I find the Official Military Atlas to be extremely valuable in presenting period maps.
Also, I have obtained 19th Century Map reprints from Jonathan Sheppard Books for a number of states. You might look to their S24, Virginia, with Deleware, Maryland, and West Virginia-1864.
Their notation: "Useful to anyone studying the Civil War and showing the newly created state of West Virginia, this 1864 A. J. Johnson map locates counties, roads, towns and railways in all four states. Rivers and creeks are also identified.
18" X 24", including margins.
This is a somewhat small scale map and will require a magnifying glass for careful study.