guards. They may protect their outward flanks by smaller flanking detachments. They must keep in touch with the main body by means of messengers or patrols. The guiding principles in the conduct of flank guards are rapid warning of the presence of an enemy and stubborn resistance to gain time.

Exploration and rapid communication require assignment of cavalry to flanking detachments. They will usually be composed exclusively of that arm, but when strong positions are to be held, or prolonged resistance to the enemy is expected, troops of all arms will be necessary.

112. When the main body executes a flank march near the enemy the flank guard becomes a body of great importance. On account of the hazardous nature of the operations the trains usually conform to the movement at a safe distance from the enemy. When the flank march results from a considerable change of direction effected by the column, it will generally be advisable to convert the advance guard into a flank guard and detail a new and smaller advance guard to precede the column.

REAR GUARDS.

113. In a defeated force the rear guard has the important duty of covering the retreat. It can not, like the advance guard, count upon the support of the main body. On the other hand, it will more often have an opportunity to fight on ground of its own selection. In good defensive positions, with natural or artificial obstacles, it can force the enemy to deploy his troops and to make detours, all of which takes up time. It will be a decided advantage if this result can be accomplished without involving the infantry of the rear guard in a serious engagement. The rear guard must be prepared, however, to render stubborn resistance and to submit to such sacrifices as the circumstances may demand.

114. Strength and composition.—A rear guard will usually be a fighting force composed of the three arms. Its strength will vary with the nature of the country and the character of the pursuit. In some cases it should be somewhat stronger than an advance guard, especially in field artillery, the advantage of the latter being due to its mobility and the fact that it can force the enemy's troops to deploy at long range. A detachment of about one-sixth of the whole force would in ordinary cases furnish a suitable rear guard.

A relatively large force of cavalry will be required to maintain contact with the enemy and to look out for the flanks. Some

mounted engineers should be at hand to prepare obstructions and to execute demolitions at the last moment. Ambulances with necessary personnel of the hospital corps should always be attached to a rear guard.

The troops for a rear guard should be selected from those which have had previous local successes, or have suffered but slight loss and are comparatively fresh.

115. Distance.-The distance of the rear guard from the main body will vary according to circumstances. As a rule it should be about the same as the distance of an advance guard. If marching at night the rear guard draws nearer to the main body.

116. Formation.-The proximity and conduct of the enemy will 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 will march on the road in column of route, taking up a formation which resembles that of an advance guard faced to the The division of the rear guard into parts is similar to that of an advance guard, namely, reserve, support, and rear party with rear point.

rear.

117. The reserve will usually be composed of infantry and artillery, with some cavalry for purposes of communication. Engineers will be at the rear of the reserve, except the mounted detachment, which may be with the support, or temporarily with the rear party. The remainder of the rear guard would generally be composed of cavalry, but it may be necessary on account of weakness of the rear guard cavalry to form the support of infantry. The rear party and its point should be cavalry.

118. The rear guard cavalry gives way before the enemy's pursuit when absolutely necessary, maintains communication with and sends information to the rear guard, and pays special attention to the weak points in a retreat, namely, the flanks. It must make use of all the various kinds of action of which it is capable, according to circumstances, and unless greatly outnumbered by hostile cavalry should of itself cause considerable delay to the enemy.

119. Cavalry not needed in the rear guard may be formed into independent bodies with horse artillery and may remain under direct control of the commander of the entire force. By taking up successive positions on the flanks of the line of march it may greatly facilitate the retreat.

120. Action of a rear guard.-When the enemy is conducting an energetic pursuit the rear guard effects its withdrawal by taking up a succession of defensive positions and compelling the enemy to

attack or turn them. When the enemy's dispositions are nearly completed the rear guard begins to fall back, the cavalry on the flanks being usually the last to leave. The troops already in the next position cover the withdrawal with their fire, and the rearmost troops march past them to another good position. The repetition of this process results in the desired gain of time, especially when it is difficult for the enemy to march across country in deployed formation. 121. In occupying rear guard positions it is desirable (1) to make as strong a display of force as possible and (2) to make sure of good lines of retreat. The latter, and the successive positions, should be reconnoitered by staff officers, and it may be of advantage to cut wire fences and make other hasty preparations to facilitate the march of the troops.

