Jackson’s arrangements for deceiving his enemy, for concealing his line of retreat, and for drawing Pope northward on Centreville, had been carefully thought out.  The march from Manassas was no hasty movement to the rear.  Taliaferro, as soon as darkness fell, had moved by New Market on Bald Hill.  At 1 A.M.  Ewell followed Hill to Blackburn’s Ford; but instead of continuing the march on Centrevile, had crossed Bull Run, and moving up stream, had joined Taliaferro by way of the Stone Bridge.  Hill, leaving Centreville at 10 A.M., marched to the same rendezvous.  Thus, while the attention of the enemy was attracted to Centreville, Jackson’s divisions were concentrated in the woods beyond Bull Bun, some five or six miles west.  The position in which his troops were resting had been skilfully selected.  South of Sudley Springs, and north of the Warrenton turnpike, it was within twelve miles of Thoroughfare Gap, and a line of retreat, in case of emergency, as well as a line by which Lee could join him, should Thoroughfare Gap be blocked, ran to Aldie Gap, the northern pass of the Bull Run Mountains.  Established on his enemy’s flank, he could avoid the full shock of his force should Lee be delayed, or he could strike effectively himself; and it was to retain the power of striking that he had not moved further northward, and secured his front by camping beyond Catharpen Run.  It was essential that he should be prepared for offensive action.  The object with which he had marched upon Manassas had only been half accomplished.  Pope had been compelled to abandon the strong line of the Rappahannock, but he had not yet been defeated; and if he were not defeated, he would combine with McClellan, and advance in a few days in overwhelming force.  Lee looked for a battle with Pope before he could be reinforced, and to achieve this end it was necessary that the Federal commander should be prevented from retreating further; that Jackson should hold him by the throat until Lee should come up to administer the coup de grace.

It was with this purpose in his mind that Jackson had taken post near Groveton, and he was now awaiting the information that should tell him the time had come to strike.  But, as already related, the march of the Federals on Manassas was slow and toilsome.  It was not till the morning was well on that the brigade of Taliaferro’s division near Groveton, commanded by Colonel Bradley Johnson, was warned by the cavalry that the enemy was moving through Gainesville in great strength.  A skirmish took place a mile or two north of that village, and Johnson, finding himself menaced by far superior numbers, fell back to the wood near the Douglass House.  He was not followed.  The Union generals, Sigel and Reynolds, who had been ordered to Manassas to “bag” Jackson, had received no word of his departure from the Junction; and believing that Johnson’s small force was composed only of cavalry, they resumed the march which had been temporarily interrupted.