Part 9
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 assault.
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 principally 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 assembling 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 assist 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 assume 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 assumption of the offensive. The _Condé-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.
(vi) _There should be good artillery positions_ to provide effective fire on all hostile avenues of approach, and counter-battery work on hostile artillery positions. There should also be firm ground and good roads for the movement of guns, and an absence of landmarks for the enemy to range on. Guns of the heaviest calibre take part in all modern battles, their disposition being settled in conference with the artillery commander. A battery of field artillery requires 100 yards frontage for its six guns, and there is usually an interval of 25 yards between batteries.
(vii) _There must be depth_ to allow for the disposal and movement of the Supports and Reserves, and for manoeuvres to recapture the forward defences, or to issue to the counter-attack.
(viii) _There must be good lateral and frontal communication_ in order that any part of the line can be quickly reinforced. A position astride an unfordable stream, or high ridge or deep ravine should therefore be avoided. At the _Battle of Dresden_ (August 26, 1813) the Allies were encamped on the left bank of the Elbe. Their forces were posted on the heights, but the position was cut transversely by a deep ravine, so that the left wing was isolated from the centre and right. This vicious disposition did not escape the penetrating eye of Napoleon, who attacked their isolated wing with superior forces and routed it completely, with the capture of 10,000 prisoners, before any assistance could arrive. The task of creating lateral communications, if none exist, is of the utmost importance, as they enable a commander to achieve the primary object of every military manoeuvre, to meet the enemy with superior forces at the desired point.
(ix) _There should be good lines of withdrawal_, and these should be horizontal, or only slightly oblique, to {90} the main position, and not parallel with the general alignment. This is a point of the first importance, for if the Lines of Communication lead straight to the rear a force that is overwhelmed by the attack can withdraw to selected positions and towards its base, if it can keep the line intact and prevent its flanks being turned. A wide base, with alternative lines of approach, is of the greatest value, and when there is undue risk of the Lines of Communication to a base being intercepted, an alternative base, with lines of withdrawal thereto from the unexposed flank, is an acceptable safeguard, as the defence can be protracted while the withdrawing force concentrates upon the changed base. Such a change of base was effected by Marshal French during the _Retreat from Mons_, and amongst many historical examples may be quoted General McClellan's transfer of the _Army of the Potomac_ from the York to the James River in July, 1862, during the _Seven Days' Battle around Richmond_. General Grant changed his base no fewer than five times during the _Campaign in the Wilderness_ (May, 1864), from Washington to Orange and Alexandria Railroad, then to Fredericksburg on the Rappahannock, then to Port Royal, further east on that river, then to White House on the Pamunkey (a branch of the York River), and finally to the James River. "His army was always well supplied, even his enormous numbers of wounded were carried straight away to the base and thence to Washington, without any difficulty, and he had no obstacles whatever to fight against as regards either feeding his army or keeping up the supply of ammunition" (Henderson). In withdrawing a defeated wing it may even be advantageous to rally the troops at a point distant from the field of battle, and to cause the pursuer, uncertain as to the direction of the retreat, to make detachments which can be overthrown by sudden counter-attacks, or to lure a pursuer from the field where their presence is required, as Grouchy was lured after Napoleon's defeat of the Prussians at Ligny {91} (June 16, 1815). The object of Napoleon's attack on the Allies was the separation of Wellington's Anglo-Belgian force from the Prussian Army under Blücher, and after the defeat of the latter at Ligny the Emperor directed Marshal Grouchy to pursue the Prussians and to drive them eastwards. Grouchy conducted a leisurely pursuit and engaged an insignificant part of the Prussian Army (_The Battle of Wavre_, June 18-19, 1815), while the main body of the Prussians moved westwards and assisted in the overthrow of Napoleon at Waterloo.
(x) _There should be favourable ground and a good line of advance for the Decisive Counter-Attack_. In order, therefore, to overthrow the enemy, a position should not be chosen behind an impassable feature which neither side can cross. At _Ramillies_ (May 23, 1706), one wing of the enemy was posted behind a marsh, where it was both unassailable and unable to attack. Marlborough, therefore, ignored that wing entirely, and bringing his whole force against the remaining wing, won easily a decisive victory. The only occasions when an impassable feature is welcome are in the Passive Defence of a small force against overwhelming odds (as was seen in August, 1914, when the Belgians occupied a position behind the _River Gette_), and in the Delaying Action of a Rear-guard fighting for time for the Main Body to get away. In such cases a Decisive Counter-Attack is not contemplated.
