CHAPTER I
THE THEORY OF SECURITY
(Copied from the Field Service Regulations)
GENERAL PRINCIPLES
Security embraces all those measures taken by a command to protect itself from observation, annoyance, or surprise by the enemy.
Ordinarily this security is provided in part by cavalry. But as a command is not always preceded by cavalry, and as this cavalry can not always prevent sudden incursions of the enemy or discover his patrols, additional security becomes necessary. This is obtained by covering the immediate front of the command with detachments.
On the march these detachments are called advance, flank, or rear guards; in camp or bivouac they are called outposts.
The object of the former is to facilitate the movement of the main body and to protect it from surprise and observation; the object of the latter is to secure the camp or bivouac against surprise and to prevent an attack upon it before the troops can prepare to resist.
On the march these detachments facilitate the advance of the main body by promptly driving off small bodies of the enemy who seek to harass or delay it; by removing obstacles from the line of advance; by repairing roads, bridges, etc., thus enabling the main body to advance uninterruptedly in convenient marching formations.
They protect the main body by preventing the enemy from firing into it when in close formation; by holding the enemy and enabling the main body to deploy before coming under effective fire; by preventing its size and condition being observed by the enemy; and, in retreat, by gaining time for it to make its escape or to reorganize its forces.
As the principal duty of these bodies is the same, viz., that of protecting the main body, there is a general similarity in the formations assumed by them. There is (1) the cavalry covering the front; next, (2) a group, or line of groups, in observation; then (3) the support, or line of supports, whose duty is to furnish the observation groups, and check the enemy pending the arrival of reinforcements; still farther in rear is (4) the reserve.
An advance or flank guard commander marches well to the front, and, from time to time, orders such additional reconnaissance or makes such changes in his dispositions as the circumstances of the case demand.
In large commands troops from all arms are generally detailed, the proportion from each being determined by the tactical situation; but commanders detail no more troops than the situation actually requires, as an excessive amount of such duty rapidly impairs the efficiency of a command. As a general rule troops detailed on the service of security vary in strength from one twentieth to one third of the entire command, but seldom exceed the latter. When practicable, the integrity of tactical units is preserved.
In mixed commands infantry usually forms the greater part of the troops detailed to the service of security. Cavalry is assigned to that duty whenever advantage can be taken of its superior mobility. The kind and amount of artillery are determined by circumstances.
The field trains of troops on this duty generally remain with the field train of the command, but if conditions permit they may join their organizations.
Troops on the service of security pay no compliments; individuals salute when they address, or are addressed by, a superior officer.
ADVANCE GUARDS
An advance guard is a detachment of the main body which precedes and covers it on the march.
Its duties are:
(1) To guard against surprise and furnish information by reconnoitering to the front and flanks.
(2) To push back small parties of the enemy and prevent their observing, firing upon, or delaying the main body.
(3) To check the enemy's advance in force long enough to permit the main body to prepare for action.
(4) When the enemy is encountered on the defensive, to seize a good position and locate his lines, care being taken not to bring on a general engagement unless the advance-guard commander is empowered to do so.
(5) To remove obstacles, repair the road, and favor in every way possible the steady march of the column.
STRENGTH AND COMPOSITION
Subject to variation according to the situation, one twentieth to one third of a command may be assumed as a suitable strength for the advance guard. The larger the force, the larger in proportion is the advance guard, for a large command takes relatively longer to prepare for action than a small one. In large commands it is usually composed of all arms, the proportions depending on the nature of the work, character of the country, etc.
DISTANCE FROM THE MAIN BODY
While the distance between these two bodies should be great enough to prevent needless interruptions in the march of the main body, and to give the latter time to deploy should the enemy be encountered, it should never be so great that timely support of the advance guard becomes impracticable.
PLATE SHOWING the IDEAS INVOLVED IN an ADVANCE GUARD
As you go from the point to the main body note that the distances are greater as the groups become larger. Larger groups require more time and space, when getting ready for action, than small groups. A very important thing to remember in connection with this plate is that you have only such groups in an advance guard as are necessary to insure protection for the main body." />
PLATE SHOWING the IDEAS INVOLVED IN an ADVANCE GUARD
As you go from the point to the main body note that the distances are greater as the groups become larger. Larger groups require more time and space, when getting ready for action, than small groups. A very important thing to remember in connection with this plate is that you have only such groups in an advance guard as are necessary to insure protection for the main body.
DISTRIBUTION OF TROOPS
An advance-guard order generally describes the following distribution of troops:
/P Advance cavalry. Support. Reserve. P/
The manner in which the advance-guard cavalry is employed depends upon the situation. Its proper place is in the direction of the enemy, and generally all or the greater part is used as advance cavalry. If weak in numbers, it may be assigned to the support.
