better
plan than the one actually carried out. Certainly the assumption
that the Ninth Corps could cross the Antietam alone at the only
place on the field where the Confederates had their line immediately
upon the stream which must be crossed under fire by two narrow heads
of column, and could then turn to the right along the high ground
occupied by the hostile army before that army had been broken or
seriously shaken elsewhere, is one which would hardly be made till
time had dimmed the remembrance of the actual position of Lee's
divisions upon the field. It is also noticeable that the plan as
given in the final report leaves no "centre" with which to "advance"
when either of the flank movements should be successful, Porter's
corps in reserve being the only one not included in the movement as
described.

Further evidence that the plan did not originally include the wide
separation of two corps to the right to make the extended turning
movement is found in Hooker's incomplete report, and in the wide
interval in time between the marching of his corps and that of
Mansfield. Hooker was ordered to cross the Antietam at about two
o'clock in the afternoon of the 16th by the bridge in front of
Keedysville and the ford below it. He says that after his troops
were over and in march, he rode back to McClellan, who told him that
he might call for reinforcements, and that when they came they
should be under his command. Somewhat later McClellan rode forward
with his staff to observe the progress making, and Hooker again
urged the necessity of reinforcements. [Footnote: Official Records,
vol. xix. pt. i. p. 217.] Yet Sumner did not receive orders to send
Mansfield's corps to his support till evening, and it marched only
half an hour before midnight, [Footnote: _Id_., p. 275.] reaching
its bivouac, about a mile and a half in rear of that of Hooker, at 2
A.M. of the 17th. [Footnote: _Id_., p. 475.]

After crossing the Antietam, Hooker had shaped his course to the
westward, aiming to reach the ridge on which the Hagerstown turnpike
runs, and which is the dominant feature in the landscape. This ridge
is about two miles distant from the Antietam, and for the first mile
of the way no resistance was met. However, his progress had been
observed by the enemy, and Hood's two brigades were taken from the
centre and passed to the left of D. H. Hill. Here they occupied an
open wood (since known as the East Wood) northeast of the Dunker
Churc