Such was the posture of affairs when General Hooker’s chief-of-staff became so much puzzled, and described the Federal army as “boggling around,” and not knowing “what they were going after.”  Lee’s whole movement, it appears, was regarded as a feint to “cover a cavalry-raid on the south side of the river”—­a strange conclusion, it would seem, in reference to a movement of such magnitude.  It now became absolutely necessary that Lee’s designs should be unmasked, if possible; and to effect this object Stuart’s cavalry force, covering the southern flank, east of the Blue Ridge, must be driven back.  This was undertaken in a deliberate manner.  Three corps of cavalry, with a division of infantry and a full supply of artillery, were sent forward from the vicinity of Manassas, to drive Stuart in on all the roads leading to the mountain.  A fierce struggle followed, in which Stuart, who knew the importance of his position, fought the great force opposed to him from every hill and knoll.  But he was forced back steadily, in spite of a determined resistance, and at Upperville a hand-to-hand sabre-fight wound up the movement, in which the Federal cavalry was checked, when Stuart fell back toward Paris, crowned the mountain-side with his cannon, and awaited a final attack.  This was not, however, made.  Night approaching, the Federal force fell back toward Manassas, and on the next morning Stuart followed them, on the same road over which he had so rapidly retreated, beyond Middleburg.

Lee paid little attention to these operations on his flank east of the mountains, but proceeded steadily, in personal command of his infantry, in the direction of the Cumberland Valley.  Ewell was moving rapidly toward Harrisburg, with orders to “take” that place “if he deemed his force adequate,"[1] General Jenkins, commanding cavalry, preceding the advance of his infantry.  He had thus pierced the enemy’s territory, and it was necessary promptly to support him.  Hill and Longstreet were accordingly directed to pass the Potomac at Shepherdstown and Williamsport.  The columns united at Hagerstown, and on the 27th of June entered Chambersburg.

[Footnote 1:  This statement of Lee’s orders is derived by the writer from Lieutenant-General Ewell.]

General Hooker had followed, crossing the Potomac, opposite Leesburg, at about the moment when Lee’s rear was passing from Maryland into Pennsylvania.  The direction of the Federal march was toward Frederick, from which point General Hooker could move in either one of two directions—­either across the mountain toward Boonsboro, which would throw him upon Lee’s communications, or northward to Westminster, or Gettysburg, which would lead to an open collision with the invading army in a pitched battle.