OCCUPATION OF A DEFENSIVE POSITION.--The framework of the _defence_ is provided by artillery and machine-gun fire; the backbone of the _offence_ is the infantry. The Commander will _divide the troops_ into (a) _Troops to hold the position_, and (b) _General Reserve_, the golden rule being to make (a) as small as the tactical situation permits in order that (b) may be as large as possible, and its work absolutely decisive. Under no circumstances {92} should the General Reserve be much below half the available force.
Of these two portions, the _Troops to hold the position_ consist of infantry occupying a series of mutually supporting tactical strong points, not necessarily continuous, and of irregular alignment so as to cover with the defender's fire not only the ground over which the enemy can advance, but the front and flanks of neighbouring strong points. This line will be strengthened, as and when necessary, by throwing in the supports, and it will be assisted at critical moments by the local reserves, which, coming up unseen, will deliver local counter-attacks on the assaulting enemy, and will thus restore the battle at threatened points by relieving the pressure on the front line. Their work completed they will be rallied and withdrawn again into local reserve, and it is highly important that they should be kept well under control, or their successful efforts may be neutralised by local reserves of the attacking force. At _Talavera_ (July 27, 1809) a portion of the British force followed up the repulsed French columns too far, and being in turn broken and driven back, was pursued closely by the enemy and retired in disorder to the position. At the battle of _Fredericksburg_ (December 13, 1862) two brigades emerged from the Confederate position and drove Meade's division of the Army of the Potomac out of their lines. But they rushed on with reckless impetuosity and were finally driven back with heavy loss. Local counter-attacks keep alive an offensive spirit in the defenders, exhaust the enemy's powers, draw his reserves into the battle, and thus prepare the opportunity for the Decisive Counter-Attack. The local reserves of flank sections should usually be echeloned in rear of the flank, which can thus be protected at need by determined counter-attacks on the flank of the enveloping force.
_The General Reserve is for the Decisive Counter-Attack_ and is held for this purpose in the hands of the {93} commander of the whole force, in order that it may be used to crush and overthrow the enemy's main attack. The opportunity for this effort is generally obtained only when the enemy has thrown into action his own General Reserve for the decisive attack, and has received a check. A bold and resolute counter-attack at that moment is bound to achieve a decisive success. But the assumption of the _grand offensive should not be confined to the General Reserve alone_. Commanders of sections of the defence who are permitted by the local situation to do so, must at once join in the decisive counter-attack, unless express orders to the contrary have been received; and any definite success obtained must be the signal for the whole force to press the enemy with the utmost vigour. This opportunity will be fleeting, and there must be no delay in seizing it. Every preparation must therefore be made in anticipation of the opportunity so that a pre-arranged plan may be put into execution. "To initiate a counter-attack on a large scale without due time for preparation, co-ordination, and movement of troops is to court failure, with heavy casualties and resulting demoralisation" ("Field Service Regulations," vol. ii. (1920)).
That the soul of the defence is the counter-attack was shown at the battle of _Spottsylvania_ (May 12, 1864). General Hancock's Corps (from Grant's combined armies) had assaulted and captured part of Lee's entrenchments in the Wilderness of Virginia; 20,000 men had assaulted and captured the Salient, taking 4,000 prisoners; they then pressed forward, and sweeping everything before them, drove a wedge right into the Confederate position. "But Lee, recognising the weakness of the Salient, had caused another line of entrenchments to be constructed about half a mile in rear. By this second line the Federals were suddenly brought up. The confusion was very great, the battalions had intermingled in the excitement of the charge, and the officers could neither make their orders {94} heard nor form their men for another rush. Lee threw in his reserves. He made a tremendous counter-attack. Every single battalion he could collect was ordered to attack, and the vigour of the blow was such that the whole of these 20,000 men were driven back beyond the first line of entrenchments, and the Confederates recaptured their first position" (Henderson).
_He will select positions for the Artillery_, in consultation with the commander of that arm, the objects in view being: to command lines of approach so that the assailant may be shelled and forced to deploy early and so to indicate his plan of attack; to delay the advance; to combine with the infantry in the close defence of the main position; to support local counter-attacks; to destroy hostile batteries by counter-battery work; and to combine eventually in the Decisive Counter-Attack. The increased mobility of guns of the heaviest calibre owing to motor traction, and the increased defensive power of the protective quick-firing small arms, enable guns to be placed close behind the infantry firing line without undue risk of capture.
