Chapter 10

"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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THE ADVANCED GUARD

"Fabius, the saviour of Rome, used to say that a commander could not make a more disgraceful excuse than to plead, 'I never expected it.' It is, in truth, a most shameful reason for any soldier to urge. Imagine everything, expect everything."--SENECA, "_De Ira._"

Every moving body of troops must be protected by detachments, the force detached to precede the advance being known as an Advanced Guard, and when a body of troops so protected halts, the responsibility for protection during the halts remains with the troops which have been protecting the march until they are relieved, the commander of the Advanced Guard exercising his discretion as to halting at once or moving forward to occupy a position which may be of more tactical advantage.

STRENGTH.--The strength of this Guard depends on the proximity of the enemy, but it must always be strong enough to brush aside slight opposition, so that the advance of the force it is covering may not be delayed by small hostile forces, and to resist the enemy, when encountered in strength, for such time as will enable the force it is covering to prepare to meet or deliver an attack. No general rule as to the numerical strength of an Advanced Guard can be given, as the number of troops required depends almost entirely upon the tactical situation and the country through which the protected force is passing. It should, however, whenever possible be composed of a complete unit or formation under its own commander, and it is found in practice that an Advanced Guard will seldom be less than one-eighth or more than a quarter of the whole {103} force. When a large force is advancing in several columns on parallel roads it will be preceded by a "Strategical Advanced Guard," which protects the front and flanks of all the columns. The "Tactical Advanced Guard" provided by each column may then be reduced in strength.

DISTANCE.--The distance at which it moves ahead of the force it is covering depends upon the nature of the country through which the force is moving, upon the strength of the Main Body, and upon the tactical situation, but it must always be sufficient to enable the Main Body to deploy, to get into battle formation--unmolested by the enemy's artillery, if required to do so. It is clear, therefore, that the larger the Main Body the greater the distance must be, as more time will be required for deployment. The Advanced Guard of a Brigade of infantry, with artillery, would move at a distance of 1 to 2 miles between the Main Guard and the Main Body, with the mounted patrols of the Vanguard 4 to 5 miles ahead of the Main Body. These mounted patrols would discover the presence of an enemy, and with the supports of the Vanguard would feel for his strength and ascertain his dispositions. The Main Guard would either assist in brushing him away or would resist, in the best available position, any attempts to attack the Main Body while the latter formed up for battle.

IN ADVANCES.--Infantry forming part of an Advanced Guard to a force advancing must always act with dash and resolution, but their action must always be regulated by the one motive of complying with the intentions of the commander of the force they are covering. Any action contemplated by the Advanced Guard commander must therefore be considered from the point of view of its effects upon the plans of the commander of the main body, but if these plans are not known, the guiding principle will be _to regulate his action solely in the interests {104} of the force he is covering_, and by driving in the advanced troops of the enemy he will obtain information which will assist his superior in coming to a decision, without interfering with his liberty of action, whereas hesitation and delay may give the initiative to the enemy. For this reason, a wide turning movement by the Advanced Guard troops is seldom possible, as time is thereby lost and the front of the Main Body is uncovered. "The ruling factor should be the discovery of some tactical locality held by the enemy, the capture of which will compel his whole line to fall back. If this point can be discovered the whole energies of the Advanced Guard should be directed against it alone, and elsewhere a defensive attitude should be adopted, to avoid surprise of or interference with the Main Body" (General R. C. B. Haking).

It must always be assumed that the enemy will have taken all the necessary steps to protect himself and to hamper reconnaissance by an adversary. If, therefore, hostile troops are known to be in a certain locality, opposition must be expected before that locality is reached, and study of the map should enable the Advanced Guard commander to determine the approximate neighbourhood in which opposition may be expected.

IN RETREATS.--While it is clear that a force advancing towards the enemy must always be preceded by an Advanced Guard it must not be forgotten that a force withdrawing from the enemy must also be so protected, even when it is moving in or towards friendly territory. Such a force will not only prevent the Main Body being surprised by an energetic enemy, pursuing swiftly and getting round to attack where he is least expected, but will also prevent the Main Body being delayed by obstacles, and can delay the pursuit by preparing bridges, etc., for demolition, which can be completed by the Rear Guard when the Main Body has passed over {105} them. It can also reconnoitre the route to be followed, so that the Main Body can proceed without delay.

