(1) the direction of Harpers Ferry from Frederick vs the direction to Hagerstown; (2) The road net between Frederick and the Potomac; (3) Lee's line of communication to Winchester and the obvious way Mac might intercept it.
Map created for the Author byKenneth M. Reidclick to enlarge
About the author: Joe Ryan is a Los Angeles trial lawyer who has traveled the route of the Army of Northern Virginia, from Richmond to Gettysburg several times.