...the rebels were concentrating a large force at a point on the Fairfax Court-House road, about two miles from Centreville, their principal object evidently being to cut off one of our was on trains. -- Gen. Reno had previously been sent down the road. Gen. Pope ordered Gen. Heintzelman's command to proceed at once to the locality designated, with the object, if practicable, of dislodging them. This force...