When Lee and the Army of Northern Virginia marched northwest to the Shenandoah Valley in June 1863, how strong (how many men, cannons, etc.) was the force they left opposing the Army of the Potomac across the Rappahannock? Were there any significant additional layers of defense between Fredericksburg and Richmond?
The Wikipedia article on the Gettsyburg campaign indicates that Lee left "A.P. Hill's Corps in fortifications above Fredericksburg to cover the departure of the army, protect Richmond from any Union incursion across the Rappahannock, and pursue the enemy if Hill thought it advantageous." However, General Hill and Third Corps apparently followed the rest of the Army of Northern Virginia to Pennsylvania on June 15th, and obviously participated in the battle of Gettysburg in July, so most of Hill's troops couldn't have been near Fredericksburg at that time.
I've done a lot of Googling, but haven't found a good source indicating how many men (presumably from the Third Corps) were left behind to hold the line at the Rappahannock.