Interesting read. Mosby caused all sorts of head aches for the Union in the Shenandoah during the war.
If Custer had actually won the Battle of the Little Big Horn (thought it would be a killing and capture of old men, women, and children like the snowy massacre he conducted at the Washita River) he was slated to return east by train to be nominated by acclamation for president at the about to begin Democrat convention. The party bigwigs in New York had things lined up for him.
Mosby's Confederacy was east of the Blue Ridge, in an area comprising much of upper Fauquier County, east toward Fairfax, and parts of Loudoun County. The person who annoyed the Yankees in the Shenandoah Valley was one of the South's other romantic cav commanders, General Turner Ashby. Ashby was a rock star early in the War but is less well remembered by the general public since he was killed in '62, and so much happened after that, while Mosby, of course, survived.