Numbers 4. Report of Colonel George A. H. Blake,

First U. S. Cavalry, commanding Second Brigade, of the battle of Gaines' Mill.

HEADQUARTERS SECOND CAVALRY BRIGADE,
Camp, Harrison's Landing, James River, Va., July 3, 1862.

SIR: In compliance with orders from the headquarters cavalry division I have the honor to report the movements of this brigade on the 26th instant and its engagement with the enemy on the following day.

The brigade consisted of two small squadrons of the First U. S. Cavalry, commanded by Lieutenant-Colonel Grier, and the provost guard of the division, consisting of 39 men, under the command of Lieutenant Balk, Sixth U. S. Cavalry. On the 26th instant information was received of the approach of the enemy, who we were informed were seen upon the road in our rear. The brigade was immediately formed. About 12 o'clock m. we took up the line of march and reached Cold Harbor, where we remained for the night.

About 7 o'clock upon the following morning (June 27) the line of march was again resumed, and we proceeded to a point which was then occupied for the time by General F. J. Porter as his headquarters, on the road leading to Numbers 8 Bridge. The brigade was placed in position, and about 11 o'clock the engagement commenced. A short time after the brigade was moved to the left and rear of the house occupied by General F. J. Porter as his headquarters. Late in the evening, when our infantry retired before the overwhelming numbers of the enemy, the brigade was ordered upon the hill in rear of the Fifth U. S. Cavalry, with orders to act as a reserve to the Fifth Cavalry, who were ordered to charge the enemy, and, if successful, to take advantage of it and follow it up. The fire of the enemy was so destructive that a charge was not effected. The command fell back with the artillery in good order and occupied a position about 600 yards from our former position. We were again ordered to the front, and acted as a support to a body of infantry who had rallied at the bottom of the hill and were holding the enemy in check. When our artillery was posted on the hill in rear we were ordered to retire, so as to be out of his fire. We fell back a short distance and remained until 1 o'clock a.m. on the 28th instant, when the command retired across the Chickahominy, near Savage Station.

I am indebted to Lieutenant-Colonel Grier, Captain Reno, Captain Kellogg, Lieutenant Feilner, Lieutenant Allen (dangerously wounded), all of the First U. S. Cavalry; Lieutenant Balk, Sixth U. S. Cavalry, and lieutenant Kneass, acting, assistant adjutant-general Eighth Pennsylvania Volunteer Cavalry, for the prompt and cheerful assistance given me on the field. Lieutenant Balk and myself were slightly struck during the engagement, but not of sufficient importance to notice further.

A list of casualties will be furnished when received.

I am, sir, very respectfully, your obedient servant,

GEO. A. H. BLAKE,

Colonel First Cavalry, Commanding Brigade.

Lieutenant JAMES P. MARTIN.