HEADQUARTERS HATCH'S BRIGADE,
Near Sharpsburg, September 23, 1862.

CAPTAIN: I herewith transmit a report of the action of this brigade in the engagement near Sharpsburg, Wednesday, September 17:

I took position with the other brigades of the division (Brigadier-General Doubleday commanding) Tuesday night, September 16, and the men slept on their arms. At 5.30 a.m. Wednesday the enemy's batteries opened upon our lines, and I was ordered by General Doubleday to move to the support of Gibbon's brigade, which had already advanced to attack the enemy's lines. Advancing through a belt of woods, in which Major-General Hooker and staff were stationed, and which was directly in rear of Campbell's (late Gibbon's) battery, I was ordered by General Hooker, who in person designated the position for this brigade to occupy, to move by flank through the open field in which this battery had taken position, and, passing into a corn-field, to form line of battle and support Gibbon's brigade, which observed was steadily advancing to the attack. The direct and cross artillery fire from the enemy's batteries playing upon this field was very heavy, but my brigade was moved without loss to a position some 90 paces in advance of Campbell's battery, where I deployed column, and in line of battle moved steadily forward some 50 paces in rear of Gibbon's infantry, who at this time had not engaged the enemy, but were cautiously advancing through the corn-field. This command consisted of the Second U. S. Sharpshooters (which was temporarily detached from the brigade during the engagement of Sunday), the Fourteenth New York State Militia, the Twenty-second, Twenty-fourth, and Thirtieth New York Volunteers.

Gibbon's brigade having engaged the enemy, who were posted in the road behind a line of fence, and sheltered by woods, I moved this brigade forward, and halted about 25 paces in rear of his line, ordering the men to lie down, and was prepared to move to his support when necessary.

Having ascertained that the enemy's line was formed with their left advanced, making a crotchet, and that they were in position to partially enfilade our lines, I ordered the Second U. S. Sharpshooters, Colonel Post, to move to the right and front, advancing his left, and to engage the enemy at that point. I immediately advised General Doubleday (in command of the division) of the enemy's position in front, on my right, and of the disposition of the Second U. S. Sharpshooters. General Doubleday approved the movement, and ordered a brigade to their right while the Sharpshooters were engaging them. The remainder of this brigade still held its position in the rear of Gibbon's line.

The effect of the engagement between the Sharpshooters and the enemy was to draw a very heavy fire from their advanced line, and I ordered the brigade forward to the support of the line in front. The musketry fire at this point was very heavy, but the two brigades appeared to hold their position easily. The loss of the Second U. S. Sharpshooters at this point was severe. The entire brigade suffered heavily in wounded, the proportion of killed being very small (see report of casualties in that engagement, already forwarded you), but, with General Gibbon's regiments, held their position until relieved by General Sedgwick's division, when I fell back slowly and in good order some 80 paces in rear of the corn-field, and again formed line of battle.

In this engagement Colonel Post was wounded, Adjutant Parmelee and Lieutenant Thompson killed-all of the Second U. S. Sharpshooters; Lieutenant Cushing, Twenty-second New York, killed; Captain