THE PLATOON.--The smallest unit which can be divided into independent bodies, each capable of Fire and Movement, is the platoon, the four sections of which can pin the enemy to his position by fire and can manoeuvre round his flanks. The normal distribution of the platoon for the Attack is either the Square or the Diamond Formation. In the _Square Formation_, two sections are forward covering the frontage allotted to the platoon, and the remaining two sections are in support, in such formation as may keep them in readiness for instant manoeuvre with due regard to the avoidance of unnecessary loss. In the _Diamond Formation_, one section leads to reconnoitre and to pin down the enemy, while the remaining three sections are held in readiness to manoeuvre for the decisive attack at the point in the enemy's defence which offers the best prospect of success. The Diamond Formation is that best suited to an Attack in an Encounter Battle, when the nature of the enemy's dispositions are imperfectly known. It possesses the great advantage of preserving {71} the power of manoeuvre for three-quarters of the platoon until the action of the leading section has developed the situation.

In each case (except when the Attack is launched against a highly organised defensive position), the forward sections will be preceded by _Ground Scouts_, to find the most covered line of advance and the best fire positions, and to guard against ambush. These Ground Scouts advance until checked, when they remain in observation until joined by the leading sections. During the early stages of the Attack in an Encounter Battle _Flank Scouts_ may be required until such time as the deployment of the platoon renders them unnecessary.

Against a highly organised defensive system platoons may not be able to advance to the Attack without a barrage, and it is essential that all movements should conform exactly to the timing of the barrage and that the troops should keep under the back edge of the shrapnel curtain, so as to deliver their a.s.sault before the enemy has time to bring rifles and machine guns into play. Under such circ.u.mstances, Ground scouts must be dispensed with. Such a position will not be attacked without careful previous reconnaissance and the lines of advance will have been chosen beforehand. The Square Formation will be that usually adopted for attacks on highly organised defensive positions, with the two rifle sections forward and the two Lewis-gun sections in support. The Lewis-gun sections are thus able to protect the flanks of the rifle sections, and to deal with isolated enemy machine guns, or concealed bodies of riflemen, which might come into action with reverse or enfilade fire after the forward sections have pa.s.sed over the occupied ground.

THE PLATOON COMMANDER.--The platoon commander must explain the situation to his subordinates and point out the line of advance. He should usually move with the forward sections during the preparatory {72} phase of an Attack, and when the forward sections have been committed to the Attack he should a.s.sume control of the supporting sections and move with them. If his platoon is in support, he will thus be with the forward sections before the platoon is involved in the fight. The success of Infantry in the Attack depends not only on dash, control, and leading, but upon the intelligent co-operation of support commanders, who must keep themselves acquainted with the course of the battle by intelligent observation and will thus possess an "appreciation of the situation" before involving their men in action, and can direct the supports to the right spot at the right time, to influence the battle by fire and by movement, without hesitation or delay.

THE COMPANY.--The normal distribution of the company, when acting with other companies of the battalion, is two platoons forward and two in support. To meet the expectation of a stubborn resistance, or to cover an unusually extensive frontage, three platoons may be forward, with one in support; and where information as to the enemy's dispositions is lacking, but strong opposition is unlikely, one platoon may be forward with three in support, thus enabling the company commander to use any or all the supports to influence the attack on obtaining information as to the point in the enemy's position which offers the best prospect of success. When the frontage allotted to a company is above the normal, the leading platoons should not endeavour to cover the whole front, but gaps should be left between them; otherwise the men will be so widely extended as to deprive the leaders of the power of control.

When a company is acting independently, the normal formation will be two platoons forward, with one in support, and one in reserve.

THE COMPANY COMMANDER.--The company commander will allot the tasks and the frontages of his {73} platoons and give orders as to their distribution, and must state where he will be himself during the Attack. His position will be determined by the necessity of keeping informed throughout the Attack of the situation and of the progress of his platoons, and he is responsible that all essential information on these points is pa.s.sed back to the battalion commander. He must also keep in touch with companies on his flanks, sending out patrols for this purpose, if necessary; and must use every opportunity afforded by the fire or smoke provided by other units or arms to get forward or round the enemy's flanks. He will use his supporting platoons to push through where the resistance is weak in order to turn the flank of those portions of the enemy which are holding up the advance. As soon as this temporary phase has been brought to a successful conclusion the company commander must reorganise his platoons and secure their advance on the objective. When the objective has been gained the position must be consolidated and patrols sent out to prevent surprise.

