from our front during the night, and our march continued to within a few miles of Salem, to bivouac for the night. Scouting parties were sent to Warrenton, where it was ascertained the enemy had withdrawn his forces to Centreville the day previous. General Fitz. Lee's brigade, having encamped near Piedmont, moved on the morning of the 17th (Wednesday), by my direction, toward Aldie, via Middleburg, with the view, if possible, to hold the gap in Bull Run Mountain as a screen to Longstreet's movements. W. H. F. Lee's brigade was kept near the plains, reconnoitering to Thoroughfare Gap, while Robertson's brigade was halted near Rectortown, to move to the support of either. I accompanied Fitz. Lee's brigade as far as Middleburg, where I remained to close up the command, and keep in more ready communication with the rear. The brigade, moving to Aldie, being much worn and the horses having had very little food, was halted by its commander near Dover, to close up, and pickets sent forward to the Aldie gap. These pickets were soon attacked by the enemy's cavalry, advancing from the direction of Fairfax, and were driven back on the main body, which took a position just west of Aldie, on a hill commanding the Snickersville road, but which was liable to be turned by the road to Middleburg. Simultaneously with this attack, I was informed that a large force of the enemy's cavalry was advancing on Middleburg from the direction of Hopewell. Having only a few pickets and my staff here, I sent orders to Munford to look out for the road ton Middleburlg, as by the time my dispatch reached him the enemy would be line the place, and retiring myself toward Rector's Cross-Roads, I sent orders for Robertson to march without delay for Middleburlg, and Chambliss to take the Salem road to the same place. At Aldie ensued one of the most sanguinary cavalry battles of the war, and at the same time most creditable to our arms and glorious to the veteran brigade of Brigadier General Fitz. Lee. They fought most successfully, punishing the enemy with great severity, and maintaining their position till the dispatch received from me made it necessary to move farther back, on account of the threatening attitude of the force at Middleburg. This brigade captured 134 prisoners, among whom were a colonel and captain, several stand of colors, together with horses, arms, and equipments. A large number of the enemy's dead, including a colonel, were left on the field. Brigadier-General Robertson arrived at Middle burg just at dark. I order him to attack the enemy at once, and, with his two regiments, he drove him handsomely out of the place, and pursued him miles on the Hopewell road, the force appearing to scatter. He captured a standard and 70 prisoners. Chambliss' brigade, approaching from that direction caught that night and early next morning 160 and several guidons, the colonel and a small detachment only escaping. It was the First Rhode Island Cavalry. Horses, arms and equipments were captured in proportion. Among the captured were included a number of officers. Our own loss in Robertson's brigade was slight, excepting Major [James H.] McNeil, Sixty-third [Fifth] North Carolina Cavalry, whose wound deprived us of the services of a most valuable officer, and Lieutenant-Colonel [Edward] Cantwell, Fifty-ninth North Carolina troops [Fourth North Carolina Cavalry], captured.