Part 12
"The first position taken up by a Rear Guard after an unsuccessful fight must be held longer, as a rule, than the subsequent positions, because when once the defeated army has got well away along the roads and has regained some semblance of organisation, the march continues without interruption unless some obstacle has to be crossed" (General Haking, "Staff Rides"). It can also be noted that as it is seldom the intention of the Rear Guard commander to deliver a decisive counter-attack, he can detail a very large proportion of his force to hold the successive positions, with local reserves, for purely local counter-attacks; and for the same reason, an obstacle in front of his position (which would make that position unsuitable for the Active Defence, as it would prevent the advance of the General Reserve to the decisive counter-attack) is most welcome in the Delaying Action of a Rear Guard fighting for time for its Main Body.
When at length a line of resistance is evacuated, the heavy artillery will be withdrawn first to move to a distant fire position, then the slow moving infantry and the light artillery (under the protective fire of the aircraft and mobile troops), and last the cavalry and other mobile troops, who by reason of their superior mobility, can hang on to the last and can protect the flanks of the Rear Guard as they fall back, before {124} resuming their work as a Rear Party, observing and resisting the advanced troops of the pursuing force.
During a close pursuit the Rear Guard commander will be called upon to exercise all his faculties and to exert all his tactical ability in handling his command. One of the most anxious times before him will be when the Main Body is passing through a defile, as such a passage will not only delay its march but will make its columns particularly vulnerable and helpless. In the case of defiles Napoleon's maxim must be borne in mind: "It is contrary to the principles of war to let one's parks and heavy artillery enter a defile if the other end is not held also." At _Sannah's Post_ (March 31, 1900) the train was permitted to enter a defile caused by the banks of the Koorn River without the previous occupation of that defile, and all the wagons were captured. This not only emphasises the necessity for an Advanced Guard in retreat, but points to the need of tactical knowledge on the part of the Rear Guard commander, especially in mountainous country or in terrain cut up by woods and marshes, where the train is liable to cause delays, as the withdrawing force is compelled to march in a long drawn column. Extra time must be gained by the Main Guard to enable the Main Body to emerge from the defile. The Rear Guard commander must therefore adapt his plans to suit the country through which the Main Body has to pass, as well as the country in which he will himself fight Delaying Actions. A good map and ability to use it, and close co-operation with the Main Body, must be determining factors for success or failure.
TRAINING.--When troops are being exercised in Rear Guard work opportunities should be taken to explain the difficulties of choosing suitable positions, of withdrawing from them when involved in battle, of the paramount necessity for mutual support, and of accepting {125} any risk that may be required to safeguard the Main Body. Stress should be laid upon the importance of Fire Tactics (the judicious combination of Fire and Movement), the greatest of all factors in a successful Rear Guard battle, and upon the ability to read and understand a map, an essential qualification in all movements of troops and indispensable in Rear Guard fighting. From the map a platoon commander must be able to predict the probable line of the enemy's advance against the line of resistance as well as the best route to be taken when, at length, he withdraws his platoon to another fire position in rear; while he must be prepared to throw his platoon in local counter-attack on the flank or rear of an assaulting party that has become detached from its supports and therefore affords a fleeting opportunity for a local fighting success, and a rapid advance for this purpose along a route unseen to the foe, a speedy reorganisation after victory, and a rapid withdrawal to the point of issue, or to a line in rear, can best be achieved by use of the map and reconnaissance of the ground of the encounter.
EYE FOR GROUND.--One of the secrets of Napoleon's extraordinary successes was his "eye for ground." "It was not until I went to Jena and Austerlitz that I really grasped what an important part an eye for ground like Napoleon's, or blindness as to ground like his opponent's at both those battles, may play in Grand Tactics, that is, the art of generalship" (Colonel G. F. R. Henderson, "The Science of War"). The same was true of General R. E. Lee, particularly in the Wilderness Campaign, when it was not only the entrenchments but the natural features of the ground on which he relied in his defensive tactics. "His eye for ground must have been extraordinary. The campaign was fought over a very large area, an area of very close country, with few marked natural features; and yet in the midst of woods, jungles, and streams, with very little time at his disposal, he always seems to have selected positions than which none could have been stronger" (Colonel G. F. R. Henderson, "The Science of War").
