The idea of the screen is first touched on in the "Field Service
Manual" of 1908; it is also, however, demanded by the conditions of
modern war. For however important it may be to gain early intelligence
as to the enemy in order thereby to be able to make the necessary
dispositions, it is naturally just as important to deprive him of this
advantage. Reflection and experience have shown that although the
measures of reconnaissance considerably assist the screening if the
enemy's cavalry is defeated, they are not of themselves sufficient to
secure the army from hostile observation.
The "Field Service Manual" sums up, I think, the chief considerations
as regards screening, for the most part to the point, especially
where it deals with the defensive screen. There are no war experiences
in modern times of this matter, and, according to my opinion, peace
experiences are not comprehensive enough to allow of any appreciable
amplification of the "Field Service Manual."
At the same time I would draw attention to some of the points which
give occasion for further research and reflection.
In the first place, I think that what the "Field Service Manual" says
as to offensive screens requires some explanation. Strong cavalry will
be concentrated to keep the enemy at a distance from our own army.
_In addition to this_, strong patrols and even cyclist detachments
advance along all roads in order to throw back the hostile patrols.
These arrangements can only apply, as a rule, for portions of the _army
cavalry_. They presuppose, especially if the front of the modern army
is to be screened, a mass of cavalry which could with difficulty be
found from the divisional cavalry. By such methods, moreover, as long
as strong cyclist detachments are not available for blocking the road
communications, a cause of dissension will always arise as to how much
strength can be used for blocking the roads and how much concentrated
for battle, all the more so as the divisional cavalry can only with
difficulty be used in this kind of screen.
The latter must, as we have seen, remain more or less locally tied
to the division. The army cavalry, however, if it will undertake an
offensive screen, must advance against the enemy, seek him out, force
him back as far as possible from our own army, and endeavour to defeat
him. For this task complete freedom of movement is necessary--not only
for itself, but also for the screen of patrols that will accompany
it. The divisional cavalry will thus generally only be able to form
a second screening line behind the veil formed by the advancing army
cavalry, and will not be in a position to spare for it patrols for the
blocking of roads. Nor is it at all clear where the cyclist troops
mentioned are to come from.
I am therefore inclined to think that the procedure advocated by the
"Field Service Manual" can only be carried out in exceptional cases;
and it would perhaps be advisable to alter it somewhat.
The principal task of the offensive screen is, according to my opinion,
to defeat the hostile cavalry; and for this object all available force
must be concentrated, for one cannot be too strong upon the field of
battle. Even such cyclist detachments as are available will be best
used by bringing them up for the fight. The blocking of roads, on
the other hand, will, as a rule, be only undertaken when the enemy's
cavalry has been beaten and thrown back. The screen of patrols can then
be strengthened. But it must be quite clearly understood that troops
are not to be simply disposed in a cordon; but that a sufficiently
strong force must still remain in touch with the beaten enemy in order
to prevent him, at all events, from taking up the offensive again, and
breaking through the screen.
Until this moment of victory over the hostile cavalry the duties
of screening must be left to the reconnoitring organs and to the
divisional cavalry of the army which is following in rear of them.
According to the principles laid down in the "Field Service Manual"
it is to the divisional cavalry that the task invariably falls of
screening the movements of its division. I think that these duties
cannot always be clearly regulated according to the idea of an
offensive or defensive screen; they will more often be of a mixed
nature. As far as its strength will admit, the divisional cavalry
will endeavour to carry out the task by pushing back, by fighting,
the hostile reconnoitring patrols and detachments before these have
succeeded in gaining observation. As it is more or less locally
confined to its own front, and will certainly often have to do with an
opponent of superior strength, it will, on the other hand, frequently
be obliged to join battle for favourable localities dismounted,
supported whenever possible by machine-guns and cyclists from the
infantry. In situations where the divisional cavalry cannot undertake
an offensive fight against the superiority of the enemy, and can find
no _points d'appui_ in the terrain, it must try all the more to block
the roads with patrols which will attack all hostile patrols with the
utmost determination, and endeavour to capture their despatch-riders.
