earning him recognition as both the first true historian and a pioneer of political realism.