a detachment from Griffin's and Barnes' brigades, under General Griffin, to cross the river at dark and carry the enemy's batteries. This was gallantly done under the fire of the enemy. Several guns, caissons, &c., were taken, and their supports driven back half a mile.

The information obtained during the progress of this affair indicated that the mass of the enemy had retreated on the Charlestown and Martinsburg roads toward Winchester. To verify this and to ascertain how far the enemy had retired, General Porter was authorized to detach from his corps, on the morning of the 20th, a reconnoitering party in greater force. This detachment crossed the river and advanced about a mile, when it was attacked by a large body of the enemy, lying in ambush in the woods, and driven back across the river with considerable loss. This reconnaissance showed that the enemy was still in force on the Virginia bank of the

Potomac, prepared to resist our further advance.

It was reported to me on the 19th that General Stuart had made his appearance at Williamsport with some 4,000 cavalry and six pieces of artillery, and that 10,000 infantry were marching on the same point from the direction of Winchester. I ordered General Couch to march at once with his division and a part of Pleasonton's cavalry, with Franklin's corps within supporting distance, for the purpose of endeavoring to capture this force. General Couch made a prompt and rapid march to Williamsport and attacked the enemy vigorously, but they made their escape across the river.

I dispatched the following telegraphic report to the General-in-Chief:

HEADQUARTERS ARMY OF THE POTOMAC,
Sharpsburg, September 19, 1862.

Major General H. W. HALLECK,

Commanding U. S. Army:

I have the honor to report that Maryland is entirely freed from the presence of the enemy, who have been driven across the Potomac. No fears need now be entertained for the safety of Pennsylvania. I shall at once occupy Harper's Ferry.

GEO. B. MCCLELLAN,

Major-General, Commanding.

On the following day I received this telegram:

WASHINGTON, September 20, 1862- 2 p. m.

Major General GEORGE B. MCCLELLAN:

We are still left entirely in the dark in regard to your own movements and those of the enemy. This should not be so. You should keep me advised of both, so far as you know them.

H. W. HALLECK,

General-in-Chief.

To which I answered as follows:

HEADQUARTERS ARMY OF THE POTOMAC,
Near Sharpsburg, September 20, 1862-8 p. m.

Major-General HALLECK,

General-in-Chief, Washington:

Your telegram of to-day is received. I telegraphed you yesterday all I knew, and had nothing more to inform you of until this evening. Williams' corps (Banks') occupied Maryland Heights at 1 p. m. to-day. The rest of the army is near here, except Couch's division, which is at this moment engaged with the enemy in front of Williamsport. The enemy is retiring via Charlestown and Martinsburg on Winchester. He last night reoccupied Williamsport by a small force, but will be out of it by morning. I think he has a force of infantry near Shepherdstown.

I regret that you find it necessary to couch every dispatch I have the honor to receive from you in a spirit of fault-finding, and that you have not yet hound leisure to say one word in commendation of the recent achievements of this army, or even to allude to them.