THE BATTALION.--The distribution of the battalion depends entirely upon the nature of the task allotted to it. Where the enemy's dispositions are known and considerable resistance is antic.i.p.ated in the earlier stages of the Attack, the battalion will normally be distributed with two companies forward, one in support and one in reserve. The forward body should thus be strong enough to develop the Attack to such a point that a decisive blow can be delivered by the supports against the main resistance, and the reserve company is in hand for the completing stages of the action or for stabilising the local battle. Where the enemy's dispositions and the degree of resistance are still the subject of conjecture, one company only may be forward, with two in support, so that the main strength of the battalion will not be committed to any definite _role_ before it is needed and before the situation of the enemy is discovered.

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THE BATTALION COMMANDER.--"The powers of personal control of a battalion commander upon the field of battle are limited, and success will depend, in a great measure, on the clearness of the orders which commit his leading companies to the Attack" ("Infantry Training, 1921"). The battalion commander should be supplied with any details concerning the enemy and of co-operating troops. He must understand his objective, the limits of his frontage, and the extent of help which he will receive from the other arms. In addition to such information as is supplied regarding the enemy's strength and dispositions, particularly with regard to wire (or other obstacles) and machine guns, he must ascertain the best positions of a.s.sembly for his companies, the best lines of approach to the objective, the most covered line of advance for his supports and reserves, and the best position for his own headquarters during each stage of the Attack. In his orders for the Attack he will reveal all information concerning the movements and dispositions of the enemy and of co-operating troops and arms; he will allot tasks to the companies and to the machine-gun platoon (if not brigaded) and will define the frontage of the forward companies; he will also detail the a.s.sembly positions, give compa.s.s-bearings for the advance, describe the action of other arms in support, make the necessary signalling arrangements, notify the zero hour, arrange for the synchronisation of watches, notify his own position before, during, and after the Attack, and indicate the point to which reports are to be sent, notify the medical arrangements, and issue instructions as to the collection of stragglers, the escort and destination of prisoners, the supply of ammunition, and the equipment to be worn. The quartermaster will receive orders as to the bringing up of rations during the battle.

Before issuing to the Attack a proportion of officers and other ranks will be detailed to remain behind, to replace casualties when the engagement is over.

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The position of the battalion commander will be chosen with a view to keeping in touch with the progress of the Attack in all its stages and of influencing the fight by means of the reserves. Personal control is difficult to exercise once troops are committed to the fight, but opportunities for rapid decision were frequently offered to battalion commanders in the Great War, and seized with a success which transformed a check into a victory. In 1916 a battalion commander of the Coldstream Guards, seeing his command disorganised by fire and resistance, by personal example rallied and reorganised the waves of the Attack and added the necessary momentum to the a.s.sault, which then reached its objective. On April 14, 1917, the commander of a battalion of the Royal Newfoundland Regiment witnessed the launching of a local counter-attack by the Germans on the village of _Monchy-le-Preux_, and by a rapid advance with the fighting portion of his headquarters, staved off the attack until the arrival of reinforcements from the 88th Brigade enabled it to be driven back in disorder. On November 30, 1917, during the German counter-attack from Fontaine Notre Dame to Tadpole Copse, in the Northern Sector of the _Cambrai_ zone, the Germans forced their way into our foremost positions, and opened a gap between the 1/6th and 1/15th London Regiments. Local counter-attacks led by the two battalion commanders with all available men, including the personnel of their respective headquarters, once more restored the situation. In March, 1918, during the most critical period of the German thrust at Amiens, a battalion commander of the Border Regiment again and again, on horseback and on foot, personally restored the situation.

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DEFENSIVE ACTION

"The soul of the Defence is the Counter-Attack."--MARSHAL FOCH.

Defensive action may be initiated by a commander in the field, or it may be imposed upon him by the enemy, and a commander may rely upon fortification to a.s.sist him in defeating the enemy, or he may employ manoeuvre to effect or to postpone a decision.

