I accordingly left the Twelfth Corps at Harper's Ferry, detaching one brigade to the vicinity of Sharpsburg. General Morell was placed in command of the line from the mouth of the Antietam to Cumberland; General Slocum in command of Harper's Ferry and the line east of the mouth of the Antietam.

The orders given to these officers were as follows:

HEADQUARTERS ARMY OF THE POTOMAC,
October 29, 1862 - 1 p. m.

General H. W. SLOCUM,

Commanding Army Corps, Harper's Ferry:

The general commanding directs that you send one brigade of your corps to march at once to the position now occupied by General F. J. Porter's corps, in front of Sharpsburg, to watch and guard the line of the river from the ford near the mouth of the Antietam Creek to the mouth of the Opequon creek. The officer in command will also take steps to afford proper protection to the sick and wounded in the hospitals in the vicinity of Sharpsburg and Boonsborough. The regiment now at Boonsborough will be placed under his orders. General Kenly, at Williamsport, will guard the river from the mouth of the Opequon above, including the ford at the mouth of the Opequon.

The commanding general also directs that you take immediate steps to establish the remainder of your corps as follows, viz: One brigade on Maryland Heights, one brigade on Loudoun Heights, with the remainder on Bolilvar Heights and at Harper's Ferry.

These dispositions should be made at once, so that General Couch can move with his corps.

Please acknowledge the receipt of this.

R. B. MARCY,

Chief of Staff.

HEADQUARTERS ARMY OF THE POTOMAC,
October 31, 1862.

General GEORGE W. MORELL,

Commanding Upper Potomac:

GENERAL: I am instructed by the commanding general to say to you that he has selected you to perform the highly important and responsible duty of taking charge of and commanding the troops left for the defense of the line of the Potomac River, from the mouth of the Antietam to Cumberland, as well as any other troops that may hereafter be sent for the protection of the Maryland and Pennsylvania frontier, within the limits of the lines herein specified. The force which has been left to guard the line is not deemed adequate to prevent cavalry raids, but it is all that the commanding general feels authorized to detach from the Army of the Potomac at the present time, and it devolves upon you to make the best use of this force in your power. You will have four cavalry regiments under your command, which should be so distributed along the river as to watch all the available fords and give timely notice to the infantry of the approach of any force of rebels. You will afford all the protection in your power to the Baltimore and Ohio Railroad. You will endeavor to prevent any cavalry raids into Maryland and Pennsylvania. You will take steps to have all the sick and wounded of our army, as well as of the rebel army within your lines, properly taken care of until they can be sent to general hospitals, or discharged or paroled. You will make your headquarters at Hagerstown, and occasionally visit the different parts of your line. You will please report promptly to these headquarters everything of importance that occurs within the limits of your command. The three brigades now at Cumberland, Williamsport, and Sharpsburg, including the Fifty-fourth Pennsylvania Volunteers, near Cumberland, will be under your command. They are commanded by Generals Kelley, Kenly, and Gordon.

Very respectfully, your obedient servant,

S. WILLIAMS,

Assistant Adjutant General.

On the 25th of October the pontoon bridge at Berlin was constructed, there being already one across the Potomac and another across the Shenandoah, at Harper's Ferry.

On the 26th two divisions of the Ninth Corps and Pleasonton's brigade of cavalry crossed at Berlin and occupied Lovettsville. The First, Sixth, and Ninth Corps, the cavalry, and the reserve artillery crossed at Berlin between the 26th of October and the 2nd of November.s