On being given command of the combined Union forces at and
about Washington, McClellan again had a large and splendidly equipped
army under him. He at first exhibited some energy in moving it
into Maryland after Lee, but by his extreme caution and delays
suffered Harper's Ferry to be taken (September 15, 1862), with
10,000 men and an immense supply of arms and stores, and finally,
when fortune smiled on his army at Antietam, he allowed it to lay
quietly on its arms a whole day and long enough to enable Lee to
retreat across the Potomac, where he was permitted to leisurely
withdraw, practically unmolested, southward. The critical student
of the battle of Antietam will learn of much desperate fighting on
both sides, with no clearly defined general plan of conducting the
battle on either side. As Lee fought on the defensive, he could
content himself with conforming the movements of his forces to
those of the Union Army. Stonewall Jackson, after maintaining a
short, spirited battle against Hooker's corps, withdrew his corps
from the engagement at seven o'clock in the morning and did not
return to the field until 4 P.M.( 1)

Generally the Union Army was fought by divisions, and seldom more
than two were engaged at the same time, often only one. In this
way some of the divisions, for want of proper supports, were cut
to pieces, and others were not engaged at all. Acting on interior
lines, Lee was enabled to concentrate against the Union attacks
and finally to repulse them. Notwithstanding this mode of conducting
the battle, the Confederate Army was roughly handled and lost
heavily.

General Ambrose E. Burnside late in the day succeeded in crossing
Antietam Creek at the Stone Bridge and planting himself well on
the Confederate right flank. McClellan also had, at night, many
fresh troops ready and eager for the next day's battle. Considerable
parts of his army had not been engaged, and reinforcements came.
The two armies confronted each other all day on the 18th, being
partly engaged in burying the dead, as though a truce existed, and
at night Lee withdrew his army into Virginia.( 2)

Indecisive as this battle was, it is ever to be memorable as, on
its issue, President Lincoln kept a promise to "himself and his
Maker."( 3) On September 22, 1862, five days later, he issued a
preliminary proclamation announcing his purpose to promulgate,
January 1, 1863, a war measure, declaring free the slaves in all
States or p