Emory with the Sixth Cavalry, to from a portion of the cavalry force of the advance guard of that portion of the army designed to operate in the direction of Hanover Court-House, under Major-General Porter. We marched about 7 o'clock on the 27th, and about 12 came up with the enemy at Winston's farm, about 2 miles from Hanover Court-House. A short engagement ensued, in which the Sixth Cavalry was for a time exposed to a very correct, though fortunately not a very destructive, fire from the enemy's battery. Whilst supporting Benson's artillery Private Smith, of Company H, and 2 horses were wounded. The enemy soon retreated in the direction of Hanover, which point was occupied by a squadron of the Sixth Cavalry under Captains Sanders and Hays. Whilst pushing the enemy in his retreat, which had now become very rapid, the advance guard was recalled, in consequence of a force attacking our rear. The pursuit was abandoned. The Sixth Cavalry camped on the evening of the 27th on the battle-field.

On the morning of the 28th I was ordered to burn the railroad bridge over the South Anna River. I proceeded with four squadrons of the Sixth Cavalry to Wickham's farm with materials for firing the bridge. The nature of the ground being such as to preclude a large cavalry force acting with safety or advantage, Lieutenant Kerin was ordered to take a platoon, supported by the regiment, and fire the bridge if possible. Although a work of great labor it was done in about three hours, completely destroying the railroad communication.

At 12 o'clock on the night of the 28th Lieutenant Kerin left the camp with about 20 men, and successfully fired and destroyed the county bridge about 200 yards above the railroad crossing. He was assisted in both operations by Lieutenant Coats, and both deserve the highest praise for the effectual manner in which they discharged their duty. Another bridge was also burned by Captain Cram. This was a bridge which Rush's Lancers had fired on the 27th, but owing to the suddenness of their having withdrawn from the front were unable to entirely complete its destruction.

On the night of the 28th I received instructions to destroy another bridge over the South Anna, over which passed the Virginia Central Railroad. The enemy were supposed to be in force at this bridge. A section of artillery under Lieutenant Hains and four companies of the New York Seventeenth were added to my command. With this force I proceeded to the cross-roads leading to Ashland, Taylorsville, and the bridge. It having been reported that 8,000 rebels were at Ashland, a force probably at the bridge, and one also at Taylorsville, I determined not to give up my position on the main road. Captain Abert's squadron was ordered in advance as a reconnoitering party. The three roads were well scoured, the firing of the bridge found practicable, and effected by Captain Abert in about an hour. Captain Kautz' squadron supported Captain Abert during the operation. My force then returned to camp, and the Sixth Cavalry on its arrival there ordered to the present one, a distance of 14 miles, which we reached at 12.30 o'clock at night, having been in the saddle eighteen out of the twenty-four hours.

I am, sir, with great respect,

LAWRENCE WILLIAMS,

Major, Sixth Cavalry, Commanding.

ACTING ASSISTANT ADJUTANT-GENERAL,

Advance Guard, near New Bridge, Va.