attacking army, which having to secure itself along an extended line,
was left everywhere too weak to resist a sally made from the town; nay,
of itself, was apt to fall into confusion and disorder. This method of
attack, therefore, could be attempted once only and by way of surprise.

Against breaches in the walls the defence was, as at the present day, to
throw up new works; while mines were met by counter-mines, in which the
enemy were either withstood at the point of the sword, or baffled by
some other warlike contrivance; as by filling casks with feathers,
which, being set on fire and placed in the mine, choked out the
assailants by their smoke and stench. Where towers were employed for the
attack, the defenders sought to destroy them with fire; and where mounds
of earth were thrown up against the walls, they would dig holes at the
base of the wall against which the mound rested, and carry off the earth
which the enemy were heaping up; which, being removed from within as
fast as it was thrown up from without, the mound made no progress.

None of these methods of attack can long be persisted in and the
assailant, if unsuccessful, must either strike his camp and seek victory
in some other direction, as Scipio did when he invaded Africa and, after
failing in the attempt to storm Utica, withdrew from his attack on that
town and turned his strength against the Carthaginian army in the field;
or else recourse must be had to regular siege, as by the Romans at Veii,
Capua, Carthage, Jerusalem, and divers other cities which they reduced
in this way.

The capture of towns by stratagem combined with force is effected, as
by the Romans at Palæopolis, through a secret understanding with some
within the walls. Many attempts of this sort have been made, both by the
Romans and by others, but few successfully, because the least hindrance