For generations of military historians, the Emmitsburg Road, the highway that runs from Emmitsburg in Maryland into southern Pennsylvania—and that, over the course of a single mile, bisects the Gettysburg battlefield—has served as a kind of festering gash in America’s historiographic landscape. The road’s importance is at the heart of Lee’s attack plan on the battle’s second day, when he directed Longstreet to use it as the geographic centerpiece of his assault. Longstreet, Lee said, was to attack “up the Emmitsburg Road.” The problem is that while Lee had an apparently clear vision of what he meant, at least some of his subordinates, and generations of historians, did not.