While Lee’s invasion of the north was designed to solve a short-term problem (starvation), his overarching goal was to win the war. I would suggest that a simple examination of the map would show that he was being overly ambitious. His first real military objective was Harrisburg, the Pennsylvania State Capitol. But that is nearly 100 miles from the point at which he crossed the Potomac. There are existing documents showing that he was concerned about the length of his supply lines. Even Gettysburg is 60 miles north of Virginia. It is understandable that he would have thought that both Baltimore and WASHDC were too heavily defended for him to chance a direct attack. Why then was Harrisburg so high on his list? It was much more of a political objective than a military one. Carlisle, with its vast military cache was a much more attractive target, but would not have grabbed the headlines that Harrisburg would have. In Section 21, I suggest alternative routes that may have been more inviting and with a much shorter supply link back to Virginia. Was it not folly that he thought that he could sustain an army of 100K men 100 miles or more into enemy territory?
As far as the Army of the Potomac (AoP), they had the huge advantage of rail links as far as Harrisburg with Hanover and Westminster as interim stops. Lee had wagons and hundreds of horses and mules to feed! At ‘only’ a hundred miles, Harrisburg could have been reached in about a week of intensive marching. A rest stop at Carlisle would likely have been necessary. But LTG Ewell took his time getting there, allowing his men to ‘fatten’ themselves on the bounty of Maryland and Pennsylvania.
True history seems to suggest that Lee was quite surprised to learn (o/a 26 June) that Hooker had moved his army so quickly in pursuit of the Army of Northern Virginia; that they were at Frederick and pressing in on Emmittsburg. He was forced to abandon all plans of attack farther north and to consolidate his army near Gettysburg. Again, that city was only chosen because it had so many roads allowing his various forces to avoid major congestion.
I’d even go so far as to suggest that if Lee indeed intended to move on Philadelphia [1], he could have gotten there via York rather than Harrisburg. This would have allowed him to use Gettysburg as a supply point, much as the AoP did at Westminster. As I suggest above in Section 22d, with Ewell occupying Gettysburg, Buford’s insolent ambush scheme would never have been considered. Even as the AoP pressed in from the south, he could have plundered Carlisle and the surrounding farmlands to amass a huge cache of supplies. Granted the ‘castle walls’ of Gettysburg were not as favorably aligned to defend against an attack from the south, but all things considered, it was relatively easy to defend. Although we have no details, there is mention that Lee had scoped out a defensive position near Cashtown should he need to make a stand.
Every military commander who was onsite seemed to agree that the actual town of Gettysburg had no strategic nor tactical value. Yet, it would seem that Lee could have turned it into his own mini-Westminster by using the road network to gather supplies. With Gettysburg firmly in his control, Lee had the options of continuing to push east or to turn south to more directly confront the AoP.
Why did Lee feel that he had to plunge 100 miles into the northern countryside, when Gettysburg –York were there for the taking?
[1] A fact disputed by some historians.