TRAINING.--In formulating any scheme for the exercise of troops in Advanced Guard work all officers and other ranks should be made to understand the nature of the scheme, and should be informed (a) whether the force is advancing or retreating, whether it is moving before or after action with the enemy, and whether it is in a friendly or a hostile country; (b) what is known of the enemy; (c) the direction and objective of the march; (d) the general intentions of the commander of the Main Body; and (e) the general instructions issued to the commander of the Advanced Guard. "Unless such exercises are carried out in a practical manner, young officers and inexperienced N.C.O.'s will get the impression that an Advanced Guard consists merely of a procession of small bodies of infantry, strung out at fixed intervals on a single road. It is of the highest importance that the training should be carried out on the lines that would be adopted in action" (G.H.Q. Circular).

TACTICAL PRINCIPLES.--"Speed of advance is the first consideration when not in contact with the enemy. Hence an Advanced Guard will move on a narrow front along roads and other channels of communication, with such distances between advanced and supporting bodies as to avoid possibility of surprise. When in contact with, or in the vicinity of, the enemy, security and speed of advance are equal considerations. Hence the Advanced Guard should move by bounds on a broad fighting front across country" ("Infantry Training, 1921").

Before an Advanced Guard commander moves off in compliance with his instructions he will take certain steps in accordance with these tactical principles. He will divide his troops into two portions, known as the _Vanguard_ and the _Main Guard_, and as the duties of the {106} Vanguard are reconnaissance in general, as well as the protection in particular of the Main Guard, it will contain a large proportion of mobile troops, with infantry for assault and resistance, and engineers for clearing the way through or over obstacles. Aircraft, in advance of the Vanguard, not only increase the area under search and expedite the discovery of the enemy, but prevent surprise and assist the Advanced Guard as a whole by close co-operation in feeling for and fighting the enemy when encountered. "In order to reconnoitre one must compel the enemy to show himself wherever he may be. To this end he has to be attacked until the extent of his position has been clearly defined. But the attack is made with the intention not to bring on an action. The skirmishing lines will advance, but they must be able to disengage themselves at a given moment. Pressure is exercised from a distance without allowing the forces exerting that pressure to become tied up" (Marshal Foch). The duty of the Main Guard is Resistance, that is to say, fighting. It will therefore consist mainly of infantry, with artillery and machine guns, and the troops will move in the order in which they will come into action. The Vanguard will be preceded by scouts, special attention being paid to roads and tracks parallel with the advance. This screen is followed by the remainder of the Vanguard, in collected formation, until it is in contact with or in the vicinity of the enemy, with protection at all times against local surprise. The Main Guard follows, in touch with the Vanguard, and with local protection. Both portions have definite commanders, and the commander of the whole Advanced Guard will probably move with the supports of the Vanguard. The commander will also determine the _relative distances_ between the Vanguard and the Main Guard, these being regulated by the strength of the Advanced Guard, and being based upon the necessity of one part supporting the other. The distance of the {107} Advanced Guard ahead of the Main Body may have been mentioned in the operation orders, but if it is left to the discretion of the Advanced Guard commander he will be guided solely by the interests of the force he is covering, and his decision will be influenced by the nature of the country (whether it is open, or intersected by woods, hedges, sunken roads, etc., which make observation even by aircraft a matter of great difficulty) and by the tactical situation, such distance being chosen as will suit these conditions, while admitting the fulfilment of the objects in view, viz.:--to obtain information concerning the enemy and to prevent hostile reconnaissance; to prevent surprise and delay; and to enable the Main Body to deploy into battle formation without interruption by the enemy's fire.

It is also the duty of the commander to ensure _communication_ between the various parts of the Advanced Guard and between that force and the Main Body, by arranging for mounted orderlies and cyclists, signallers and connecting files, in addition to the contact patrols furnished by the Air Service, and to such telegraphic and telephonic communication as can be provided in the field by the Signals. This is of the first importance, as the action of the commanders of the Advanced Guard and of the Main Body will depend on information received, and not only must information be gained by every available means, but it must also be communicated without delay to all concerned while it is fresh and before it becomes stale. It must also be remembered that negative information (_e.g._ that such and such a village has been thoroughly searched and no trace of the enemy found) is at least of equal value to positive information. The repetition or confirmation of information already sent are also of importance, as it is clearly of value to a commander to know positively that the enemy is still absent, or still present, at a certain time in a certain locality. In the American Civil War, during an encounter battle between {108} advanced troops, the commander of the cavalry of the United States Army held up the Confederate advanced troops. A sharp fight took place at _Sulphur Springs_ (October 12, 1863) and the United States cavalry commander became so absorbed in the battle that he failed to send information to headquarters, and General Meade did not learn that he was in contact with the Army of Northern Virginia until late in the afternoon. In the campaign of _Fredericksburg_, General R. E. Lee, with the Army of Northern Virginia, was confronted by General Burnside, with the Army of the Potomac. On November 15, 1862, a patrol of Confederate cavalry discovered Burnside's troops moving eastwards, and another patrol brought news the same day that gunboats and transports had entered Acguia Creek on the Potomac. These two pieces of information, collected at points 40 miles distant from one another, gave Lee an insight into his opponent's design. Information gained by aircraft on September 4 and 5, 1914, and communicated immediately to General Joffre, led to the discovery of the flank march across the Franco-British front by the German I. Army, and to the decisive counter-attack at the _First Battle of the Marne_ (September 6, 1914).

