Culpeper, Monday, August 11.—The brigade of cavalry, under command of Gen. Buford, made a descent on Madison Court House on Tuesday, the 5th inst. He found the Confederates had been there, but had left. He made a reconnoissance In every direction, and met Confederate pickets on every road. On the 7th inst., the pickets on the road to Stannardsville had a skirmish, losing one killed and three wounded. On the 8th, the 1st Maryland had another skirmish on the Orange Court House road, in which they lost, and about a dozen taken prisoners. Being reinforced by the 1st Michigan, the Confederates were driven to the Rapidan. A strong reconnoissance was made the same evening to the Rapidan, on the Orange road, and a skirmish was going on without loss, when orders came from General Buford to return to Madison Court House.—The party got back at 9 a. m. on the 9th, and found everything ready for a retreat towards Sperryville. as the Confederates were approaching from every direction. The party reached Woodville in safety, and there encamped.—They reached Culpeper Monday next.