History of the Peloponnesian War
One of Thucydides' major innovations was to use a strict standard of chronology, recording events by year, each year consisting of the summer campaigning season and a less active winter season. As a result, events that span several years are divided up and described in parts of the book that are sometimes quite distant from one another, causing the impression that he is oscillating between the various theatres of conflict. This method contrasts sharply with Herodotus' earlier work The Histories, which jumps around chronologically.