The Forty-ninth Regiment New York Volunteers, on the morning of the 4th instant, repulsed an attack by three rebel regiments on their skirmish line, and captured the colors of the Fifty-eighth Virginia Volunteers, with 85 prisoners.

Our loss of arms and accouterments cannot as yet be accurately ascertained. We have also lost a considerable quantity of blankets, knapsacks, haversacks, and shelter-tents.

Very respectfully, your obedient servant,

THOS. H. NEILL,

Brigadier-General, Commanding Third Brigade.

Major CHARLES MUNDEE, Assistant Adjutant-General.

Numbers 231. Report of Lieutenant Colonel Winsor B. French, Seventy-seventh New York Infantry.

CAMP NEAR WHITE OAK CHURCH, VA., May 9, 1863.

SIR: In compliance with circular from brigade headquarters, issued this day, I have the honor to make the following report:

The Seventy-seventh New York Volunteers, forming a portion of the Third Brigade, Second Division, Sixth Corps, on the morning of the 3rd instant, then standing in line of battle on the main road leading from Fredericksburg south, was ordered to advance over the open plain at the foot of the high hills called Marye's Heights, as skirmishers, with a proper reserve, and occupy, if possible, a house and rifle-pits in the possession of the enemy's skirmishers and covered by their artillery. This was done quickly and with little loss; the enemy's skirmishers retreated, fighting. This position was held for some time, when the order came to advance, and was promptly obeyed. The regiment marched unhesitatingly on under a very severe fire of musketry and artillery. It being necessary to lengthen the line of skirmishers, and the Thirty-third New York coming up as a support, the whole regiment was deployed. and the right wing as such scaled the heights at the right of our line, occupying the earthworks, taking about 50 prisoners, among whom were Lieutenant-Colonel [William H.] Luse and 2 captains, and 1 stand of colors, belonging to the Eighteenth Mississippi. The left wing being unsupported, was rallied on the colors, and advanced quickly with slight loss up the heights on our left, occupying the earthworks, taking 25 prisoners, 2 pieces of artillery, and 2 limbers and limber-chests, on which heights the skirmishers of the right wing assembled on the left, and the regiment was formed, holding the heights, under a heavy fire from the enemy's cannon, with some loss. The regiment formed a portion of the reserve in the engagement on the evening of the same day beyond Fredericksburg and toward Chancellorsville.

On Monday, the 4th, the regiment was ordered to support a battery on the left, and near Fredericksburg, and during the engagement on the evening of the 4th. The regiment suffered but slightly in the engagement of the 4th, and fell back with the brigade in the direction of Banks' Ford, holding the enemy in check on its front at all times until ordered to fall back, recrossing the Rappahannock at near daylight on the 5th.

It gives me pleasure to say that the men under my command behaved well, and many of them gallantly. I have entire confidence in them,