MARCH 12-14, 1865.-Scout in Loudoun County, Va.

Report of Colonel Nelson B. Sweitzer, Sixteenth New York Cavalry.

HEADQUARTERS SIXTEENTH NEW YORK CAVALRY, Vienna, Va., March 16, 1865.

CAPTAIN: I have the honor to report that, in obedience to instructions from brigade headquarters March 10, 1865, I proceeded on the morning of the 12th instant, with 2 staff and 10 line officers and 357 enlisted men, with three days' rations; 6 officers and 157 enlisted men absent under Captain J. Schneider; left 142 dismounted men in camp and 4 officers, 2 on the sick report; the 142 dismounted men included sick men and men permanently disabled unavailable for efficient mounted duty. Proceeding by the way of Dranesville and Farmwell I reached the vicinity of Leesburg the morning of the 13th. All along the route the reports were that quite a force of White's and Mosby's men were in and about Leesburg.

Making a hasty reconnaissance of Leesburg before entering with the whole command, I found no force there; that White and Mosby had left, White for the Valley of the Shenandoah and Mosby for the country about Vienna, &c. Small parties were seen about Leesburg, but would scatter to the woods when pursued. Thinking I might come upon some of the parties in the direction of Hamilton and Waterford I pushed on, with an extended line of skirmishers and patrols, but found nothing there but small parties ranging from four to fifteen, who kept out of range. Ascertained that no organized force of the rebels was in the country, and that the report of large force was for the purpose of covering the conscripting and impressing going on in Loudoun County and to draw our forces from the lower country to assist marauding parties during their absence.

Moving back to the vicinity of Ball's Mills and Goose Creek, hoping to come upon some of the parties at the fords, on the 14th I returned by the way of Gum Springs and Flint Hill to this post. From the opportunities of perfect information it is difficult to capture these guerrillas except by detachments operating in concert and rapidly, with information as to the locality of the rebels. The force of Mosby and White have been scattered about the county of Loudoun, conscripting and impressing horses and provisions, and between which two parties there is great hostility, from their stealing each other's horses, &c. This conscripting, &c., is growing very unpopular, and I anticipate good results to the Union cause, as it leads to the public moving in self-defense and anxious to assist the Union forces, in which they now do but little. In coming back I endeavored by halting and stationing parties to catch any small parties following my rear, to pick up stragglers, but the enemy was unusually wary. I had one man and one horse wounded during the scout, which comprised all the casualties.

My original plan was to have scouted the country to the Shenandoah at Harper's Ferry, obtaining a fresh supply of rations, and return over a route near the base of the mountains, but the information of the guerrillas taking advantage of the absence of cavalry in making forays in the vicinity of the post decided my course as decided above.

I am, very respectfully, your obedient servant,
N. B. SWEITZER,

Colonel Sixteenth New York Cavalry, Commanding Post.

Captain CHARLES I. WICKERSHAM,

Asst. Adjt. General, First Separate Brigadier, Fairfax Court-House, Va.