A commander may desire to pin the enemy to an attack upon a fortified position, garrisoned by a portion only of his force, while he detaches another (and probably greater) portion to attack the enemy from an unexpected quarter. An outstanding example of this form of action is exhibited in the _Battle of Chancellorsville_ (May 2-3, 1863), where Lee kept at bay Hooker's army of 90,000 with one-third of his force and detached Stonewall Jackson with 30,000 men to attack the Federal rear.

Action of this kind is peculiarly effective, but it requires a secrecy which modern aircraft would almost certainly unveil, and if the manoeuvre failed to escape observation it would probably result in disaster both to the retaining force and to the detached troops.

A different form of the combination of defence with manoeuvre is the Defensive-Offensive battle, with examples of which the history of Warfare is amply supplied--Marengo, Austerlitz, and Waterloo being typical battles of this nature. In this form of defensive action a commander invites the enemy to attack a well-chosen position, and after exhausting the enemy's strength and holding up the a.s.sault, the commander pa.s.ses from the guard to the thrust and overwhelms {77} the exhausted foe by an irresistible and sustained counter-attack with all the means at his disposal.

A position is sometimes occupied as a matter of necessity, sometimes merely as a matter of tactical prudence. At _Nachod_ (June 27, 1866) the Prussian Advanced Guard hurriedly established a defensive position and kept at bay the whole Austrian Army, while the Prussian Army emerged in security from a defile and manoeuvred into battle array.

The _Pa.s.s of Thermopylae_ was occupied in B.C. 480 by 1,400 Greeks under Leonidas, King of Sparta, to withstand the Persian hosts of Xerxes, and although the Greek force was destroyed by an attack from the rear (through the disclosure of a secret path by a renegade in the Persian service), the resistance offered to the "invincible" Persians emboldened the Greeks in their future encounters, and led to the ultimate defeat of the invaders. According to the legendary history of Rome, Horatius Cocles and two companions defended the _Sublician Bridge_ over the Tiber against Lars Porsena and the whole army of the Etruscans. This legendary heroism was equalled or surpa.s.sed during the _Second Battle of the Somme_ (March 21, 1918). "The bridges across the Crozat and Somme Ca.n.a.ls were destroyed, though in some cases not with entire success, it being probable that certain of them were still practicable for infantry. Instances of great bravery occurred in the destruction of these bridges. In one case, when the electrical connection for firing the demolition charge had failed, the officer responsible for the destruction of the bridge personally lit the instantaneous fuse and blew up the bridge. By extraordinary good fortune he was not killed" (Sir D. Haig's Dispatches). At _Rorke's Drift_ (January 22, 1879) a force of 80 other ranks of the 24th Regiment, under Lieutenants Chard and Bromhead, with about 40 hospital cases, drove off the repeated attacks of 4,000 Zulus, part of Cetewayo's army which had surprised and annihilated the garrison {78} at _Isandhlwana_ earlier the same day. An astounding feat of arms was performed by a small body of troops during the withdrawal of the British Army in face of the overwhelming German attack at the _Second Battle of the Somme_. A detachment of about 100 officers and men of the 61st Brigade, 20th Division, was detailed to cover the withdrawal of their division at _Le Quesnoy_ (March 27,1918). Under the command of their Brigade-Major (Captain E. P. Combe, M.C.) the detachment successfully held the enemy at bay from early morning until 6 p.m., when the eleven survivors withdrew under orders, having accomplished their task.

There are many instances of the occupation of an area for an actual or potential tactical purpose. Before the _Battle of Salamanca_ (July 22, 1812) a Spanish force had been detached by Wellington to cover a ford of the River Tormes by occupying the castle of Alba de Tormes, but the force was withdrawn without Wellington's knowledge, and Marmont's defeated army retired unmolested over the ford to the fortress of Valladolid. In the campaign of 1814, Napoleon placed a garrison of 1,200 in the _Fortress of Soissons_, but on March 3,1814, the garrison capitulated without exhausting all the means of defence as the regulations of War ordain, and the bridge at Soissons enabled Blucher and Bulow to unite their forces across the River Aisne. In the Waterloo campaign, Wellington stationed 17,000 men at _Hal_ and _Tubize_, 8 miles from his right on the field of battle at Waterloo, to repel a possible turning movement and to form a rallying point if his centre was broken, and with 67,000 men took up a position astride the Nivelle-Brussels and Charleroi-Brussels roads which met at Mont St.

