Possible Clues:

• Chronicler of the Greco-Persian Wars
• Greek historian from the 5th century BC
• In the historical sense, old Greek child-killer to return from America
• Point grasped by star American historian
• Historian reveals bad king to us in a different way
• Greek 'Father of History'
• Greek "Father of History"
• Historian found point dividing Churchill, say, and America