The divisional cavalry must show the greatest boldness and judgment if
it will carry out this task. The great importance of its rôle in the
army here again becomes obvious.
The army cavalry will only undertake an offensive screen when the army
is advancing, and where the country does not afford suitable localities
for the establishment of a defensive screen.
Such a screen (defensive), which can eventually be pushed forward from
one area to another, is without doubt, as is emphasised by the "Field
Service Manual," of much more use than an offensive screen.
Of great importance in a defensive screen is, first and foremost,
the nature of the obstacles on which it is based. Watercourses and
canals, which can only be crossed by bridges, form the best of these.
Extensive woods, however, lend themselves easily to the purpose. They
are doubtless, for cavalry patrols, a most unpleasant obstacle, as
view is restricted in them, and an ambush may lurk behind every tree.
In the campaign of 1870-71 the German cavalry patrols were, as far as
I could ascertain, quite unable to penetrate into the wood of Orleans
and that at Marchenoir. These woods, by their mere existence, formed an
effective screen.
To utilise woods for this purpose it will be necessary, according
to the circumstances, the depth and nature of the wood, to post the
fighting detachments of the screening line either at the exit of the
defile on the enemy's side or more towards the defender's side on
the inner edge of the wood, if they can there find a good field of
fire. In any case the opposite edge of the wood should be occupied
by observation-posts; in order, in the first case, to get knowledge
of and to neutralise any hostile patrol which may, in spite of all
difficulties, have penetrated the wood, as soon as they emerge; and,
in the second, to get early information of the entrance of hostile
detachments into the wood, and to be able to hinder, report, and
observe their further advance.
I think that penetration of such a screen is generally considered to
be easier than it really is, especially if the defending cavalry is
supported by cyclists, machine-guns, and even artillery. According
to my opinion, reconnoitring squadrons would only, under favourable
circumstances, be able to break through such a line that has been well
disposed, and, even if successful in so doing, would find it even more
difficult to return. It should never be forgotten that to overcome
well-placed posts, defending themselves with fire action, requires a
great superiority of force; that a squadron can only overcome quite
weak detachments so placed, and will, if successful, very soon find
itself confronted by a superior force of the enemy's reserves. Single
patrols of picked scouts may perhaps creep through, but their return
will be problematical unless they are strongly supported from the rear.
It will therefore generally require strong forces of the army cavalry
to break through a well-organised screening line composed of moderately
strong cavalry detachments, and to maintain the breach so made long
enough to carry out the object of the reconnaissance. The place where
the screen is broken must in all cases, even where the main body of the
victorious reconnoitring cavalry is obliged to advance farther, be so
strongly occupied that it will under all circumstances remain open for
the service of transmission and for the eventual retirement.
The greater the advantages of a defensive screen, the more must the
divisional cavalry naturally endeavour to avail itself of it, in
order to compensate in some measure for its numerical weakness. It
will always seek, even during the advance of the army, to choose such
favourable areas for an occasional halt, and to reach them by advancing
in _bonds successifs_. Such procedure will facilitate at the same time
the carrying out of its duties of screening and of warding off hostile
detachments by defensive action. In order to secure the greatest
possible effect for such action a similar procedure as regards time and
space must be arranged with the cavalry of neighbouring columns, or
ordered by superior authority.
During the night, when it is not possible to occupy advanced areas,
the divisional cavalry should try to assist the screen by being so
disposed that detached posts will lie on the main road in advance of
the infantry outposts and at crossroads and defiles, with a view to
capturing the enemy's patrols. The erection of temporary obstacles,
particularly of wire, will considerably assist this action. In
friendly country the inhabitants will be able to co-operate in this,
and, by judicious conduct and the procuring of timely and sufficient
intelligence, may be of great use to the force. In erecting such
obstacles it must always be remembered that our own advanced patrols
should be warned of them, or that by some kind of prearranged mark upon
the road they should be made aware of their presence when returning
with reports through their own line. It scarcely needs to be emphasised
that such measures should be made use of by the army cavalry as well
as by the divisional cavalry, in order to increase their own safety at
night.