No. 2. Report of Major Alonzo W. Adams, First New York Cavalry.

HDQRS. FIRST REGIMENT NEW YORK CAVALRY, Camp Kearny, Va., December 2, 1861.

SIR: For the information of the Commanding General I have the honor to report that, in accordance with General Orders, No. 37, and in obedience to instructions from General Franklin, I this day proceeded with a small squadron of cavalry [79 rank and file] up the Little River turnpike to the town of Annandale, and about 1 mile south of the outer line of our pickets. At Annandale I learned that a body of rebel cavalry had been seen yesterday morning in that vicinity. Having an advance and rear guard deployed as flankers and skirmishers, I moved up the turnpike in the direction of Fairfax Court-House about 3 1/2 or 4 miles, without opposition and without discovering the enemy's pickets. I returned to Annandale about 2 o'clock p.m., where I met with Lieutenant-Colonel Pinto, of the Thirty-second New York Regiment, commander of our picket guard, who was accompanied by two officers-lieutenant-and 22 men of the New York Mounted Rifles, by whom I was informed that we were probably surrounded by the enemy, as a battalion of rebel cavalry, more than 200 strong, had, not fifteen minutes before my arrival, dashed through that place, killing one of our pickets and taking with them several more as prisoners. Having thrown out skirmishers and posted vedettes, I disposed my command, including that of the Mounted Rifles, in order of battle, and waited an attack from the enemy.

In the mean time I sent Captain Hendrich, of my squadron, to the lieutenant-colonel of the Forty-fifth Regiment New York Volunteers, who was about half a mile distant, in command of 3 companies of his regiment, with a request that in case of attack, which was momentarily expected, he should support me with his infantry. Captain Hendrich returned with a message from the lieutenant-colonel acceding to my request and promising to move up his command nearer to Annandale. Confidently relying upon this pledge, I held possession of the place until about 5 o'clock p.m., when to my surprise I ascertained that the three companies of the Forty-fifth, instead of coming to my support, had retired in the direction of Falls Church, and probably to their encampment.

About 6 o'clock a messenger whom I had dispatched to General Franklin for orders returned with a message from Brigadier-General Kearny, advising me that General Franklin was in Washington; that I must not attempt to hold Annandale over night, but return with my command to camp; and also that he [General Kearny] had dispatched two squadrons of cavalry to my support. My skirmishers brought in a prisoner, who was arrested by Corporal Lowry, of Company G, while attempting to make his escape, and who, after making various contradictory statements-at first claiming to be a Union soldier, but not eking able to give the names of his immediate officers in command-finally admitted that he was a rebel soldier on picket duty; that his name is Williams, and that he belongs to the Fourteenth South Carolina Regiment. After being assured of his personal safety, and that the rebel accounts of cruelty on our side towards prisoners were false, he gave a great deal of information respecting the position and movements of the enemy, which statements, some of them quite improbable, were received by me for what they were worth, and himself forwarded a prisoner to headquarters.