_He will divide the position into sectors_, each garrisoned by a distinct unit, under a definite commander. The mutually supporting tactical points (farmsteads, villages, woods, ridges, knolls, etc.) will usually be held in groups, under group commanders, with definite subordinate commanders, and the group commander will probably control the local reserves of that group, with which he can assist any of the units in times of need. The units from which such groups are formed will usually be complete sections.
_He will decide the position of the General Reserve_. This will be the locality best suited for the advance to the decisive counter-attack, if it is to be delivered from a distance; or near the point where the enemy's decisive attack is expected, if it is intended to hurl the General Reserve into the flank and rear of the enemy's main {95} attack while it is heavily engaged with the troops holding the position. As surprise is essential to success, the position of the General Reserve should be concealed as long as possible. The position of the General Reserve will depend upon the ascertained intentions of the enemy. At the _Second Battle of the Somme_ (March 21, 1918) the intentions of the German commander were ascertained during the first day's fighting. "As by this time (_i.e._ the evening of March 21) it had become clear that practically the whole of the enemy's striking force had been committed to this one battle, my plans already referred to for collecting reserves from other parts of the British front were put into immediate execution. By drawing away local reserves and thinning out the front not attacked, it was possible to reinforce the battle by eight divisions before the end of the month" (Sir D. Haig's Dispatches).
_He must decide the position_, and to some extent the action, of the Cavalry. Before defensive action in a War of Manoeuvre the cavalry have been out on reconnaissance, and during the early stages they have endeavoured to lure the assailants on to a false position. During the battle they will frustrate the efforts of opposing mounted troops, will protect a vulnerable flank, and will assist generally by dismounted fire action. After the victorious counter-attack they will emerge in pursuit. In case of a reverse they will delay the enemy's victorious advance by fire action and by mounted tactics to protect the withdrawing forces from the depredations of hostile cavalry. A position near a flank will usually be occupied.
There have been many examples of protection by cavalry of a force that has been worsted. After the _Combat of Roliça_ (August 17, 1808) General Delaborde retreated by alternate masses, protecting his movements by short, vigorous charges of cavalry. At _Chancellorsville_ (May 3, 1863), and on the first day of _Gettysburg_ (July 1, 1863), a handful of United States {96} cavalry held up the pursuit and staved off disaster. At _Königgratz_ (_Sadowa_), (July 3, 1866), the charges of the Austrian cavalry drove back the Prussian Horse and enabled Benedek's defeated troops to get back in safety. At _Rezonville_ (August 16, 1870) von Bredow's Cavalry Brigade was ordered to charge the French batteries and their infantry escort, in order to give some breathing time for the hard-pressed Prussian infantry. The charge was successful and the time was gained, but as at _Balaclava_ (October 26, 1854) there were few survivors from "Von Bredow's Todtenritt" (death ride). After the battle of _Le Cateau_ (August 26, 1918) and during the _Retreat from Mons_, the British cavalry, under General Allenby, effectively held off the enemy and enabled the British troops to move unmolested. During the great German offensive in the spring of 1918 the withdrawal of the troops at _Cugny_ (March 24, 1918) was made possible by a brilliant mounted charge by a squadron of the 16th Cavalry Brigade, which broke through the German line, taking over 100 prisoners, and sabring a large number of the enemy. During the retreat in that area units of the 2nd and 3rd Cavalry Divisions proved so effective in delaying the enemy's advance that other units were horsed during the progress of the battle in order to increase the supply of cavalry. "Without the assistance of mounted troops, skilfully handled and gallantly led, the enemy could scarcely have been prevented from breaking through the long and thinly held front of broken and wooded ground before the French reinforcements had had time to arrive. . . . The absence of hostile cavalry at this period was a marked feature of the battle. Had the German command had at their disposal even two or three well-trained cavalry divisions, a wedge might have been driven between the French and British Armies. Their presence could not have failed to have added greatly to the difficulties of our task" (Sir D. Haig's Dispatches).
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_He must select a rallying place_ in rear of the main position from which to recapture the front line, as General Lee recovered the "Salient" in the Wilderness of Virginia.
_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