d a reorganization
of military commands and President Lincoln's Special War Order No. 3
consolidated the western departments of Hunter, Halleck, and Buell, as
far east as Knoxville, Tennessee, under the title of the Department of
the Mississippi, and placed General Halleck in command of the whole.
Meanwhile, Halleck had ordered the victorious Union army at Fort
Donelson to move forward to Savannah on the Tennessee River under the
command of Grant; and, now that he had superior command, directed Buell
to march all of his forces not required to defend Nashville "as rapidly
as possible" to the same point. Halleck was still at St. Louis; and
through the indecision of his further orders, through the slowness of
Buell's march, and through the unexplained inattention of Grant, the
Union armies narrowly escaped a serious disaster, which, however, the
determined courage of the troops and subordinate officers turned into a
most important victory.

The "golden opportunity" so earnestly pointed out by Halleck, while not
entirely lost, was nevertheless seriously diminished by the hesitation
and delay of the Union commanders to agree upon some plan of effective
cooeperation. When, at the fall of Fort Donelson the Confederates
retreated from Nashville toward Chattanooga, and from Columbus toward
Jackson, a swift advance by the Tennessee River could have kept them
separated; but as that open highway was not promptly followed in force,
the flying Confederate detachments found abundant leisure to form a
junction.

Grant reached Savannah, on the east bank of the Tennessee River, about
the middle of March, and in a few days began massing troops at Pittsburg
Landing, six miles farther south, on the west bank of the Tennessee;
still keeping his headquarters at Savannah, to await the arrival of
Buell and his army. During the next two weeks he reported several times
that the enemy was concentrating at Corinth, Mississippi, an important
railroad crossing twenty miles from Pittsburg Landing, the estimate of
their number varying from forty to eighty thousand. All this time his
mind was so filled with an eager intention to begin a march upon
Corinth, and a confidence that he could win a victory by a prompt
attack, that he neglected the essential precaution of providing against
an attack by the enemy, which at the same time was occupying the
thoughts of the Confederate commander General Johnston.

General Grant was therefore greatly surprised on