into Maryland, joining our army north of the Potomac. The Commanding General wrote me authorizing this move if I deemed it practicable."
Now, at the time of this correspondence, Ewell's corps, whose right flank Stuart was "to guard," was just beginning its march northward from Hagerstown, and General Hooker's army was in Virginia. General Stuart's plan, then, contemplated passing round General Hooker's rear, while his army was still south of the Potomac; and General Lee's authorisation contemplated that, and that only. It did not authorize Stuart to carry out his plan of passing round the enemy's rear after the enemy had transferred his army to the north side of the Potomac. Colonel Mos-by confirms this view, for he says: (p. 212), "The orders contemplated Stuart's crossing the Potomac in advance of both armies."
And General Stuart's plan, proposed to General Lee, and to which he understood General Lee agreed, was, to use the words of his report, "to cross into Maryland, joining our army north of the Potomac." He gives no intimation that he understood that he was to join Ewell "on the Susquehanna," as Colonel Mos-by states the case. General Stuart also tells us that General Lee "directed me, after crossing, to proceed with all dispatch to join the right of the army in Pennsylvania."
Colonel Mosby himself says: "The object was to go the most direct route to Ewell." (P. 212.);
Precisely here was the error of judgment committed by the gallant Stuart he did not keep in view the main object of his expedition, which was to co-operate with Ewell in his march from the Maryland line to Harrisburg. This, the first and principal duty imposed upon the Chief of Cavalry by the Commanding General, was subordinated to the secondary and incidental object of damaging General Hooker's communications and making a raid around his army.
When General Stuart discovered that the Federal army was moving to cross the Potomac, which it did three days before he crossed at Seneca Ford, two things should have been considered by him, first, that the reason given by General Longstreet for the suggestion that he should pass in rear of the Federal army (viz., that his passage of the Potomac by Shepherdstown "would
