New York acted promptly, and on the 15th two brigades arrived in Philadelphia on their way to the front.
On the same day Longstreet, having been relieved by Hill, left Culpeper with his corps and marched directly across the country east of the Blue Ridge to occupy Ashby's and Snicker's Gaps.
Stuart's cavalry were to guard his right flank, but did not leave until the next day.

The object of Longstreet's movement was to tempt Hooker to abandon his strong position in front of Washington and march against the Gaps, in which case it was hoped some opportunity might occur by which the rebels could either crush the Army of the Potomac in the open country or possibly outmanoeuvre it, so as to intervene between it and Washington; but Hooker remained stationary.
Rodes' division of Ewell's corps reached Williamsport and remained there during the 16th, 17th, and 18th, to support Jenkins, and receive, and transmit to the rear, the cattle, horses, negroes, and provisions, taken by him.
The commotion created by the approach of the invader was not all one-sided.

General Dix, who commanded at Fortress Monroe, received orders to advance on Richmond, which was weakly defended at this time.

As through their manifold offences in the way of starving our prisoners, etc., the rebel President and his cabinet were afraid of reprisals, there was great dismay at the weakness of the garrison there, and bitter denunciations of Lee for leaving so small a force behind.

The Union troops for this counter-invasion were landed at Yorktown and sent on to the White House.