the ditch
of the fort, which was ten feet deep, and at the angles formed a
fairly good listening gallery, but nothing unusual could be heard. I
therefore made arrangements to sink a line of pits in the bottom of
the ditch, something like ordinary wells; the bottoms of these pits to
be finally connected by a horizontal gallery which would envelop the
fort and enable us to hear the enemy and blow him up, before he could
get under the fort. Although the commanding officer of that fort was
as brave an officer as the war developed, he would not keep his men in
the fort after dark, but withdrew them quietly to the flanks of the
work, where they not only would be safe from an explosion, but would
be ready to fall upon the enemy in case he should blow up the fort and
rush in to capture the line, as our troops had attempted to do at
Petersburg. No explosion took place, however, and after our
countermining work was completed, the garrison became reassured and
remained in the fort at night as well as in day time. A few months
later, when the enemy was driven from his lines, I went through his
works to see whether any mining had been attempted, and found that a
gallery leading toward Fort Harrison had been carried quite a
distance, but was still incomplete, and it is barely possible that the
old miners were right, after all, in thinking that they could hear the
sound of the pick, although the distance was almost too great to make
this theory very probable.

Still another illustration of the way in which civil engineers can
make themselves extremely useful in military operations was the
wonderful system of military railways, or railways operated for
military purposes, that formed complete lines of transportation for
the armies and their enormous quantities of supplies and munitions,
more especially those in the West and Southwest. Construction trains
were organized in the most complete style, and when a piece of track
or a number of bridges were destroyed by the enemy, they would be
rebuilt so rapidly that our trains would hardly seem to be delayed by
it. The trains carried spare rails, ties, and bridges of various
lengths ready to put up, and they also carried the necessary rolling
stock and tools for destroying the roads and bridges of the enemy. So
expert had this construction corps become that the enemy was ready to
believe almost any statement in regard to it. General Sherman tells of
an instance where it was proposed to blow