From Washington

Washingtou, Oct. 21. Accounts frorn the Army of the Potomac yesterday noon, state that Kilpatrick's cavalry pushed back Stuart's rebel caralry beyond Gaiasville, towards Warrenton. There was considerable fighting, but little loss to us. It is positively itated that Lee was at Warrenton on Monday, and had formed a line of battle, wdposted artillery. Our troops were moving steadily onward in columns. Buford reports there was no enemy in force in Thsroughfare Gap, at 10 P. M., jesterday. The rebels were in force at Buekland Mills, four miles from Gaines tille. Our troops are advancing. A gteat battle is considered imminent. Special Dispateh tothe Detroit Free Press. Washington, Oct. 21. Advices from the front are to the following effect : A. large force of Lee's Tmy was belicved to be at'Warrcnton Monday, and had formed in battle array, nd posted their artillery to check the idvaaee of Meade's force. Our troops were moving steadily on, their columns being so disposed as to prevent surprise. Buford's división took the road through Thoroughfare Gap, and found no enemy. In the engagement on Monday Gen. Custer was conspicuous, and reports that the rebel cavalry was driven beyond Backland Mills from Gainesville, where our cavalry encountered rebel infantry nd artillery in line of battle, their line xtending a mile. At one time Davis' brigade of cavalry and artillery were cut off completely. He got well out of difficulty, however. Our loss in killed, Woanded and missing was about 200, and eral wagons, one of which contained the offioial papers of the brigade. At one 'o'clock today several of our corps wero reported to be marching againet the enemy, and a battle was con"idered imminent. Our headquarters were yesterday Drorping in the immediate vicinity of urovctown and Gainesville, which means that our army was theo considerably in dvnce of those places, but last night oeadiparters wore iu an entirely different PttlOD.