At or near 5 p. m. we changed position, and formed near the burial ground west of the town. At or near 11 p. m. we changed our position, and, in compliance with orders, formed on the right of the Pughtown road, west of the fortification. We remained in that position until daylight of June 14. At or near 4 a. m. we formed under cover of a hill at a distance of some 400 yards north of our latter position, in order to feed and graze our horses. Remained in that position until 4 p. m., when Company I was thrown out as flankers on the left, and Company F relieved Company H as supporters of the regular battery. We then changed position toward the Pughtown road. At or near 5 p. m., being very much exposed to artillery fire of the enemy, we retired, in compliance with orders, toward the Martinsburg road, east of the fortification. At or near retreat, we crossed the Martinsburg road, and formed to charge upon a body of rebel cavalry which was coming toward us in the direction of Martinsburg. The enemy fell back and on the left of the Martinsburg road. At dark, we retired on the right and near earthworks or fort close to Martinsburg road, forming in line, and awaiting orders, an remained in that position until 2. 30 a. m., June 15. At the hour last mentioned, we moved on the Martinsburg road toward Martinsburg, covering the infantry, while the First New York Cavalry was still in our rear. At or near 4 a. m. the enemy opened fire among us with shell, when we changed position on the right, in front of the guns of the enemy, passing them to form on their left, in order to charge them in their rear, the enemy shelling ; us all the time. At one fire, Company A, composed of 62 men, lost every man excepting 9, including 2 commissioned officers. Seeing no other cavalry on the field, we withdrew toward Charlestown, arriving at Harper's Ferry at or near 12 m., with 301 and 20 officers, being a loss of 322 men and 12 officers.

I am, very respectfully, yours, &c.,

M. Kerwin,

Major, Comdg. Thirteenth Pennsylvania Cavalry.

Captain J. E. Jacobs,

A. A. G., First Brig., Second Div., Eighth Army Corps.

[Indorsement.]

Baltimore, Md., July 16, 1863.

Respectfully submitted with the following remark: The Thirteenth Pennsylvania Cavalry was not ordered by me to proceed within reach of the enemy's batteries, the fire of which is said to have proved so fatal to them.

R. H. Milroy,

Major-General.

Numbers 392.

Report of Lieutenant Jonathan B. Hanson, First Massachusetts Heavy Artillery, of operations June 10-15.

Maryland Heights, Md., June 23, 1863.

SIR: Company I, Fourteenth [First] Regiment Massachusetts Volunteer Heavy Artillery, Captain William F. Martins commanding,