These two brigades, with Imboden's brigade, and White's battalion, made quite a large cavalry force: Imboden, however, was also detached to break up the Baltimore and Ohio Railroad to prevent forces from the West from taking Lee in rear; all of which goes to show how sensitive the Confederate commander was in regard to any danger threatening his communications with Richmond.
At 1 A.M.on the 25th, Stuart started on his expedition and advanced to Haymarket, where he unexpectedly came upon Hancock's corps, which had left Thoroughfare Gap, and was on its way to Gum Springs.
He opened fire against them but was soon driven off.

He then returned to Buckland and Gainesville; for to keep on, in presence of our troops, would have frustrated the object of his expedition by indicating its purpose.
This was the day in which Longstreet and Hill united their columns at Hagerstown.

Some Union spies who counted the rebel forces as they passed through the town made their number to be 91,000 infantry, 280 guns and 1,100 cavalry.

This statement, though much exaggerated, gained great credence at the time, and added to the excitement among the loyal people throughout the Northern States, while the copperhead element were proportionally active and jubilant.
On the 26th, General French assumed command of the garrison at Harper's Ferry, then posted at Maryland Heights.
On the same day the Richmond Government were much alarmed by the unexpected appearance of Colonel Spear's 11th Pennsylvania Cavalry within eleven miles of the city.

Spear had made quite a successful and very destructive raid on the railroads and other lines of communication.