ADVANCE CAVALRY
The advance cavalry is that part of the advance-guard cavalry preceding the support. It reconnoiters far enough to the front and flanks to guard the column against surprise by artillery fire, and to enable timely information to be sent to the advance-guard commander.
SUPPORT
Following the advance cavalry is the support, varying in strength from one fourth to one half of the advance guard. In mixed commands it consists of infantry, to which engineers may be attached. If there is no advance cavalry, some cavalry should be attached to the support for reconnoitering duty.
As the support moves out it sends forward an advance party several hundred yards, the distance varying with the terrain and the size of the command.
The advance party supplements the work of the advance cavalry, reconnoitering to the front and flanks to guard the support against surprise by effective rifle fire. The patrol preceding the advance party on the line of march is called the point, and is commanded by an officer or an experienced noncommissioned officer.
With the advance cavalry in front but little reconnoitering by infantry is necessary, and the advance party is relatively small--one eighth to one third of the support. If there is no advance cavalry, the advance party is made stronger (about one half of the support) and the flanks are guarded, if necessary, by additional patrols sent out from the support and even from the reserve.
The support commander ordinarily marches with the advance party, but goes wherever needed. He sees that the proper road is followed; that guides are left in towns and at crossroads; that necessary repairs are made to roads, bridges, etc., and that information of the enemy or affecting the march is promptly transmitted to the advance-guard commander. He endeavors promptly to verify information of the enemy.
RESERVE
The reserve follows the support at several hundred yards' distance. It consists of the remainder of the infantry and engineers, the artillery, and the ambulance company. The artillery usually marches near the head of the reserve, the engineers (with bridge train, if any) and special troops at the rear.
RECONNAISSANCE
In conducting the reconnaissance the patrols are, as a rule, small--from two to six men. If additional protection is necessary, a flank guard covers the threatened flank. The flanking patrols, whether of the advance cavalry or advance party, are sent out to examine the country wherever the enemy might be concealed. If the nature of the terrain permits, these patrols march across country or along roads and trails paralleling the march of the column. For cavalry patrols this is often possible; but with infantry patrols and even with those that are mounted, reconnaissance is generally best done by sending the patrols to high places along the line of march to overlook the country and examine the danger points. These patrols report or signal the results of their observations and, unless they have other instructions, join their units by the most practicable routes, other patrols being sent out as the march proceeds and as the nature of the country required.
Deserters, suspicious characters, and bearers of flags of truce, the latter blindfolded, are taken to the advance-guard commander.
Civilians are not permitted to precede the advance guard.
Communication between the fractions of an advance guard and between the advance guard and main body is maintained by wire, messenger service, or signals.
ADVANCE GUARD OF A SMALL COMMAND
In forming the advance guard of a command smaller than a brigade, the foregoing distribution is modified, depending upon the situation. A company or troop usually sends forward only a point, a battalion or squadron, an advance party; but a battalion or squadron at war strength should put a company or troop in the advance guard and a regiment should put a battalion or squadron, if an enemy is liable to be met. Whenever the advance guard is less than a battalion, there is no reserve.
REAR GUARDS
The rear guard is charged with the important duty of covering the retreat.
When a commander decides to retreat, he issues the necessary order. During a retreat the outpost for the night usually forms the rear guard of the following day.
STRENGTH AND COMPOSITION
The strength of a rear guard depends upon the nature of the country and the strength and character of the pursuing force. It can not, like the advance guard, count on the support of the main body.
Machine guns are especially useful in the passage of defiles and in covering the crossings of rivers.
Engineers and ambulance companies are usually assigned to rear guards.
The troops of a rear guard are selected from those that have had previous local successes, or have suffered little loss and are comparatively fresh.
DISTRIBUTION OF TROOPS
The proximity and conduct of the enemy control, to a large extent, the formation of a rear guard. When it is not necessary to withdraw in deployed lines, the greater part of the rear guard marches on the road in column of route, taking up a formation resembling that of an advanced guard faced to the rear. The distribution of troops is therefore similar to that of an advance guard, namely:
/P Reserve. Support. Rear cavalry. P/
The rear cavalry is that portion of the rear-guard cavalry following the support. The support, as in an advance guard, is divided into two parts; that part nearest the enemy is called the rear party and marches with a rear point.
DISTANCES
The distance of the rear guard from the main body and between the fractions of the rear guard are about the same as in the case of an advance guard. If marching at night, the rear guard draws nearer the main body.
REAR GUARD OF AN ADVANCING FORCE
If there is a possibility that the rear of the column may be attacked, a rear guard of suitable strength and composition is provided, its conduct is practically the same as that of the rear guard of a retreating force. It generally marches in rear of the trains, those organizations following the combatant troops without distance.
