The "Field Service Manual" sums up, I think, the chief considerations as regards screening, for the most[Pg 92] 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,[Pg 93] 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[Pg 94] 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 r?le 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. Exten[Pg 95]sive 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[Pg 96] 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 in[Pg 97]fantry 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.