He must arrange for the reorganisation of his victorious forces and for the pursuit and complete overthrow of the enemy.
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PROTECTION AND RECONNAISSANCE
"Surprise consists in the hard fact that the enemy suddenly appears in considerable numbers without his presence having been known to be so near for want of information; and without it being possible to assemble against him for want of protection."—MARSHAL FOCH.
Every commander of a force, however large or small, is responsible for the protection of his command against surprise, and a force can only be regarded as secure from surprise when protection is furnished in every direction from which interference is possible. Detachments are therefore provided by every commander, their duty being to warn him if hostile forces are discovered in the vicinity of such forces, and to gain time, at all risks and at any sacrifice, for the commander of the troops they protect to carry out his plans unimpeded by the enemy. "A mission of protection does not necessarily imply a defensive attitude, it will often be better performed by an offensive" (Marshal Foch). There is the closest connection between Reconnaissance and Protection. It is only by finding out the location, strength and movements of the enemy that a commander can decide how best to protect his troops, and the forces he employs to protect his troops against surprise will very largely prevent the enemy finding out his own strength and dispositions. Detailed and timely information about the enemy and the theatre of operations is a necessary factor in War and the value of the information depends on whether it can reach the authorities in time to be of use.
Facilities for reconnaissance have been enormously increased by the introduction of man-carrying, self-propelled Aircraft. Before their introduction reconnaissance {99} at a distance from the forward troops was limited by the speed and endurance of the cavalryman's horse, and by the skill of the cavalry scout in penetrating the preventive screen of hostile cavalry, and in escaping the net spread out to catch him on the return journey. His radius of operations was comparatively small, that of the aërial observer is practically unlimited, as his machine will carry him over the hostile area, and unless he is driven down by opposing aircraft, or crippled by defensive fire from the ground, he returns in a comparatively short space of time to his base, with his budget of news, and may bring with him a series of photographs.
POSITION WARFARE.—When opposing forces are entrenched at no great distance from one another, photographs taken from the air lead to the discovery of new works from which the intentions of the enemy can be predicted. On the Western Front in the Great War, photographs taken from the air revealed the construction in the German training area of actual sectors of British trenches in facsimile, thus indicating the rehearsal of an attack on a definite part of the line. Hostile aircraft are prevented from carrying out similar observational journeys, the resistance of defending squadrons is overcome, and whenever a favourable target is presented, casualties are caused by bullets and bombs. Observers report all suspicious movements and changes in trench construction, and from photographs taken at daily intervals maps of hostile trenches are constructed and revised. Infantry patrols and raiding parties are sent out by night and by day, and information is gleaned from the uniforms and badges of captured prisoners as to the distribution of hostile troops, while changes in the plan of trenches, in the siting of wire entanglements, or in the emplacements of guns and mortars are duly noted. In addition, troops in observation posts, in or ahead of the front line, in favourable and unsuspected {100} localities, are constantly observing the enemy, and sentries over all posts containing troops are ready at all times of the day and night to alarm the local garrisons. Resistance is afforded by a series of mutually supporting strong points, sufficiently garrisoned by troops who guard against surprise and hold their ground against attack. Entrenchments, with dug-outs and shelters, provide protection from fire, and barbed wire entanglements prevent unbroken rushes by the enemy, and entice him into openings that are swept by rifle and machine-gun fire. Box respirators and other appliances nullify the effects of gas, and camouflage disguises the position of trenches, troops, guns, and dumps, and so screens them from observation and direct bombardment, while it provides unsuspected means of observing the enemy's movements.
MANOEUVRE WARFARE.—In a War of Manoeuvre the steps taken to obtain security against surprise vary with the situation of the troops. Hostile aircraft flying high from the ground are dealt with by counter-attack by armed aeroplanes, but as aërial fighting requires space for manoeuvre hostile machines flying within 3,000 feet of the ground must be dealt with by machine gun, Lewis gun, or concentrated rifle fire, except in cases where it is essential to conceal from the enemy that a certain position or locality is occupied, and where the troops are so well hidden as to escape detection unless they open fire. Movement is easily detected by low-flying aeroplanes, and in fair weather troops can be recognised as hostile or friendly by an observer at 500 feet, while movements of formed bodies on a road are visible at 5,000 feet. Troops remaining stationary in shaded places may easily escape observation, and if small bodies in irregular formation lie face downwards they are difficult to detect, even in the open. When a force is in movement, detachments move with it to afford protection in every direction from which interference {101} is possible; and when a force is at rest, detachments with similar duties secure it from disturbance and keep off attack until it can be met or developed without disadvantage. These phases are dealt with under the headings of "THE ADVANCED GUARD," "FLANK ATTACKS AND FLANK GUARDS," "THE REAR GUARD," and "OUTPOSTS."
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