OUTPOSTS
The size and disposition of the outpost will depend upon many circumstances, such as the size of the whole command, the proximity of the enemy and the situation with respect to him, the nature of the terrain, etc.
A suitable strength may vary from a very small fraction to one third of the whole force. For a single company in bivouac a few sentinels and patrols will suffice; for a large command a more elaborate outpost system must be provided. It should be no stronger than is consistent with reasonable security.
The most economical protection is furnished by keeping close contact with the enemy by means of outpost patrols, in conjunction with resisting detachments on the avenues of approach.
The outpost should be composed of complete organizations.
The positions held by the subdivisions of the outpost should generally be prepared for defense, but conditions may render this unnecessary.
Troops on outpost keep concealed as much as is consistent with the proper performance of their duties; especially do they avoid appearing on the sky line.
COMPOSITION
A mixed outpost is composed principally of infantry. The infantry is charged with the duty of local observation, especially at night and with resisting the enemy long enough for the main body to prepare for action. The cavalry is charged with the duty of reconnaissance, and is very useful in open country during the day. If the infantry has been severely taxed by marching or fighting, a large part of the outpost may be temporarily formed of cavalry.
Artillery is useful to outposts when its fire can sweep defiles or large open spaces and when it commands positions that might be occupied by hostile artillery. The guns are carefully concealed or protected and are usually withdrawn at night.
Machine guns are useful to command approaches and check sudden advances of the enemy.
The field trains of troops on outpost duty generally join their organizations; if an engagement is probable, they may be held in rear.
DISTRIBUTION OF OUTPOST TROOPS
The outpost will generally be divided into four parts. These, in order from the main body, are the reserve, the line of supports, the line of outguards, and the advance cavalry.
The distance separating these parts, and their distance from the main body, will depend upon the object sought, the nature of the terrain, and the size of the command. There can be no uniformity in the distance between supports and reserve, nor between outguards and supports, even in the same outpost. The avenues of approach and the important features of the terrain will largely control their exact positions.
The outpost of a small force should ordinarily hold the enemy beyond effective rifle range of the main body until the latter can deploy. For the same purpose the outpost of a large force should hold the enemy beyond the artillery range.
The reserve constitutes the main body of the outpost and is held at some central point from which it can readily support the troops in front or hold a rallying position on which they may retire. The reserve may be omitted when the outpost consists of less than two companies.
The reserve may comprise one-fourth to two-thirds of the strength of the outpost.
The supports constitute a line of resisting and supporting detachments, varying in size from a half company to a battalion. They furnish the line of outguards.
The supports are numbered consecutively from right to left. They are placed at the more important points on the outpost line, usually in the line on which resistance is to be made in case of attack.
As a general rule, roads exercise the greatest influence on the location of supports, and a support will generally be placed on or near a road. The section which it is to cover should be clearly defined by means of tangible lines on the ground and should be such that the support is centrally located therein.
The outguards constitute the line of small detachments farthest to the front and nearest to the enemy. For convenience they are classified as pickets, sentry squads, and cossack posts. They are numbered consecutively from right to left in each support.
A picket is a group consisting of two or more squads, ordinarily not exceeding half a company, posted in the line of outguards to cover a given sector. It furnishes patrols and one or more sentinels, double sentinels, sentry squads, or cossack posts for observation.
Pickets are placed at the more important points in the line of outguards, such as road forks. The strength of each depends upon the number of small groups required to observe properly its sector.
A sentry squad is a squad posted in observation at an indicated point. It posts a double sentinel in observation, the remaining men resting near by and furnishing the reliefs of sentinels. In some cases it may be required to furnish a patrol.
A cossack post consists of four men. It is an observation group similar to a sentry squad, but employs a single sentinel.
At night it will sometimes be advisable to place some of the outguards or their sentinels in a position different from that which they occupy in the day time. In such case the ground should be carefully studied before dark and the change made at dusk. However, a change in the position of the outguard will be exceptional.
Sentinels are generally used singly in daytime, but at night double sentinels will be required in most cases. Sentinels furnished by cossack posts or sentry squads are kept near their group. Those furnished by pickets may be as far as 100 yards away.
Every sentinel should be able to communicate readily with the body to which he belongs.
Sentinel posts are numbered consecutively from right to left in each outguard. Sentry squads and cossack posts furnished by pickets are counted as sentinel posts.
By day, cavalry reconnoiters in advance of the line of observation. At night, however, that the horses may have needed rest and because the work can be done better by infantry, the greater part of the cavalry is usually withdrawn in rear of the supports, generally joining the reserve, small detachments being assigned to the supports for patrolling at a distance.
With efficient cavalry in front, the work of the infantry on the line of observation is reduced to a minimum.
General instructions for the advance cavalry are given by the outpost commander, but details are left to the subordinate.
