As long as the subject of history is studied, the fame of the Athenian Thucydides will be secure. His stature as an historian has never been surpassed and rarely equaled. In his 'History of the Peloponnesian War', he accomplished what few others have: He wrote an eyewitness account of the events of the war as they unfolded.
Thucydides was born no later than 460 BC. The Peloponnesian War between Athens and Sparta lasted from 431 to 404. Of his life very little is known except what he tells in the book itself. He was in Athens during a serious outbreak of plague in 430 and 429. In 424 he was elected a military magistrate and was given command of a fleet. Because he failed to prevent the capture of the city of Amphipolis by the Spartans, he was recalled, tried, and sentenced to exile. Thus he was away from Athens for most of the rest of the war. For purposes of his history, this exile gave him the chance for travel and wider contacts among the various combatants, especially in Sparta. His exile ended with the defeat of Athens by Sparta in 404. It is presumed that he died about that time because his history is incomplete; it ended in 411 BC.
From the 'History' it is assumed that Thucydides worked in three stages. He made notes of events as they occurred. These he reworked into a consecutive narrative, and finally he elaborated the narrative into the full history. The 'History' treats all aspects of the war: its technical problems, logistics, sieges, and other military features. It is also about the personalities, the political and military leadership, and, significantly, about the behavior of peoples as the long war dragged on.