EXAMPLES OF REAR GUARD WORK.--During the Retreat from Mons the Rear Guard of the II. Corps of the British Expeditionary Force delayed the pursuit by the daring and devotion of its cavalry and artillery, and by subordinating its plans to the interests of the Main Body enabled the Corps Commander (General Sir H. Smith-Dorrien) not only to throw off the pursuit but to effect a junction with the other wing of the British Army. The retreat took place after the First _Battle of Le Cateau_ (August 26, 1914), and during the period of the retreat the insecurity of the British Army through the breakdown of a co-operating force rendered it liable to disaster. But the moral of Marshal French and his commanders, the stubborn fighting instincts of the British race, and the excellence of the musketry training of the Regular Army in times of peace, prevented the retreat from becoming a rout. The care taken in training the troops in Fire Tactics, and particularly in reloading with "eyes on the mark and butts to the shoulder," was most abundantly justified. The accuracy and volume of the rifle fire deceived the enemy as to the nature of the troops employed against them, and the dismounted troops and infantry with their rifles were reported as "battalions of machine gunners."
During the _Second Battle of the Somme_ (March, 1918), the British III, and V. Armies fought a series of Rear Guard battles, and the enemy's advance was made at a very heavy cost. "Units retreated stubbornly from one position to another as they found them turned and threatened with isolation; but at many points fierce engagements were fought, and whenever the enemy attempted a frontal attack he was beaten off with loss" (Sir D. Haig's Dispatches). The machine gun proved its effectiveness again and again during the British {127} withdrawal, and twelve machine guns of the 63rd Division, posted in _Les Boeufs_ (March 24, 1918), held up the enemy's advance from Morval at a critical period, and enabled the division to reach the position assigned to it. The losses inflicted on the enemy by machine-gun and rifle and Lewis-gun bullets were so heavy that by March 25 Von Below's XVII. Army was described in German dispatches as "quite exhausted." During the same battle a detachment of about 100 officers and other ranks, under the command of the Brigade-Major of the 61st Brigade, held the enemy at bay from early morning until 6 p.m. at _Le Quesnoy_ (March 27, 1918) and enabled the 20th Division to retire to its destined position.
At the _Combat of Roliça_ (August 17, 1808) the French General Delaborde was outnumbered by the Anglo-Portuguese forces under Sir A. Wellesley, and being driven from his first and second positions he withdrew to the mountains. During his retreat "he brought every arm into action at the proper time . . . and retreated by alternative masses, protecting his movements by short, vigorous charges of cavalry . . . and he fell back, disputing the ground, to Quinta de Bugagliera" (Napier).
In December, 1808, and January, 1809, General Sir John Moore withdrew to Coruña before the armies of Napoleon (and when the Emperor returned to Madrid, before those of Marshal Soult). "He conducted his long and arduous retreat with sagacity, intelligence, and fortitude" (Napier), and it is interesting to note that as in the Retreat from Mons in 1914 and at the Second Battle of the Somme in 1918, so in the rear-guard actions which preceded the embarkation of Sir John Moore's Army, the musketry of the British troops was the deciding factor: "the English muskets were all new, the ammunition fresh; and whether from the peculiar construction of the muskets, the physical strength and coolness of the men, or all combined, {128} the English fire is the most destructive known" (Napier).
At _Bristow Station_ (October 14, 1863) during General Meade's campaign in Northern Virginia (after his defeat of General Lee at Gettysburg, July 1-3, 1863), a surprise attack by Stuart's cavalry and infantry from General Rode's Division caused the withdrawal of the Federal troops. General Warren covered the retirement and eventually withdrew his own forces unmolested after beating off several attacks with close-range musket fire.
Jean Victor Moreau, one of the greatest generals of the French Republic, became a general of division at the age of 33, and by his skill in extricating his forces from apparently certain disaster established in retreat a far greater reputation for generalship than his brilliant victories secured for him. In the spring of 1796 he defeated Latour at _Rastatt_ and the Archduke Charles at _Ettlingen_, and drove the Austrians back to the Danube, but owing to the defeat and retreat of Jourdan he was compelled to regain the Rhine in a desperate and apparently hopeless effort. Yet he not only preserved his army intact but brought with him over 5,000 prisoners. In 1798 he again saved his army from destruction when hard pressed by the Russians and Austrians in Italy. Retreat was by no means his only or favourite manoeuvre, as he subsequently gained victory after victory over the Austrians in the campaign of 1800, drove them back behind the River Inn, and won the decisive victory of _Hohenlinden_ (December 3, 1800), where the Austrians and their Bavarian allies lost 17,000 men and 74 guns against a total loss of 5,000 on the side of the French.
