The protection of a line of communication is secured by combination
of passive and active measures, though the latter are of the greatest
importance.
Passive measures include the provision of fortified staging posts,
linked up by a series of road picquets, and supplemented by escorts to
convoys. The active defence is by means of flying columns.
Roughly speaking, it may be said that about 100 men per mile suffice
for all protective purposes, and it is assumed that the responsibility
of a staging post commandant extends half way to the posts on either
side of his own.
The garrison of a staging post must be of sufficient strength, and of
suitable composition, to secure the convoys halting there for the
night, to furnish them with police escorts for the next day's march,
and, if road picquets are found from the post, to supply these also.
Road picquets can either be sent out each day from staging posts,
can be permanently located in a succession of blockhouses, or can be
semi-permanent, that is to say can be supplied from a series of minor
posts connecting staging centres. In each of the above cases the same
number of men will be required.
The first method, by concentrating the troops each evening, makes for
their general security, but, since picquets must daily, and at fixed
hours, move to and from their places, a good deal of fatigue will be
imposed on the men, and there will, in addition, be some risk of minor
disasters to individual picquets, which may be ambuscaded. Moreover,
since the convoys cannot march until the picquets are in position, and
as picquets cannot be risked outside the post before sunrise and after
sunset, the hours available for the movements of the convoys will be a
good deal curtailed.
Under the second alternative, a weak cordon is formed, portions of
which cannot, owing to the topography, easily render one another
support in case any picquet is attacked in force. On the other hand, no
time will be wasted in posting and withdrawing picquets.
The third system is a compromise between the two already mentioned,
and seems, on the whole, to be the most advantageous. If three or
four relatively large posts are placed, in dangerous localities, such
as valley junctions, between staging centres, there will be little or
no risk of their capture by the enemy. Since the picquets necessary
to watch, by day, the area between the posts, will have but short
distances to traverse to reach their positions, the time available
for movement of convoys will not be curtailed; and as the ground
intervening between two posts will, in some degree, be overlooked
from them, there will be less chance, than under the first method, of
picquets falling into ambuscades.
The efficiency of the protection of a line of communication depends,
however, on the active, not on the passive measures for its security.
Active defence is maintained by flying columns, of strength and
organisation suitable to the character of the enemy and the nature of
the country. To these columns is confided the protection of certain
areas, an end attained, not by inactivity, for the troops should be
continually on the move, so that the enemy can never be certain when
and where to expect them, but by a vigorous and energetic offensive
in whatever directions an efficient service of intelligence reports
hostile gatherings.
The enemy's movements and projects must, in fact, be anticipated,
rather than countered when in course of execution.