The Advanced Guard commander must be careful how he becomes seriously engaged, and must avoid any enterprise not strictly in accordance with the known intentions of the commander of the Main Body. The tendency to independent action of this kind, which militates against the success of the best laid plans, was very observable in the early battles of the Franco-Prussian War of 1870-1871. Actions were hastily entered on by Advanced Guards, maintained with varying success by the gradual arrival of reinforcements, and finally concluded with barren results and losses in excess of those inflicted. At the _Battle of Spicheren_ (August 6, 1870) the Advanced Guard of the 14th Prussian Division commenced the battle, which had to {109} be sustained for three hours by 11 battalions against 39. During the next three hours 8 more battalions arrived, and at the conclusion of the battle only 27 battalions and 10 batteries in all had come into action against a whole French Corps, and there were two French Corps within reach of the one engaged. Had these "marched to the sound of the cannon," as Napoleon would have marched, the 14th Prussian Division would have been unable to extricate itself without complete disaster. At the _Battle of Worth_ (August 6, 1870) the Prussian Crown Prince had expressed his intention not to engage the French on that day. Yet the Advanced Guard of the V. Corps brought on a battle into which the Bavarian Corps was perforce drawn. The Crown Prince sent word for the action to be discontinued, but the advanced troops were so seriously involved in the battle that reinforcements had to be sent into action. Although tactically successful the battle was out of accord with the settled plans of the Commander-in-Chief. In the same way the Advanced Guard of the VII. Prussian Corps, contrary to the letter and the spirit of the orders of the commander of the I. Army, precipitated an action at _Colombey_ (August 14, 1870). Other troops were drawn into the fight, and finally the whole of the I. Army was engaged in a battle which its commander not only disapproved but had expressly forbidden. The battle had no tactical or strategical results, and heavy losses were sustained on both sides. "Precipitate action of this kind prevents the troops being engaged in the most advantageous manner. For when a small force is engaged against a larger one it becomes necessary, as reinforcements arrive, to move them up to support some point already hard pressed, and the whole force is thus used up and disseminated, instead of being employed collectively where an effective blow may be struck. Thus the direction of the fight is surrendered to the enemy, as at Spicheren and Colombey. The French positions were so strong that the German {110} reinforcements as they arrived were frittered away in support of troops already engaged, and the state of the latter during the action was frequently very critical. At Colombey the battle resolved itself into a desperate struggle along the front of the French position, where the Prussians made little impression, while their losses considerably exceeded those inflicted on the French" (Clery). It is thus seen that the commander of the Advanced Guard must limit his aggressive action in accordance with his instructions and with the tactical and strategical requirements of the force he is covering. But his action in _protecting_ the Main Body is unfettered by any considerations of prudence, and must ever be vigorous and resolute, any risks being taken that ensure the safety of the Main Body. On the morning of the _Battle of Nachod_ (June 27, 1866) the Advanced Guard of General Steinmetz's V. Corps (of the Army of the Crown Prince of Prussia) was in bivouacs on a plateau, after emerging from a long and narrow defile through which the Main Body must march to the open country beyond. About 8 a.m. the cavalry of the Vanguard was checked by the advanced troops of the VI. Austrian Corps. It was imperative that the Prussian Advanced Guard should hold the plateau until the Main Body had extricated itself from the defile. By the rapid and accurate fire of the infantry and horse artillery, and the co-operation of the cavalry against the Austrian squadrons, the thin line was maintained for more than three hours. Less than 7 battalions of infantry, with 13 squadrons of cavalry and 3 batteries of light artillery, kept in check 21 battalions, 11 squadrons, and 4 batteries. Had the Advanced Guard suffered itself to be driven back on the Main Body in the defile a disaster could scarcely have been avoided, and owing to the steadfast endurance of the Advanced Guard the Main Body was able to drive the Austrian Corps from the field.

ADVANCED GUARD PROBLEMS.--The Advanced Guard commander must be able to appreciate without delay {111} the situation which confronts his force, and to solve the problem before him with regard solely to the interests of the force he is covering.