As to Gettysburg, an excellent read is “Retreat from Gettysburg”
Lee actually did an excellent job of moving his forces from that battlefield back to Virginia. There was a lot of Cavalry action including Custer attacking and harassing the supply trains and forces heading south. Despite the pressure, Lee was able to get the majority of the supplies his forces collected back to Virginia.
Yeah but the South was pretty much doomed right then and there. The main reason he was in the North was to take from the fat of the land for his Army and to take a northern Capitol. Virginia was lean and pretty picked clean and by returning he was leading his men and horses right back into starvation
