The capture of Vicksburg proved difficult partly because of the
topography of the area, which so favored defense of the city as to
render the fortress almost impregnable to attack. To move against the
city it was necessary to reach the bluffs which extended north and south
and on which Vicksburg had been built. Behind the bluffs, to the east,
lay dry ground on which an army might maneuver; below the bluffs, on
both sides of the river, flooded swamplands prevented ground movements.
With his army behind the bluffs, either above or below, Grant might come
to grips with Pemberton's Army of Vicksburg. Unless he reached the
bluffs, capture of the city would be impossible; it could not be
assaulted from the river.
The line of bluffs which marks the eastern boundary of the Mississippi
Valley leaves the river at Memphis, curves in a great 250-mile arc away
from the river, and then swings back to reach the river again at
Vicksburg. Enclosed between the bluffs and the river is the "Delta"--a
strip of land averaging some 60 miles in width, which is now a fertile,
well-drained, cotton-growing region. In 1863, it was a swampy bottom
land containing numerous rivers and bayous, subject to incessant floods.
It was covered with thick forests and dense undergrowth, a condition,
which, according to Grant's engineer officer, "renders the country
almost impassable in summer, and entirely so, except by boats, in
winter." This impenetrable swampland, lying before the bluffs,
effectively guarded Vicksburg's right flank. Unless the waterways of the
Delta might provide a passage to the bluffs, operations against
Vicksburg to the north were hopeless.
[Illustration: _Maj. Gen. U. S. Grant, commanding the Union Army of
the Tennessee._ Courtesy National Archives.]
[Illustration: _Lt. Gen. John C. Pemberton, commanding the
Confederate Army of Vicksburg._ Courtesy Flohr Studio, Vicksburg.]
South of Vicksburg the prospect for the Union Army was equally dismal.
After meeting the river at Vicksburg, the bluffs follow the river course
closely to the south and were accessible, therefore, to troops from the
Mississippi River. But the river batteries of the city prevented passage
of transports to the river below; for troops to get below the city it
was necessary to move through the Louisiana lowlands west of the river.
This region was like the Delta north of Vicksburg--flooded bottom lands
interspersed with bayous, rivers, and lakes. It would prove equally
obstinate to land movements.
To increase Grant's difficulties, his campaign against Vicksburg was
begun during the wet season when streams were overflowing and lowlands
impassable. The winter of 1862-63 was a period of unusually high water,
the Mississippi cresting higher than its natural banks from December
until April. Had Grant reached Vicksburg during the dry season, his
problem would have been less formidable.
Until the bottoms were dry enough to permit land movements, the Union
commander felt himself compelled to keep the army active. Even if
success along the water routes seemed unlikely, he reasoned that
prolonged idleness would be injurious to the health and morale of his
troops. Grant had come to believe that military success was won by the
aggressive. To Grant's critics, who demanded that he open the
Mississippi without delay or be replaced by someone who could, Lincoln
replied, "I can't spare this man; he fights."
As Pemberton prepared to defend Vicksburg he was beset by difficulties
rivaling those of his opponent, despite the topography which was
friendly to his defensive purpose. Vicksburg would be secure only so
long as the Confederate Army could prevent Grant from achieving a
foothold on the high ground above or below the city. Yet, to prevent
such a lodgment, it was necessary for Pemberton to defend a wide front
extending 200 miles above and below Vicksburg, at any point along which
Grant might strike. To cover this large area the Confederate commander
would have to disperse his limited garrison dangerously and at the same
time retain sufficient troops to protect the city--his primary
responsibility. Under such conditions it was essential for Pemberton to
receive information of Federal movements in order to concentrate his
troops rapidly to meet the advance. Yet Pemberton was almost wholly
lacking in cavalry and had no navy to interfere with and report Union
progress through the rivers and bayous. Both Pemberton and Grant faced
exacting problems in command during the Vicksburg operations.