The discussion got me to thinking so I looked up some old (ancient) notes of mine from college. The class was on historiography and we read several books on the subject, but my notes have this to say about the art of writing history:
The two primary decisions a historian makes in writing his books or monograph are:
PURPOSE: What is the book supposed to do? Here is the list of possible purposes given:
1. To describe a new or relatively undeveloped area of history
2. to present new research
3. to present new analysis or conclusions
4. to present new aspects of an already covered era or event
5. to provide a coherent narrative of an event previously not covered
in such a fashion
6. to provide the history to a new audience
7. to persuade an audience of some conclusion, new or old
8. To simply entertain.
While these goals are not mutually exclusive, having more than two or three for one book is very ambitious.
The audiences can be varied too:
1. Scholars in a particular field of study
2. Academia, either a particular discipline or in general
3. An unrelated field in an effort to establish some cross-fertilization.
4. All interested groups or parties in a society or field of interest-
5. The general public
Again, it is very difficult to write a book with more than one audience in mind. Different audiences demand different things from a work of history.
This last point is very important. When wargamers started reading and researching history, they started asking different questions and demanding far different kinds of history and books from authors than other audiences. (Don't blame Petre for that.) It created "new histories" and new research, not because the information hadn't been available before, but because the questions hadn't been asked before. You see that in just the discussions of just maps.