Instead of using outguards along the entire front of observation, part of this front may be covered by patrols only. These should be used to cover such sections of the front as can be crossed by the enemy only with difficulty and over which he is not likely to attempt a crossing after dark.
In daylight much of the local patrolling may be dispensed with if the country can be seen from the posts of the sentinels. However, patrols should frequently be pushed well to the front unless the ground in that direction is exceptionally open.
Patrols or sentinels must be the first troops which the enemy meets, and each body in rear must have time to prepare for the blow. These bodies cause as much delay as possible without sacrificing themselves, and gradually retire to the line where the outpost is to make its resistance.
Patrols must be used to keep up connection between the parts of the outpost except when, during daylight, certain fractions or groups are mutually visible. After dark this connection must be maintained throughout the outpost except where the larger subdivisions are provided with wire communication.
In addition to ordinary outguards, the outpost commander may detail from the reserve one or more detached posts to cover roads or areas not in the general line assigned to the supports.
In like manner the commander of the whole force may order detached posts to be sent from the main body to cover important roads or localities not included in the outpost line.
The number and strength of detached posts are reduced to the absolute needs of the situation.
ESTABLISHING THE OUTPOST
The outpost is posted as quickly as possible, so that the troops can the sooner obtain rest. Until the leading outpost troops are able to assume their duties, temporary protection, known as the march outpost, is furnished by the nearest available troops.
The halt order of the commander, besides giving the necessary information and assigning camp sites to the parts of the command, details the troops to constitute the outpost, assigns a commander therefor, designates the general line to be occupied, and, when practicable, points out the position to be held in case of attack.
The outpost commander, upon receipt of this order, should issue the outpost order with the least practicable delay. In large commands it may often be necessary to give the order from the map, but usually the outpost commander will have to make some preliminary reconnaissance, unless he has an accurate and detailed map.
The order gives such available information of the situation as is necessary to the complete and proper guidance of subordinates; designates the troops to constitute the supports; assigns their location and the sector each is to cover; provides for the necessary detached posts; indicates any special reconnaissance that is to be made; orders the location and disposition of the reserve; disposes of the train if same is ordered to join the outpost; and informs subordinates where information will be sent.
After issuing the initial orders, the outpost commander inspects the outpost, orders the necessary changes or additions, and sends his superior a report of his dispositions.
The reserve is marched to its post by its commander, who then sends out such detachments as have been ordered and places the rest in camp or bivouac, over which at least one sentinel should be posted. Connection must be maintained with the main body, the supports, and nearby detached posts.
The supports march to their posts, using the necessary covering detachments when in advance of the march outpost. A support commander's order should fully explain the situation to subordinates, or to the entire command, if it be small. It should detail the troops for the different outguards and, when necessary, define the sector each is to cover. It should provide the necessary sentinels at the post of support, the patrols to be sent therefrom, and should arrange for the necessary intrenching. Connection should be maintained with the adjoining supports and with the outguards furnished by the supports.
In posting his command the support commander must seek to cover his sector in such manner that the enemy cannot reach, in dangerous numbers and unobserved, the position of the support or pass by it within the sector intrusted to the support. On the other hand, he must economize men on observation and patrol duty, for these duties are unusually fatiguing. He must practise the greatest economy of men consistent with the requirements of practical security.
As soon as the posting of the support is completed, its commander carefully inspects the dispositions and corrects defects, if any, and reports the disposition of his support, including the patrolling ordered, to the outpost commander. This report is preferably made by means of a sketch.
Each outguard is marched by its commander to its assigned station, and especially in the case of a picket, is covered by the necessary patrolling to prevent surprise.
Having reached the position, the commander explains the situation to his men and establishes reliefs for each sentinel, and, if possible, for each patrol to be furnished. Besides these sentinels and patrols, a picket must have a sentinel at its post.
The commander then posts the sentinels and points out to them the principal features, such as towns, roads, and streams and gives their names. He gives the direction and location of the enemy, if known, and of adjoining parts of the outpost.
He gives to patrols the same information and the necessary orders as to their routes and the frequency with which the same shall be covered. Each patrol should go over its route once before dark.
Every picket should maintain connection by patrols with outguard on its right and left. Each commander will take precaution to conceal his outguard and will generally strengthen his position by intrenching.
RELIEVING THE OUTPOST
Evening and shortly before dawn are hours of special danger. The enemy may attack late in the day in order to establish himself on captured ground by intrenching during the night; or he may send forward troops under cover of darkness in order to make a strong attack at early dawn. Special precaution is therefore taken at those hours by holding the outpost in readiness, and by sending patrols in advance of the line of observation. If a new outpost is to be established in the morning, it should arrive at the outpost position at daybreak, thus doubling the outpost strength at that hour.