the remainder of his
corps, was at Boonsboro or near Hagerstown. D. H. Hill's division
was the rear-guard, and the cavalry under Stuart covered the whole,
a detached squadron being with Longstreet, Jackson, and McLaws each.
The order did not name the three separate divisions in Jackson's
command proper (exclusive of Walker), nor those remaining with
Longstreet except D. H. Hill's; but it is hardly conceivable that
these were not known to McClellan after his own and Pope's contact
with them during the campaigns of the spring and summer. At any
rate, the order showed that Lee's army was in two parts, separated
by the Potomac and thirty or forty miles of road. As soon as Jackson
should reduce Harper's Ferry they would reunite. Friday the 12th was
the day fixed for the concentration of Jackson's force for his
attack, and it was Saturday when the order fell into McClellan's
hands. Three days had already been lost in the slow advance since
Lee had crossed Catoctin Mountain, and Jackson's artillery was now
heard pounding at the camp and earthworks of Harper's Ferry. McLaws
had already driven our forces from Maryland Heights, and had opened
upon the ferry with his guns in commanding position on the north of
the Potomac. [Footnote: _Id_., p. 607.] McClellan telegraphed to the
President that he would catch the rebels "in their own trap if my
men are equal to the emergency." [Footnote: Official Records, vol.
xix. pt. ii. p. 281.] There was certainly no time to lose. The
information was in his hands before noon, for he refers to it in a
dispatch to Mr. Lincoln at twelve. If his men had been ordered to be
at the top of South Mountain before dark, they could have been
there; but less than one full corps passed Catoctin Mountain that
day or night, and when the leisurely movement of the 14th began, he
himself, instead of being with the advance, was in Frederick till
after 2 P.M., at which hour he sent a dispatch to Washington, and
then rode to the front ten or twelve miles away. The failure to be
"equal to the emergency" was not in his men. Twenty-four hours, as
it turned out, was the whole difference between saving and losing
Harper's Ferry with its ten or twelve thousand men and its
unestimated munitions and stores. It may be that the commanders of
the garrison were in fault, and that a more stubborn resistance
should have been made. It may be that Halleck ought to have ordered
the place to be evacuated earlier, as McClellan suggeste