Jean. He was deprived of the services of this detachment and modern criticism has been directed against this disposition of his forces. It is, however, permissible to suggest that the security of his right flank, and the possession of a rallying point, inspired him with the confidence which enabled him to {79} withstand the sustained attacks of Napoleon until the arrival of Blucher's corps permitted him to overwhelm his adversary.

A further form of defensive action is the occupation of a series of extemporised positions and the orderly withdrawal to a further series before the actual a.s.sault of the enemy, resistance being combined with manoeuvre for the purpose of delaying the enemy's advance or of holding up his pursuit. Delaying action of this kind is commonly employed in rearguard fighting, when the object to be gained is time rather than position, and the offensive action of the defender is limited to local counter-attacks at favourable or desperate moments. But the guiding principle in all defensive operations, including delaying action, must be that "when an enemy has liberty of manoeuvre, the pa.s.sive occupation of a position, however strong, can rarely be justified, and always involves the risk of crushing defeat" ("Field Service Regulations,"

vol. ii. (1920)).

THE OFFENSIVE SPIRIT.--Although there are many forms of defensive action the soul of the Defence in every case is a vigorous offensive spirit. In the Active Defence, the Decisive Counter-Attack, ending in the overthrow of the enemy, is the manoeuvre originally in view when the defensive _role_ is adopted. In the Pa.s.sive Defence against superior numbers. Local Counter-Attacks end with the recapture of a tactical point or the repulse of a determined a.s.sault, and in the Delaying Action they overwhelm by surprise fire or a.s.sault a detached force which has advanced with such rapidity as to enable the defenders, without undue risk, to cut off and annihilate the isolated enemy body.

Whatever the tactical situation, it is by the vigour of the offensive spirit alone that success may be achieved in the face of a determined enemy.

MODERN WARFARE.--In modern warfare the defensive position plays a part of increasing importance, owing {80} to the great power conferred on the defence by modern armaments. "Machine guns and barbed wire permit the rapid organisation of defensive points of a value which cannot be disputed. In particular, they have given to a trench, or to a natural obstacle, a solidity which permits a front to be extended in a manner unsuspected before this war; they permit the prompt consolidation of a large system that is easy to hold" (Marshal Foch). "The modern rifle and machine gun add tenfold to the relative power of the Defence as against the Attack. It has thus become a practical operation to place the heaviest artillery in position close behind the infantry fighting line, not only owing to the mobility afforded by motor traction but also because the old dread of losing the guns before they could be got away no longer exists" (Marshal French). It is thus possible to hold the forward positions of a highly organised defensive system with a minimum of exposure to loss, the extra strength of the position counterbalancing the reduction in numbers, but a preference for defensive action of this kind may generally be regarded as an admission that a victorious outcome of the campaign is not antic.i.p.ated at the time of its adoption in the theatre in which it is employed. "It is of paramount importance that in those parts of a theatre of operations where a commander aims at decision a war of movement must never be allowed to lapse into position warfare so long as a further advance is possible. Position warfare can never of itself achieve victory"

("Field Service Regulations," vol. ii. (1920)). However strong entrenchments may be they will not defeat the adversary's main armies, nor can they withstand indefinitely the attacks of a determined and well-armed enemy. It is scarcely even probable that an army behind entrenchments can by that means alone inflict such losses on its a.s.sailants as will enable the initiative, or liberty of manoeuvre, to be regained and the a.s.sailant's main armies to be defeated. The operations on both sides {81} are in the nature of a siege, and however prolonged the siege, the advantage will be gained in the long run by superiority of aggressive action in the air and over and under the ground. In addition to the absence of opportunity for the grand offensive there are two further points of difference between defensive action in Position Warfare and the defence in a War of Manoeuvre. The first of these is the inevitable absence of flanks to be a.s.sailed, as the operations necessitate a connected line of strong points from sea to sea, or from the sea to the impa.s.sable barrier of neutral territory.

