me Tidball's four guns, to reply to the enemy's batteries, which had opened at four different points of their line. Tidball was soon placed in position, and returned fire, and this was continued at intervals on this and the succeeding day by numerous batteries engaged on both sides.

On the 16th instant my cavalry was engaged in reconnaissances, escorts, and supports to batteries.

THE BATTLE OF ANTIETAM.

On the morning of the 17th instant, after the commencement of the action on the right, I was directed by Major-General McClellan, verbally, to advance with my division of cavalry and horse batteries of artillery on the turnpike toward Sharpsburg, to some suitable position beyond the bridge over the Antietam Creek, and support the left of Sumner's line of battle with my force.

Finding the enemy had a cross-fire of artillery on the bridge, and that his sharpshooters covered it in front, I first threw forward some cavalry skirmishers, and then advanced Tidball's battery by piece, under a heavy fire, to drive off the sharpshooters with canister. This plan in a short time succeeded in clearing the front sufficiently to obtain positions for Gibson's, Robertson's, Tidball's, and Hains' batteries, who opened on the enemy with great effect, having a direct fire in front and an enfilading fire in front of Sumner's corps on the right, and supporting the right of Burnside's corps on the left, the distance to Sumner's corps being nearly a mile, and something greater to that of Burnside's, my force being the only one in front, connecting the two corps. The fire was kept up over two hours, when the enemy's fire had slackened very much, and my batteries, requiring ammunition, retired by piece and by section to supply themselves, being replaced by Randol's battery and Kusserow's battery, from Sykes' division. I was also indebted to General Sykes for five small battalions of infantry he kindly placed at my disposal, to assist in supporting my position.

The following cavalry supports were to the right and left of my position, viz: The Fifth Regular Cavalry, Farnsworth's brigade, Rush's brigade, and two regiments of the Fifth Brigade, under Colonel Davis, of the Eighth New York. About 3 o'clock in the afternoon three of my batteries, Tidball's, Robertson's, and Hains', returned to their positions, Randol's battery being relieved and Gibson's being placed in position on the right of the road, in rear, to cover the bridge.

The fight was then renewed with increased vigor and energy, the enemy's batteries being soon driven from their position in front of us. At the same time a heavy column of dust could be seen moving behind the Sharpsburg Ridge toward Sumner's left. I directed the fire of the batteries into this dust, and soon the development of the enemy's line of battle, fully a mile long, could be seen bearing down upon Richardson's division on Sumner's left, then commanded by Hancock, Richardson having been badly wounded. The enemy's batteries were also playing heavily upon this division.

At this time Hancock requested some guns to assist him. None could be spared at that moment, but I directed the fire of some eighteen guns upon the enemy's line in front of him for twenty minutes, when we had the satisfaction of seeing this immense line first halt, deliver a desultory fire, and then break and run to the rear in the greatest confusion and disorder. A section of Tidball's battery was immediately advanced to the crest of a hill several hundred yards to the front, and in front of