Thucydides

Of all the classical historians to me Thucydides seems to be the one  with the greatest claim to legitimacy. This is not a statement of fact or  even one that I have much confidence but nevertheless (and considering  my somewhat limited reading which includes Herodotus but not Polybius,  Josephus,Tacticus or dozens of others I am doubtlessly unaware of) from  what little I have read of the history of the Peloponesian war it is  immediately obvious that, while taking liberties that contemporary  historians would consider unacceptable (the most well known of which is  his fabrication of speeches based upon what should have been  said), he endeavoures not to tell a story of what happened or perpetuate a  popular myth extolling one side or one set of values but to find the  real causes of events. While the scope of the Histories makes it (perhaps) more valuable as a source for contemporary historians  the History of the Peloponesian War in itself goes a long way to explain why two nations, one an insular land based power and the other a commerce orientated maritime one, would have such an overlap of interests so soon after the persion wars.