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OUTPOSTS
Opposing forces come into conflict through the encounter of the Advanced Guards of moving columns; through the approach of a pursuing force to the Rear Guard of a retreating enemy; through the attack of a moving force on an enemy in position; and through the renewal of an engagement which has died down between opposing forces.
Every commander will endeavour to prevent interference with his plans and future movements, and while striving to surprise and outwit the enemy he will exert every endeavour to prevent the application of this vital principle by the enemy. The commander of a force that is at rest will require security for that force in order that its rest may be undisturbed, and he will require the security to be assured in order that his plans for the overthrow of the enemy may be developed. He will, therefore, detach a portion of his force to ensure this security by observation, to prevent the secret occupation of localities the hostile possession of which will interfere with his plans; and by resistance to hostile movements he will secure the rest of the Main Body.
The force detailed to protect troops at rest is known as Outposts, and their duty is to preserve the security of the Main Body. Outposts protect the Main Body from surprise by Observation, and if attacked they gain time by Resistance until the commander of the Main Body can put his plans into execution by the occupation of the position in which he intends to receive attack. Observation is carried out by Aircraft, by Patrols (mobile troops by day and infantry by night), and by Sentries; Resistance is provided by Sentry Groups and by troops {130} in defensive positions, called the Piquets, which have other troops as Supports. In certain cases a Local Reserve and a General Reserve are also provided.
STRENGTH.--Work in the Outpost Line is most exhausting. Not a man or a horse should be employed there if their services can be dispensed with, and although the number of troops allotted for the work depends almost entirely upon the nature of the country and the tactical situation, it is laid down in the text-books that if an unnecessarily large proportion of the whole force is so employed the force will suffer in efficiency. It can also be seen that although the work is of the first importance and fraught with the greatest difficulties, it is clearly possible for a comparatively small body of troops to carry it out. Observation requires intelligence and vigilance rather than numbers; Resistance can be provided by the Delaying Action on a wide front of small numbers of skilled troops with the relative advantage conferred upon them in defence by machine guns and small arms, and with the assurance of support from their Main Body close at hand.
OBSERVATION.--A force can only be regarded as secure from surprise when every body of the enemy within striking distance is so closely watched that it can make no movement by night or day without its becoming known immediately to the observers of the Outposts. By day the Outpost commander will carry out Reconnaissance some distance ahead of his position by means of Aircraft and Patrols of mounted troops and cyclists, while the commander of each Outpost company keeps the approaches to the position under observation by sentries, so posted as to see and hear unobserved by a hostile force. By night, the Aircraft and mounted troops are unable to render much assistance as moving patrols, and the work of Reconnaissance and Observation falls upon the platoons of the Outpost companies.
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RESISTANCE.--For the purposes of Resistance the Outpost commander will rely upon his infantry and upon such artillery and machine guns as may be allotted to him, and if the area he is occupying is that in which the commander of the Main Body will meet attack the Outposts will be provided with a greater proportion of artillery and machine guns. Resistance is offered by the entrenchment of each Sentry Group in an all-round post, and depth and elasticity are given to the defence by the establishment of entrenched Piquets in selected, mutually supporting positions commanding with their fire every avenue of approach, covering the flanks of neighbouring Piquets, and so arranged in plan as to bring converging fire upon the enemy as he advances to the attack. These Piquet positions will be strengthened, when required, by the Supports, who will either assist in manning the defences of the Piquets or will occupy similarly prepared defensive posts on the flank. Local Reserves may sometimes be required for local counter-attacks, and in certain cases a General Reserve is provided. The degree of Resistance to be offered by the Sentry Groups depends on the tactical situation and will be specified by the Outpost commander. In certain cases the Sentry Groups are permitted in face of a heavy attack to fall back to the Piquets, but if they do so they must be warned of the danger of arriving headlong on the Piquet only just ahead of the enemy. In consequence of this danger such retirements are rarely permissible at night. The Piquets are generally posted on the Outpost Line of Resistance, in which case they hold their positions to the last man and the last round, until further orders are received from the commander of the force protected.