Mounted troops are therefore doomed to inaction in their most important sphere, until the lines have been breached and the enemy is forced to retreat, and the opportunities for delivering flank attacks are meanwhile confined to the infantry, and will be due to irregularities in the alignment of the strong points, upon which enfilade fire may be brought to bear. The second point of difference is the abundance of time at the disposal of commanders for developing and rehearsing elaborate systems of attack and defence, and for obtaining detailed plans of the hostile works, through continuous reconnaissance by the Air Service. In most countries there must be, of necessity, a prolonged period of inactivity on both sides in a Position War, owing to the severity of winter conditions, or to the occurrence of the rainy season, and during that period it will seldom be possible to penetrate the enemy's main defences on such a scale as to bring about the grand offensive. But this is a period of inactivity in appearance rather than in fact, for no defensive system is ever perfect, no strong point but needs further consolidation, new trenches are constantly constructed or improved, and fresh areas are covered with wire entanglements. Guns of all calibres, underground mines and light mortars are ever at work, demolishing, wounding, and killing, while lachrymatory and asphyxiating sh.e.l.l-fire is to be expected at all times. On a smaller scale, snipers on both sides have a daily bag, and {82} observers are ever at their posts noting every change, however insignificant, and every new piece of work; "listening posts" are detecting hostile plans, while patrols are collecting information and raiding parties are reconnoitring, destroying defences, and inflicting losses, it being the first principle of a raid that it should result in greater losses to the enemy than to the troops which carry it out.

ENTRENCHMENTS.--Entrenchments have been employed in the defence from the earliest times. The Roman walls in Britain, the Great Wall of China, the earthworks in the Russian War of 1854-1855, in the American Civil War of 1861-1864, in the Russo-Turkish War of 1878, and the Russo-j.a.panese War of 1904-1905 are notable examples. But in no war previous to that of 1914-1918 have they played so important a part.

One of the most famous series of entrenchments in previous wars were those constructed in 1810 by Colonel R. Fletcher, of the Royal Engineers, at _Torres Vedras_. These fortifications extended for 50 miles and contained 126 closed works, mounting 247 guns, and behind these lines Wellington ama.s.sed stores and reinforcements until the retreat of Ma.s.sena enabled him to resume the initiative. In front of these lines everything that could support the French armies had been removed; behind them Wellington's forces were well provided in every respect. On October 10, 1810, Ma.s.sena was confronted by the entrenchments, the existence of which had been kept a profound secret, while their strength prevented them from being carried by a.s.sault.

Before the end of October a Portuguese spy wrote to Wellington: "Heaven forgive me if I wrong the French in believing they have eaten my cat"

(Napier). During the night of November 14-15, Ma.s.sena broke up his camp and withdrew. But it was not the lines of Torres Vedras which won back the Peninsula. Spain and Portugal were saved by the bold march northwards {83} to Vittoria. "In six weeks Wellington marched, with 100,000 men, 600 miles, pa.s.sed six great rivers, gained one decisive battle, invested two fortresses, and drove 120,000 veteran French troops from Spain" (Napier).

DEFENSIVE SYSTEMS.--"Whether it is the intention of the commander to resume the offensive at an early date or whether it is likely that the defensive system will be occupied for a considerable period, the principles on which the construction of all defences should be undertaken are the same. All defensive systems should be planned from the outset in such a way that they can easily be adapted to the requirements of a prolonged defence. The ground must be thoroughly reconnoitred and should at the first be divided into a series of tactical posts and defended localities. These posts should be self-supporting, but should be so sited that the garrisons mutually support each other by fire. The gaps between the posts must be covered by the fire of the garrison of the posts, and machine guns may also be sited to bring fire to bear from positions in rear and to the flanks"

("Infantry Training, 1921"). This principle must govern the choice of the position to be defended as well as the organisation of the position for defence, and troops detailed for the defence of an area must continue to improve the defensive arrangements in that area until such time as the offensive is resumed.

