e
operations employed in the attack and defence of permanent
fortifications.

II. The attack and defence of a fortress may be carried on either by a
regular siege, or by irregular operations and an assault. The latter
plan has sometimes been adopted when the works of the place were weak
and improperly defended; where the time and means were wanting for
conducting a regular siege; or where the assailants were ignorant of the
means proper to be resorted to for the reduction of the fortress. Such
operations, however, are usually attended by an immense sacrifice of
human life, and the general who neglects to employ all the resources of
the engineer's art in carrying on a siege, is justly chargeable with the
lives of his men. In the siege of Cambrai, Louis XIV., on the
solicitation of Du Metz, but contrary to the advice of Vauban, ordered
the demi-lune to be taken by assault, instead of waiting for the result
of a regular siege. The assault was made, but it was unsuccessful, and
the French sustained great losses. The king now directed Vauban to take
the demi-lune by regular approaches, which was done in a very short
time, and with a loss of _only five men!_ Again, at the siege of Ypres,
the generals advised an assault before the breaches were ready. "You
will gain a day by the assault," said Vauban, "but you will lose a
thousand men." The king directed the regular works to be continued, and
the next day the place was taken with but little loss to the besiegers.

But a work may be of such a character as to render it unnecessary to
resort to all the works of attack which would be required for the
reduction of a regular bastioned fort, on a horizontal site. For
example: the nature of the ground may be such as to enable the troops to
approach to the foot of the glacis, without erecting any works whatever;
of course, all the works up to the third parallel may in this case be
dispensed with without any violation of the rules of a siege. Again, the
point of attack may be such that the other parts of the place will not
flank the works of approach; here a single line of _boyaux_ and short
parallels may be all-sufficient.

But for the purpose of discussion, we will here suppose the place
besieged to be a regular bastioned work on a horizontal site, (Fig.
54.)

The operations of the siege may be divided into three distinct periods.

1st. The preliminary operations of the attack and defence previous to
the opening of the trenches.