DISTANCE.--The distance of the Outpost position from the troops protected is regulated by the time the latter will require to prepare for action and by the importance of preventing the enemy's field artillery from {132} approaching within effective range of the ground on which these troops will deploy if attacked. Heavy guns and mortars, although motor traction gives them great mobility, are unlikely to accompany the enemy's Advanced Guard, and preparation to withstand or prevent their fire will not usually be required from Outpost troops. The effective range of shrapnel is 5,500 yards, the limit of the effective range of machine guns is 2,000 yards, and of Lewis guns and rifles the effective limit is 1,400 yards. The position on which the Main Body will deploy will thus be protected from the shrapnel of field artillery, if the possible fire-positions of that arm are brought under effective fire from machine guns 3,500 yards from the Position of Deployment, with Lewis guns and rifles about 500 yards further forward. On the other hand, especially in the case of small forces (against which artillery will not be likely to be sent), the distance must not be such as would permit of the Outposts being cut off, or as would necessitate the employment of an undue proportion of men on Outpost duty.
THE OUTPOST COMMANDER.--Before halting, a commander should first decide on his dispositions in case of attack, and then arrange the quartering of his command and the general position of the Outposts. In the case of a small independent force the commander of the force will usually himself detail the whole of the Outpost troops, and will either retain the command in his own hand or appoint an officer to command them, In such a case the disposition of the troops will probably be that of a perimeter camp, preparation being made against attack from all directions. In the case of large bodies Outpost troops will usually consist of all arms, and a definite commander will always be appointed. This commander will, when necessary, divide the Outpost line into sectors, delegating responsibility for the holding of each sector to the commander of a subordinate unit or formation, and defining the limits {133} of sectors by distinctive features such as trees, cottages, or streams. The tops of hills or the bottoms of valleys are not suitable as tactical boundaries, and roads should be inclusive to one or other sector, for a road used as a boundary may be neglected by one of the commands it divides under the impression that it is the duty of the other command to patrol it.
INFORMATION AND ORDERS.--The Outpost commander must have definite information on the following points:--
I. What is known of the enemy and information concerning friendly bodies of troops working against the enemy.
II. The intentions of the commander of the force he is protecting, where the Main Body will rest and the period it will stay there, and whether it is intended to engage the enemy if he advances, and if so on what position.
III. The general line of the Outposts, the troops at disposal for the work, and whether there are other troops on the left and right.
IV. The hour at which the Outposts are to be relieved and the place to which reports are to be sent.
After receiving the above information he will give such orders as are immediately necessary for protection against surprise. He will then allot the task of Observation to his mobile troops and will decide on a Line of Resistance for the Outpost troops. He will co-ordinate his arrangements with those of neighbouring Outpost commanders and will ensure that no ground on his flanks remains unwatched.
The Outpost commander will then issue orders to his subordinate commanders on the following points:--
(1) Information concerning the enemy and his own troops so far as they affect the Outposts.
(2) The general line to be occupied and his frontage and limits of each subordinate commander.
(3) The distribution of the mobile troops, artillery, and machine guns.
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(4) Instructions as to the degree of resistance to be offered and the general line of the Outpost Line of Resistance.
(5) Special arrangements by night.
(6) Regulations as to smoking, fires, and cooking.
(7) The hour at which the Outposts will be relieved.
(8) The place to which reports are to be sent.
(9) Instructions as to the accommodation of the Reserves (if any are provided) and whether the Supports (and Reserves, if any) may take off accoutrements, etc.
When he receives information that the Outposts are in position, he will transmit the information to the commander who appointed him.
THE OUTPOST LINE OF RESISTANCE.--Retirements under fire to a supporting line are dangerous, especially at night. As a general rule, therefore, the Piquets should be posted on the Outpost Line of Resistance. Co-operation, intercommunication, and the exercise of command will be facilitated by placing the Piquets along well-defined natural features, or in the vicinity of roads. But the tactical situation may demand that the line adopted should afford facilities for a most stubborn resistance as well as facilities for observation, and the former necessity will far outweigh the latter.
If the force is likely to remain halted for several days, especially if the operations are likely to lapse into Position Warfare, commanding ground is of great value to the artillery, and the Outpost Line of Resistance will probably develop into the Outpost zone of a defensive position. On the other hand, if halted for only one night, artillery will not be largely employed, and commanding ground is not essential.