Also, part of Lee's planning for the campaign was for a confederate force of troops from North and South Carolina to take up a position around Culpeper, Virginia, forcing Meade to detach troops to guard against a threat to Washington. That part didn't happen, but Lee was unaware of it because the courier carrying the message to him telling him about it was captured in Greencastle by Ulric Dahlgren. So Lee went to Gettysburg and into July 3 believing that a significant part of the Army of the Potomac wasn't there. We know today they were there, but Lee didn't know that, and neither did Longstreet. Lee didn't find out about the missing dispatches until he read about it in the New York Times on July 8.