William Swinton, Campaigns of the Army of the Potomac

Buford's division of troopers had crossed the Rapidan at Germanna Ford on the night of the 10th, after the Confederates had begun their movement, but was met on the morning of the 11th by Fitz Hugh Lee's horsemen; whereupon Buford, falling back over the Rapidan, united at Brandy Station with Pleasonton's main body of cavalry, and then followed the army across the Rappahannock.

On the following morning, Monday, October 12th, Lee advanced from Culpepper; but finding that Meade had been too quick for him, and that his first turning movement had failed, owing to the rapid retreat of his opponent, he determined, instead of following up Meade by the direct line of his retreat, to make a new flank movement by routes to the west, ‘with the design,’ as he says in his report, ‘of reaching the Orange and Alexandria railroad north of the Rappahannock, and interrupting the retreat of the enemy.’ This operation had very near been successful, owing to the uncertainty of General Meade as to his antagonist's real purpose, and the false movements resulting therefrom.

Having put the Rappahannock between himself and Lee, Meade conceived that his retreat might have been premature, especially as he became aware on the morning of the 12th that Lee had halted at Culpepper, and it was uncertain whether he intended to do more. Accordingly, that afternoon the main body of the army, consisting of the Second, Fifth, and Sixth corps, with Buford's cavalry division, was countermarched to the south bank of the Rappahannock to proceed back towards Culpepper. General Meade designed to give battle if Lee was really there. But, as has been seen, the latter had that morning left Culpepper to plant himself by a circuitous turning movement on Meade's line of retreat towards Washington. Thus was presented the curious contretemps, that while on the 12th the main body of the army was marching southward to meet Lee at Culpepper, Lee was moving rapidly northward on parallel roads to lay hold of Meade's communications