No. 184. Report of Lieutenant Colonel Robert C. Buchanan, Fourth U. S. Infantry, commanding First Brigade.

HEADQUARTERS FIRST BRIGADE, REGULAR INFANTRY, Camp near Henry House, Va., December 19, 1862.

SIR: I have the honor to submit the following report of the operations of my brigade during the battle of Fredericksburg, Va.:

The brigade, consisting of the Third and Fourth Regiments, the First and Second Battalions of the Twelfth, and First and Second Battalions of the Fourteenth Infantry, led the advance of the division across the Rappahannock about 4 p.m. on Saturday, the 13th instant, and, after crossing, was moved to the rear of the city by way of Hanover street. On reaching the intersection of this and George street, I was ordered to place my command under cover on this latter street, which I did. Directly after the repulse of Humphreys' division, I was ordered to form my brigade in line of battle in rear of the ditch between Hanover street and the Plank road bridges, and take the enemy's batteries in front at the point of the bayonet. I accordingly formed my line as directed, and notified my brigade of what we were about to do, but before the line, which it was necessary to form by a flank movement, was fully established, I received orders not to advance until further orders, and to keep my men under cover of the ditch. As my command covered more than this space in line, I threw the Third and Fourth Infantry into the cemetery, under cover of the front wall.

About 11 p.m. I was ordered to occupy the line on the crest of the first hill, then occupied by the brigade of Colonel Hall, which was the extreme point that our troops had reached on that side of the Hanover street road.

My command was in position by 12.30 a.m., and remained there until relieved the next night by a portion of Sully's brigade. The position occupied by my brigade was the crest of a hill, terminating on the Hanover street road on the left, and a brick tannery on the Plank road, on the right, and about 250 yards from a stone wall and series of rifle-pits, covering the entire front occupied by the enemy. The ground was slightly descending toward us, and another small hill, rising above it in front, protected by a small field-work, holding two guns, commanded its entire surface. Batteries on other hill on my right enfiladed not only the position occupied by my brigade, but the ground in front also. The ditch, in rear of which I first formed, was about 200 yards in rear, and was about 6 feet wide and 10 feet deep, with some 4 feet of water in it. Between my command and this ditch the ground was a plain, sloping toward it, and this again intersected by another ditch, about 4 feet and 3 feet deep, running through its middle at right angles to the larger one. The enemy occupied some small frame houses on the right of the Plank road, from which they could annoy our line very much. At daylight firing commenced between the pickets, and it was soon found that my position was completely commanded, so that if an individual showed his head above the crest of the hill he was picked off by the enemy's sharpshooters immediately, especially by those on the right.

About 11 a.m. the Third and Fourth Infantry effected an entrance into the tannery with their bayonets, through the brick wall next to Hanover street, and soon after loop-holed the wall on the Plank road, and occupied the windows fronting the enemy, and from these positions drove him from the house and rifle-pits on the right, so that he could not occupy them again during the day.

The most trying test of discipline and courage is to place men in a situation where they are compelled to endure the steady fire of an enemy without having it in their power to return it. This was the case with my command on Sunday, the 14th instant, for soon after the firing commenced I ordered my men not to fire unless they saw something to fire at, with a probability of success, and they obeyed the order as it was given, although their companies comrades were shot down by their side at every moment. For this I ask that they receive credit such as is their due.

The enemy shot my men after they were wounded, and also the hospital attendants as they were converging the wounded off the ground, in violation of every law of civilized warfare. My loss would have been much greater but for our taking possession of the tannery. I was to hold the position to the last extremity, and it was held until after I was relieved by other troops. The enemy was so posted that he virtually cut off all intercourse between my brigade and the city between the break of day and nightfall. My dead were buried on the ground and my wounded brought away.

On the 15th, my brigade was posted in the city and about midnight was designated as the rear guard of the army in its withdrawal to this side of the Rappahannock. This duty was accomplished without loss, save of some stragglers from various volunteer divisions in the field. The straggling was excessive, and the completion of the movement delayed nearly two hours thereby. Why more of them were not captured by the enemy I am at a loss to understand.

We reached this side of the river at 8 a.m., and as soon as the brigade had crossed my rear guard, consisting of one company of the Twelfth and two of the Third, under the command of Captain F. Winthrop, Twelfth Infantry, was ordered across,and the bridge broken up and removed. Some few stragglers made their appearance on the bank after the bridge was broken up, and were brought over in the pontoon boats.

My loss was 2 officers, Lieutenants Benedict and Gensel, Fourth Infantry, severely wounded, and 49 non-commissioned officers and privates killed and wounded.

When all behaved so well it is hard to make distinctions, but I would call attention to First Lieutenant A. R. Benedict, Fourth Infantry, who was wounded while withdrawing his outer picket to place it under cover, after having had 7 or his men wounded.

The reports of the regimental commanders are herewith inclosed.

My staff, consisting of First Lieuts. William H. Powell, Fourth Infantry, acting assistant adjutant-general, and S. Van Rensselaer, Twelfth Infantry, acting aide-de-camp my orders with zeal and alacrity, and discharged their duties to my entire satisfaction.

I am, sir, respectfully, your obedient servant,

ROBT. C. BUCHANAN,

Lieutenant-Colonel Fourth Infantry, Commanding Brigade.

Captain GEORGE RYAN,

Actg. Asst. Adjt. General, Second Division, Fifth Corps.