CHOOSING A POSITION.--The framework of the modern defence consists of artillery and machine guns; into this framework are fitted the defence posts or defended localities garrisoned by infantry, who are responsible for holding their ground at all costs and for inflicting the greatest possible loss on the enemy. A commander will require a position which affords elasticity for increasing the resistance as the attackers penetrate the defences, and depth will thus be essential. He will require a position wide enough to prevent the whole of his front being masked by a retaining attack of a part of the {84} enemy's forces while a strong flank attack is simultaneously delivered; and in a War of Manoeuvre he will require facilities for the Decisive Counter-Attack.

The depth of the position will develop automatically in a War of Position, but it must always be sufficient to enable troops to a.s.semble in rear of the forward position before moving up and to afford rest to troops when withdrawn from the front line. The width of the position will generally depend upon the strength of the defending force, the guiding principle being to keep about half the force in General Reserve; if, therefore, the remainder of the force is insufficient for the purpose of holding the defences the position is too wide for the tactical requirements of the Active Defence. In Position Warfare, however, a defensive system must necessarily be extended beyond the limits that are practicable in the Active Defence, and the numbers available for the garrison are supplemented by denying ground to the attack by means of obstacles, the removal of which is prevented by machine-gun and rifle fire.

THE OUTPOST ZONE.--For the Active Defence of a position the defensive system will consist of an Outpost Zone and a Battle Position. The Outpost Zone is garrisoned by a protective force which keeps a constant watch on the enemy and absorbs the first shock of the attack, watch being kept by means of well-concealed sentry posts on the Line of Observation, supported by a chain of small self-contained defensive posts, while resistance is offered by a series of self-contained, mutually supporting defence posts on the Outpost Line of Resistance.

THE BATTLE POSITION.--The Battle Position will be established in the area in which the commander decides to fight out the battle and break the enemy's attack. It therefore forms the keystone of the whole defensive position and must be organised in depth to afford elasticity for defensive action. "In principle, in order to protect {85} the battle position from being obliterated by a preliminary bombardment, it should be beyond effective range of the enemy's mortars" ("Field Service Regulations," vol. ii. (1920)).

THE SEMI-PERMANENT SYSTEM.--When a campaign is prolonged in any area without decisive results a War of Position may be developed by one or both of the combatants. In such cases the Outpost Zone is developed into an intricate trench system, with protective avenues leading from front to rear and with deep dugouts to protect the garrison from artillery fire. The Battle Position will probably coincide with the Outpost Zone, the trenches being used for the purposes of observation until the fire positions are manned to resist an a.s.sault.

In parts of the line on the Western Front of the Great War, "Pill-box"

forts, constructed of concrete, took the place of continuous lines of trenches. These machine-gun forts were garrisoned, according to size, by groups from 5 to 50 strong, and were echeloned in plan, to sweep all approaches, and together to command with their mutually supporting fire the whole area over which they were spread, the intervening ground being entangled with wire so placed as to invite attacking troops into places where flanking fire may be poured into them. The advantages of the pill-box system over the continuous line of strong points are princ.i.p.ally defensive. Fewer men are required for them than for the trench systems, and there is less liability of loss from artillery fire. But there are certain grave disadvantages. Well-directed artillery fire is liable to destroy some of the pill boxes, and a direct hit from a heavy gun will possibly put a larger fort out of action, thus crippling the defence by the removal of a peg on which the whole scheme depends. Supports and reserves are necessarily far in rear and must be brought up through the open to repel successful attacks, while a defensive scheme {86} composed entirely on the pill-box plan is less suitable for aggressive action than entrenchments, there being fewer facilities for a.s.sembling troops prior to the attack.

COMMON CHARACTERISTICS.--Whatever the system of defence or phase of warfare, every commander must guard his flanks and keep in touch with neighbouring units. He must always be ready to a.s.sist a neighbouring commander by enfilade fire or by a relieving counter-attack; or to throw back a defensive flank in the event of a neighbouring post being captured by the enemy. Each post, occupied for the Defence (except in Delaying Actions, where manoeuvre takes the place of a settled resistance), forms a self-contained centre of resistance, capable of all-round fire, and the duty of the garrison is to defend the area allotted to it to the last man and the last round.

