Colonel Mosby here admits that Stuart was to cross the Potomac with three brigades, "in advance of the enemy and move into Pennsylvania with Ewell," and not, as he has heretofore insisted, "to move into Pennsylvania and join Ewell on the Susquehanna,"
What Stuart understood to be his instructions with reference to the two brigades left in Virginia can best be seen by referring to the orders he transmitted to the commanding officer of these brigades, which were as follows: "Your object will be to watch the enemy; deceive him as to our designs, and harass his rear if you find him retiring. Be always on the alert; let nothing escape your observation, and miss no opportunity to damage the enemy. After the enemy has moved beyond your reach, leave pickets in the mountain gaps, withdraw to the west side of the Shenandoah, cross the Potomac and follow the army, keeping on its right and rear."
Stuart himself says that General Lee directed him, "after crossing to proceed with all dispatch to join the right of the army in Pennsylvania."
These two statements from General Stuart himself show clearly what he was instructed to do, but did not do with the cavalry, and fully justify General Pee in saying that "it was expected that as soon as the Pederal Army should cross the Potomac General Stuart would give notice of its movements; and nothing having been heard from him since our entrance into Maryland, it was inferred that the enemy had not left Virginia." General Lee had a right to expect that he would be advised as soon as the enemy crossed the Potomac, and that all of Stuart's brigades would then be in the positions assigned them by his orders. Instead of that, Stuart and three of his best brigades were lost for a whole week, and, for all General Lee knew, were captured or destroyed; and the two brigades which should have been on his "right and rear" in Pennsylvania assured him by their absence that the enemy was still in their front, until July 1st, by which time Hill was fighting the head of Meade's Army at Gettysburg.
Colonel Mosby says that General Stuart left two brigades with Lee and Longstreet. and that therefore Lee had all the cavalry
