se. General Halleck appreciated the situation and,
without being asked, forwarded reinforcements with all possible
dispatch.

The ground about Vicksburg is admirable for defence. On the north it is
about two hundred feet above the Mississippi River at the highest point
and very much cut up by the washing rains; the ravines were grown up
with cane and underbrush, while the sides and tops were covered with a
dense forest. Farther south the ground flattens out somewhat, and was
in cultivation. But here, too, it was cut up by ravines and small
streams. The enemy's line of defence followed the crest of a ridge from
the river north of the city eastward, then southerly around to the
Jackson road, full three miles back of the city; thence in a
southwesterly direction to the river. Deep ravines of the description
given lay in front of these defences. As there is a succession of
gullies, cut out by rains along the side of the ridge, the line was
necessarily very irregular. To follow each of these spurs with
intrenchments, so as to command the slopes on either side, would have
lengthened their line very much. Generally therefore, or in many places,
their line would run from near the head of one gully nearly straight to
the head of another, and an outer work triangular in shape, generally
open in the rear, was thrown up on the point; with a few men in this
outer work they commanded the approaches to the main line completely.

The work to be done, to make our position as strong against the enemy as
his was against us, was very great. The problem was also complicated by
our wanting our line as near that of the enemy as possible. We had but
four engineer officers with us. Captain Prime, of the Engineer Corps,
was the chief, and the work at the beginning was mainly directed by him.
His health soon gave out, when he was succeeded by Captain Comstock,
also of the Engineer Corps. To provide assistants on such a long line I
directed that all officers who had graduated at West Point, where they
had necessarily to study military engineering, should in addition to
their other duties assist in the work.

The chief quartermaster and the chief commissary were graduates. The
chief commissary, now the Commissary-General of the Army, begged off,
however, saying that there was nothing in engineering that he was good
for unless he would do for a sap-roller. As soldiers require rations
while working in the ditches as well as when marchi