THE ACTIVE DEFENCE.--The Active Defence may be considered according to the reason which prompted the commander of the force to occupy the position. It may have been deliberately chosen as a position which the enemy must attack, and in the hope of delivering during that attack a crushing and decisive counter-blow; or it may have been chosen of necessity, to meet an attack by deployment on the ground of the encounter, with the same hope of delivering a decisive counter-stroke when the opportunity arrives.

There is little difference in the steps to be taken by the commander, as in the first case a General Reserve is specially detailed for the counter-stroke; and in the second, the position will be held with as few troops as the tactical situation permits, in order to provide as large a General Reserve as possible for the Grand Offensive. A commander will be influenced by many considerations in his choice of a defensive position:--

(i) _The position must suit the plan of operations_; it must be "in the enemy's way," and this the commander must be able to judge from the map. It is {87} to be noted that to bar the enemy's way it is not always essential to get astride his lines of advance, as a position on parallel lines, threatening his flank and rear, cannot be ignored by the enemy, unless he is strong enough to detach a part of his force to mask the defender's position, while he proceeds to his objective with his main army. "It was a mistake to a.s.sume that in order to cover Turin one had to stand astride the road leading to that town; the armies united at Dego would have covered Turin, because they would have stood on the flank of the road leading to that town" (Napoleon).

(ii) _The position must not be too extensive_ for the troops at the disposal of the commander, and this will be governed by the extent of the line to be actually held. It will consist of a series of mutually supporting tactical points, which can be held as "pivots on which to hinge the defence of the position," and the object must be to obtain the maximum of fire effect on all ground over which the enemy can advance with the minimum of exposure to his fire. A rough-and-ready rule is that unless one rifle per yard of the frontage occupied can be supplied by the "troops to hold the position" (which should not exceed one-half the available force) then the position is too extensive and should be narrowed. On the other hand, too narrow a front may enable the enemy to develop, early in the engagement, strong flank attacks, which may make the position untenable before the time is ripe for the a.s.sumption of the offensive. The _Conde-Mons-Binche_ line held on August 22-23, 1914, by Sir J. French's army (I. Corps, General Sir D.

Haig; II. Corps, General Sir H. L. Smith-Dorrien) had a total width of 25 miles, and the troops at disposal, including General Sir E. H. H.

Allenby's Cavalry Division, consisted of about 75,000 all arms. The frontage actually held did not exhaust half this force at the rate of one rifle per yard, and a position in rear had also been selected, between Jerlain and Maubeuge, with a frontage of 15 miles. The _Retreat from Mons_ was {88} due not to the excessive width of frontage, but to the success of the German attack on the French V.

Corps at Charleroi (August 23, 1914), which left the right flank of the British Army "in the air," while two German Corps were working round the left flank. The British III. Corps (General Sir W. P. Pulteney) did not arrive until the retreat was in full swing. At the _First Battle of Ypres_ (October 31, 1914) many parts of the line were held with one rifle for 17 yards, and there were no Supports or Local or General Reserves. Yet the line was not only maintained but a counter-attack at Gheluvelt thrust the attacking Germans behind their entrenchments.

(iii) _There must be a clear field of fire_ to prevent the enemy approaching unmolested within effective range, and particularly within close range, from which the enemy will endeavour to establish an ascendency in the fire-fight.

(iv) _The flanks must be secure_, or at least as strong as possible. A flank resting on a deep river or a marsh may be regarded as secure, and a flank extending to the sea, or to the boundary of a neutral State. A flank on high ground which commands all approaches and provides means of distant observation may be called strong. It is a great advantage if one flank can be posted so strongly as to compel the enemy to make his main attack on the other, as this will enable the defender to forecast the direction of the decisive attack and to dispose his General Reserve to meet and overwhelm it.

(v) _There should be facilities for cover_ on the position and concealed avenues of approach from the rear. A crest affords cover on the reverse slopes and woods provide concealment, while time enables artificial means to be adopted. Tactical cover can be provided by cavalry and advanced troops in the early stages of manoeuvre-battle, and in removing this cover the troops can withdraw in such a way as to lure the enemy on {89} to a false position. They can also induce premature deployments by the enemy, and movements across the front of the real position.