Lee won Gettysburg. Then he crushed the Army of the Potomac at Union Mills. Now Lee sits on the doorstep of Washington DC, just three short miles from capturing the Union capital and ending the war.
Fiction (obviously), but very well written and entertaining. The authors William Forstchen and Newt Gingrich (yes, THAT Newt) really do a good job of providing just the right amount of detail. They don't go overboard ala Turtledove, but enough detail is present to understand the motivations of the personalities involved. The book moves along swiftly without getting bogged done in the minutia of battle.
This is book 2 of a trilogy. I haven't read book 1, Gettysburg, but I will remedy that soon enough.