ined Union forces was the reduction of Vicksburg, upon which the
authorities at Washington preferred to move by way of the river, as it
gave, under the convoy of the navy, an easy line of communication not
liable to serious interruptions. The Confederate line of which
Vicksburg was the centre then faced the river, the right resting on
Haines's Bluff, a strongly fortified position twelve miles away, near
to and commanding the Yazoo; while the left was on the Mississippi at
Grand Gulf, sixty miles below Vicksburg by the stream, though not over
thirty by land. The place, in the end, was reduced much in the same
way as Island No. 10; the troops landing above it on the opposite
bank, and marching down to a point below the works. The naval vessels
then ran by the batteries and protected the crossing of the army to
the east bank. A short, sharp campaign in the rear of the city shut
the Confederates up in their works, and the Union troops were able to
again secure their communications with the river above the town. There
were, however, grave risks in this proceeding from the time that the
army abandoned its water-base, adding to its line of communication
thirty miles of bad roads on the river bank, and then throwing itself
into the enemy's country, leaving the river behind it. It was
therefore preferred first to make every effort to turn the position
from the north, through the Yazoo country.

[Illustration: MISSISSIPPI VALLEY--HELENA TO VICKSBURG.]

The Yazoo Valley is a district of oval form, two hundred miles long by
sixty wide, extending from a short distance below Memphis to
Vicksburg, where the hills which form its eastern boundary again reach
the Mississippi. The land is alluvial and, when not protected by
levees, subject to overflow in ordinary rises of the river, with the
exception of a long narrow strip fifteen miles from and parallel to
the eastern border. It is intersected by numerous bayous and receives
many streams from the hills, all of which, from the conformation of
the ground, find their way first to the Yazoo River, and by it to the
Mississippi. The Yazoo is first called, in the northern portion of the
basin, the Cold Water, then the Tallahatchie, and, after receiving the
Yallabusha from the east, the Yazoo. In the latter part of its course
it is a large stream with an average width of three hundred yards, and
navigable always, for vessels drawing three feet of water, as far as
Greenwood, a distance of t