The map - what is it doing there?

Nothing dresses up a Civil War book like a gorgeous map or two but I often ask myself, what is it doing there? Is it functioning as a sketch, a diagram, or a true statement of dispositions, times, and routes?

A sketch - a rough visual display of information to help the reader locate the narrative in a spatial framework.

A diagram - an abstract statement of relative positions at relative times conveying an abstract sense of progress made over time.

A true statement - an accurate record of location, frontage, and movement across a map accurately representing roads, woodlines, streams as of that date.

The more detailed the map, the more uneasy I become. The responsible historian has footnoted in his narrative every odd fact, statement, or quotation needing support, but here I am in front of a visual display of hundreds, even thousands of pieces of information lacking a single note or explanation.

How did we arrive at that depiction of Cheatham's front line as of 2:00 pm?

As the editor of an ACW battle book, I would not have the guts to venture beyond diagram, as defined above. If I ran maps, I would run disclaimers where I decided the limits of information were.

On the other hand, a painstaking mapmaker could write quite an interesting book entirely about his maps and how they came together. Why hasn't that ben done?