Auburn to Catlett's Station, Va. I was immediately ordered by Colonel Brooke to move my regiment forward on the brow of the hill, and thus escape the well-directed fire of the enemy; also to about-face my regiment. This was quickly done, under the fire of the enemy's battery.

A few moments afterward I was ordered to about-face my regiment, and move forward on the road leading from Auburn to Greenwich, and countermarch my regiment, and thus have it right-in-front. This movement placed my regiment on the right of the brigade. After remaining in this position for some time, the enemy were seen advancing in our rear. I was ordered by Colonel Brooke to countermarch my regiment, and throw it forward as skirmishers, connecting on the right with those from the Second Delaware Volunteers, and on the left with those from General Carroll's brigade. After this movement was completed, the enemy opened a destructive fire upon us from a battery in front, doing us considerable damage. It was while in this position that all the casualties occurred in this regiment.

We remained in this position until about noon, when I was ordered by Colonel Brooke to assemble my regiment on the left, and follow the Sixty-fourth New York Volunteers on the road leading to Catlett's Station. Accordingly, I assembled my regiment and marched off in the manner ordered. We had gone but a short distance, when it was discovered that the enemy were advancing through the woods on the right of Kettle Run. I was immediately ordered by Colonel Brooke to move my regiment in a field on the right of the road and deploy it as skirmishers. This movement was quickly completed. The enemy seemed loth to advance after we had formed to meet him, but left us quietly in possession of the field.

Some time afterward I was ordered by Colonel Brooke to march my regiment in retreat as skirmishers, on the right of the road, connecting on the left, at the road, with the skirmishers of the Sixty-fourth New York Volunteers. We marched in this manner about 500 yards in rear of the column until we arrived at the railroad, when I was ordered to move my regiment as flankers. I kept up this manner of marching until we arrived within a mile of Bristoe Station, when I was ordered to assemble my regiment on the right and follow the Fifty-seventh New York Volunteers. This movement brought my regiment in rear of the brigade.

After our arrival at the station, I was ordered to form my regiment on the railroad on the left of the Fifty-seventh New York Volunteers. The position here chosen by Colonel Brooke was an excellent one, entirely protecting us from the fire of the enemy. A continuous fire was in progress between our skirmishers and those of the enemy while we remained in this position. In the night, about 11 o'clock, I received orders to march my regiment by the flank and follow the Fifty-seventh New York Volunteers. We crossed Broad [Run] and Bull Run, and arrived near Centreville about 4 o'clock on the morning of the 15th instant, where we bivouacked. I cannot speak too highly of both officers and men of this regiment, all doing their duty well.

I am, sir, very respectfully, your obedient servant,

H. S. DIMM,

Captain, Commanding Fifty-third Pennsylvania Volunteers.

Lieutenant CHARLES P. HATCH,

Acting Assistant Adjutant-General.