Maj. Gen. James Longstreet. Courtesy, Library of Congress.

Maj. Gen. Thomas J. "Stonewall" Jackson. From photograph by George W Minnes. Courtesy, Library of Congress.

The Lost Order

Lee's army departed Frederick on September 10. Two days later leading elements of McClellan's army entered that city. On September 13, came McClellan himself with his usual cavalcade of staff officers.

That same afternoon a copy of Lee's Special Order 191 was discovered in the encampment grounds previously used by the Confederate army. Quickly it was passed to McClellan. The handwriting was recognized as that of Col. R. H. Chilton, Lee's assistant adjutant general; the document's authenticity could not be doubted.

The fate of Lee's army literally lay in McClellan's hands. If he slashed swiftly through the South Mountain gaps and planted his army squarely between Longstreet's force near Hagerstown and Jackson's columns at Harpers Ferry, he could overwhelm the Confederate detachments in turn.

But again McClellan was methodical. Not until the next morning, September 14, did his heavy columns get underway. This crucial delay was to give Lee the chance to pull his army together at the small town of Sharpsburg.