HARPER'S FERRY, VA.,

June 2, 1862.

SIR: I have the honor to report that, in obedience to your instructions of May 24, 1862, I assumed command of the forces at Harper's Ferry on the 26th of May. I found Colonel Miles occupying the place with one company of the Maryland Potomac Home Brigade. He had pushed forward that morning a battalion, composed of the First District of Columbia Regiment and One hundred, and eleventh Regiment Pennsylvania Volunteers, on the cars to Winchester, to re-enforce General Banks. They were too late, he having retreated, and they returned to Harper's Ferry. The same evening re-enforcements arrived, consisting of the Seventy-eighth New York, One hundred and ninth Pennsylvania, a naval battery of Dahlgren guns, under Lieutenant Daniels, U. S. Navy, and four companies of the Fifth New York Cavalry, from Winchester. On the 27th other troops arrived, with Captain Crounse's and Reynolds' battery of the First New York Artillery. I occupied Bolivar Heights with my troops and Maryland Heights with the naval battery. On the same evening I sent two companies of Colonel Maulsby's First Maryland Regiment, under Major Steiner, to make a reconnaissance of Loudoun Heights, where it was reported the enemy were in position.

They were fired upon whilst ascending, between 9 and 10 o'clock in the morning by dismounted rebel cavalry concealed in the bushes on both sides of the road. Sergeant Mehrling, of Company, I was killed. The fire was returned, with what effect was not known. Owing to the darkness of the night Major Steiner returned.

On Wednesday I shelled the Heights from Battery Stanton, compeling the enemy to retire, as was proved by a subsequent reconnaissance. In the course of the morning a reconnaissance in force was made toward Charleston by the One hundred and eleventh Pennsylvania Regiment, Colonel Schlaudecker, and the First Maryland Cavalry, Major Deems, and one section of Reynolds' battery. Our cavalry drove the enemy out of Charleston, but they were immediately re-enforced, and opening fire from a battery of nine guns, compelled our forces to retire, with a loss of 1 captain and 8 men captured by the enemy. The Seventy-eighth New York and the remaining pieces of Reynolds' battery were at once dispatched to cover their retreat, which was effected in good order without further injury, the enemy's battery following them to a point 2 miles distant from Charleston. They reported on their return the enemy advancing. Our troops were immediately formed in line of battle, extending along the crest of Bolivar Heights across the peninsula from the Potomac to the Shenandoah.

A body of the enemy's 2 cavalry was seen occasionally emerging from a point of woods about 2 miles distant, a little on the left of the road to Charleston. Clouds of dust were visible in various directions, as if the enemy were advancing. Our guns shelled the woods in front. The enemy made no response, but seemed, from their movements desirous of drawing us out from our position. Our men slept on their arms.

On the morning of the 29th the Fifth New York Cavalry was sent out to reconnoiter, and was fired upon by the enemy's infantry and artillery. Our pickets being driven, in our forces were again formed in order of battle, General Cooper's brigade on Bolivar Heights to the right, and General Slough's brigade to the left of the road leading to Charleston. After two or three hours, the enemy not appearing, a squadron of cavalry was sent out toward Halltown, before reaching