“Receiving nothing from Harper’s Ferry or Martinsburg to-day, and positive information from Wheeling that the line is cut, corroborates the idea that the enemy is recrossing the Potomac. Please do not let him get off without being hurt.”[57]
Elsewhere General McClellan has written of the 12th:
“During these movements I had not imposed long marches on the columns. The absolute necessity of refitting and giving some little rest to the troops worn down by previous long-continued marches and severe fighting, together with the uncertainty as to the actual position, strength, and intentions of the enemy, rendered it incumbent upon me to move slowly and cautiously until the head-quarters reached Urbana, where I first obtained reliable information that the enemy’s object was to move upon Harper’s Ferry and the Cumberland Valley, and not upon Washington and Baltimore.”
His army was organized: Right wing, under General Burnside: First and Ninth Corps; the Kanawha Division, under General J. D. Cox, was assigned with the Ninth Corps about the 8th instant.
Centre column: Second and Twelfth Corps, under General Sumner.
Left wing: Sixth Corps and Couch’s division of the Fourth under General Franklin; Sykes’s division, Fifth Corps, independent.[58]
Besides the despatches of the 11th and 12th, his cavalry under General Pleasonton, which was vigilant and pushing, sent frequent reports of his steady progress. In the afternoon Pleasonton and the Ninth Corps under General Reno entered Fredericktown. This advance, by the National road, threatened to cut off two of Stuart’s cavalry regiments left at the Monocacy Bridge. To detain the enemy till these were withdrawn, the outpost on that road was reinforced. Hampton retired his cavalry beyond Frederick and posted his artillery to cover the line of march, where he was soon attacked by a formidable force. To make safe the retreat of the brigade, a cavalry charge was ordered, under Colonel Butler, Lieutenant Meaghan’s squadron leading. Colonel Moore, of the Twenty-eighth Ohio Cavalry, and a number of other prisoners were captured. This so detained the enemy as to give safe withdrawal for the brigade to Middletown, leaving Lieutenant-Colonel Martin’s cavalry and two guns on guard at the gap of the Catoctin range of mountains.
Before withdrawing from Frederick on the 12th, General Stuart sent orders for the brigade under General Fitzhugh Lee to move around the right of the Union army and ascertain the meaning and strength of its march.
Following his orders of the 12th, General Pleasonton detached a cavalry brigade on the 13th and section of artillery under Colonel McReynolds to follow Fitzhugh Lee, and Rush’s Lancers were sent to Jefferson for General Franklin’s column. With his main force he pursued the Confederates towards Turner’s Pass of South Mountain. Midway between Frederick and South Mountain, running parallel, is a lesser range, Catoctin, where he encountered Stuart’s rear-guard. After a severe affair he secured the pass, moved on, and encountered a second force near Middletown. Reinforced by Gibson’s battery, he attacked and forced the way to a third stand. This in turn was forced back and into the mountain at Turner’s Pass.
On that day McClellan’s columns marched: Ninth Corps, to and near Middletown, eight miles; First Corps, to the Monocacy, eight miles; Twelfth Corps, to Frederick, nine miles; Second Corps, to Frederick, eight miles; Sixth Corps, to Buckeystown, seven miles; Couch’s division, to Licksville, six miles; Sykes’s division, to Frederick, eight miles.