New "Five books on ..." series

Book recommendations that reasonably cover any Civil War topic, large or small, can be difficult to make when limiting oneself to only five source selections, but I am going to try anyway with a new (hopefully regular) series on the site called "Five books on". The biggest subjects will be avoided in their broadest sense. For example, instead of "Five books on Lincoln" or "Five books on Gettysburg," it might be "Five books on Lincoln's emancipation policy" or "Five books on Little Round Top." These won't all necessarily be great books, either, sometimes just the best available from a limited lot. There will probably be a bias toward the modern literature so some still useful classics will be left out, and I will occasionally cheat a little if a single author wrote an entire series of outstanding related titles that might dominate the short list. So, let's get started with ...