No. 95. Report of Lieutenant Colonel Robert C. Buchanan, Fourth U. S. Infantry, commanding First Brigade, of the battle of Antietam and skirmish at Shepherdstown Ford.

HEADQUARTERS FIRST BRIGADE REGULAR INFANTRY, Camp near Sharpsburg, Md., September 26, 1862.

SIR: I have the honor to submit the following report of the operations of the First Brigade, consisting of the Third and Fourth Infantry, First and Second Battalions of the Twelfth, and First and Second Battalions of the Fourteenth, since leaving Middletown, Md., on the 15th instant.

The brigade crossed South Mountain and reached Porterstown on the 15th, and was placed in position in advance of that place on its arrival. The Third Infantry was thrown out as skirmishers to cover the position. The next morning the Fourth was advanced to the bridge on the turnpike to Sharpsburg crossing the Antietam, to hold it and prevent any attempt of the enemy to destroy it, the Third being brought back to the brigade. Three companies of the Fourth were thrown across the brigade and deployed as skirmishers, the remaining companies being posted on the left of it.

On the morning of the 17th the First Battalion of the Twelfth relieved the Fourth, which then rejoined the brigade. In the afternoon the Fourth and both battalions of the Fourteenth were sent across the bridge, under the command of Captain H. Dryer, commanding Fourth Infantry, who was directed to take with him also the First Battalion of the Twelfth from its position at the brigade, and to take command of any other regular infantry that might be there, to support some batteries of artillery on that side, under the command of Brigadier-General Pleasonton, Volunteers, which was done. At night this command was relieved by a portion of Morell's division of Volunteers, and rejoined the brigade. During the 18th the brigade remained in its first position in front and to the left of Porterstown. On the 19th the brigade moved forward across the brigade and through Sharpsburg to the bank of the Potomac, in pursuit of the retreating enemy. Lieutenant Carlton, Fourth Infantry, with two companies of that regiment, was moved forward in advance, in order to ascertain whether any force of the enemy was in our front, but found none, though he succeeded in capturing several prisoners.

Detailed reports of the operations of the several portion of the brigade are herewith inclosed.

During the afternoon of the 16th many shot and shells were thrown into the brigade, but they did no damage. The officers and men of my command behaved, as usual, with coolness and courage, and are deserving of all praise for the cheerful manner in which their duties were discharged.

To my staff, First Lieutenant S. Van Renseelaer, Twelfth Infantry, acting aide-de-camp, and Second Lieutenant William H. Powell, Fourth Infantry, acting assistant adjutant-general, my thanks are due for the cheerful alacrity and coolness with which they carried my orders to the different portions of the brigade.

I am, sir, respectfully, your obedient servant,
ROBT. C. BUCHANAN,

Lieutenant-Colonel Fourth Infantry, Commanding Brigade.

First Lieutenant HEYWARD CUTTING,

Tenth Infantry, Acting. Asst. Adjt. General, Sykes' Division.