intrenchments.

SIEGES.

It is not proposed to go into historical or other details of this
branch of the subject, but to give in a condensed form some account of
siege operations. According to the text books, the first thing to be
done, if possible, in case of a regular siege, is to "invest" the
fortress. This is done by surrounding it as quickly as possible with a
continuous line of troops, who speedily intrench themselves and mount
guns bearing outward on all lines of approach to the fortress, to
prevent the enemy from sending in supplies or re-enforcements. As this
line must be at considerable distance from the fort, it is usually
quite long, and so is its name, for it is called the line of
"Circumvallation." Inside of this line is then established a similar
line facing toward the fort, to prevent sorties by the garrison. This
line is called the line of "Countervallation," and should be as close
to the fort as the range of its guns and the nature of the ground will
permit. From this line the troops rush forward at night and open the
trenches, beginning with what is called the first parallel, which
should be so laid out as to envelop those parts of the fort which are
to be made the special objects of attack. From this first parallel a
number of zigzag trenches are started toward the fort and at proper
intervals other parallels, batteries, and magazines are built; this
method of approach being continued until the besieged fort is reached,
or until such batteries can be brought to bear upon it as to breech
the walls and allow the attacking troops to make an assault.

During these operations of course many precautions must be observed,
both by the attacking and defending force, to annoy each other and to
prevent surprise, and the work is mostly carried on under cover of the
earth thrown from the trenches. These operations were supposed to
occupy, under normal conditions, about forty-one days, or rather
nights, as most of the work is done after dark, at the end of which
time the fort should be reduced to such a condition that its
commander, having exhausted all means of defense, would be justified
in considering terms of surrender.

The _Theoretical Journal_ of the siege prescribes just what is to be
done each day by both attack and defense up to the final catastrophe,
and this somewhat discouraging outlook for the defenders was forcibly
illustrated by the late Captain Derby, better known by the reading
public as