The development of Greek and Roman historiography is difficult to describe. So many ancient histories are lost and those that survive are hardly representative. In this thesis I argue that despite these difficulties some historiographical trends remain discernible, and examine three such fundamental changes to the ancient historian’s craft.

First, I trace a change in the historian’s rhetoric of truthfulness. From the first century BC onwards, historians invoked their lack of partiality in their pursuit of their readers’ trust. By contrast, the historians of the fifth and fourth centuries BC highlighted not the absence of any biases but their authorial accuracy. Second, I examine the way in which the ‘rise and fall’ pattern, found in different forms across Classical Greek historiography, no longer easily applies to the state of Rome. In the histories of Rome, at least from the first century AD, greatness remains dangerous for individuals but no longer for the state. Conceptions of Rome’s eternity open up new historiographical possibilities. Third, I argue that comparisons become common in the histories of the Late Roman Republic and Principate. Individuals and events are described as reincarnations of previous ones. Such explicit typologies are rarely found in Classical Greek histories.

These historiographical changes call for explanations. The textual and genre-specific approach to ancient historiography, which studies ancient histories with little regard to events outside of the narratives, offers no help. I turn to major historical events, long-term cultural changes, new intellectual movements, and changes specific to the ancient historians and their position within society, to explain the changes to historical narratives identified above. I aim to demonstrate that, and describe in detail how, the concerns and shape of ancient historiography are determined by history.