Ironically, since Longstreet is marching to Hagerstown, and scouts have pushed up into Pennsylvania, Union observers and generals assume that Lee is invading Pennsylvania; since Jackson has crossed the Potomac to go get Harper’s Ferry, others assume that he is retreating. McClellan assumes this. He writes to his wife, "From all I can gather, secesh is skedaddelling & I don’t think I can catch him unless he is really moving into Penna [....] I begin to think that he is making off to get out of the scrape by recrossing the river at Williamsport." Confusion begins to rule the Federal communications, since it surely is impossible that Lee is both "skedaddling" and invading Pennsylvania both. But that is precisely where his troops are heading. A puzzled and frustrated Gen. Burnside, commanding McClellan’s Right Wing, telegrams "I can hardly understand how they can be moving on these two latter roads at the same time. If they are going into Pennsylvania they would hardly be moving upon the Harper’s Ferry road, and if they are going to recross, how could they he moving upon Gettysburg!"
Pres. Lincoln, even more frustrated, telegrams Gen. McClellan, "Receiving nothing from Harper's Ferry or Martinsburg to-day, and positive information from Wheeling that the line is cut, corroborates the idea that the enemy is recrossing the Potomac. Please do not let him get off without being hurt."
—George Michael Neese, of the Confederate artillery, is on the march in Maryland, and finds the inconvenience of traveling so quickly as to outmarch the commisary wagons and their rations, and so they forage in the surrounding farms:
—Frankfort, Kentucky, the state capital, is occupied by Confederate troops and Gen. Edmund Kirby-Smith.