122. The first consideration in a position for artillery of the rear guard is that it shall be able to open fire on the enemy at long range and thus compel his deployment. Field artillery in flank positions is very effective when able to open oblique or enfilading fire on the enemy's lines; it must be accompanied by a strong mounted escort. 123. The pursuit may be delayed by obstacles placed in the enemy's path. Bridges may be burnt or blown up, boats removed or destroyed, fords and roads obstructed, tracks torn up, telegraph lines cut, and houses, villages, woods, or fields fired. Demolitions and obstructions should be prepared by troops detailed from the main body or the reserve and completed by the mounted engineer troops of the rear guard at the last moment.

The instructions of the commander in chief will govern in the demolition of important constructions.

Rear guard of an advancing force.

124. When there is no danger of attack on the rear of the column the rear guard will be small. It is composed of infantry, with some mounted men, and serves mainly for police purposes, as stated in paragraph 239. It marches about 100 yards in rear of the column, or in rear of the regimental trains when they are present with the command.

When trouble is apprehended from guerrillas, marauders, etc., it will have to be stronger, especially in mounted troops.

If there is a possibility that the rear of the column may be attacked by the enemy, the rear guard should be composed of all arms and sufficiently strong to meet all emergencies. In such cases the same principles will apply in its conduct as in the rear guard of a retreating force.

OUTPOSTS.

General principles.

125. The duties of outposts may be summed up in the words reconnaissance, observation, and resistance.

The reconnaissance which finds the enemy and watches his every movement renders surprise impossible. Efficient exploration is therefore the first step toward security; its importance increases with the degree of proximity of the enemy. This duty is generally assigned to the cavalry, whereas local observation, especially at night, and determined resistance which gains time for the main body to develop its course of action, fall principally to the infantry.

126. The formation of the outpost must be such that all lines of approach from the direction of the enemy will be covered. This necessitates a radiating arrangement of the outpost troops, the result being that the ground occupied will, in its general outlines, resemble an open fan. Extensive positions will, when necessary, be divided into sections.

As movement of troops across country, especially at night, is more or less difficult, the first consideration in establishing outposts is to command the roads.

When troops have been facing each other for some time, vigilance should be increased. If at the end of a march the halt is for the night only, simple measures, such as detached posts and pickets on important roads and a few patrols will generally suffice.

When deployed troops suspend hostilities for the night, they will often be obliged to bivouac in line of battle. In such cases surprise is prevented by posting sentinels and sending out patrols, covering detachments would only serve to interfere with effective fire of the line in case of attack.

Fresh troops should be designated to form the outposts which are established after an engagement.

127. At the end of a march the advance guard takes up outpost duty; in small commands it may be necessary to devote the entire advance guard to this purpose. When the duties of the advance guard have been particularly arduous, it should be relieved by fresh troops as soon as practicable after the end of the day's march. Cavairy out in front should remain there until dusk, unless sooner relieved.

In the case of a force marching to the rear, the outpost would be established by the rear guard; however, when the enemy has been

conducting an active pursuit the outpost should, if practicable, be established from the main body so as to relieve the rear guard as it marches through the outpost position. If the retreat is continued next day, the outpost would, as a rule, form the rear guard.

128. At sieges, continuity in the line of observation and uniformity in the distribution of the fractions of outposts may be desirable; but in the usual field operations the conditions are so various that normal formations in almost all cases require much modification. The arrangements and instructions should be regulated by the special circumstances of each case.

129. Officers on outpost duty should be allowed great latitude so long as their dispositions are calculated to insure sufficient warning of attack, adequate resistance, and close cooperation between the parts of the outposts.

All troops on outpost duty should be carefully concealed, and all movements should be made so as to escape observation by the enemy. 130. Outposts should not endeavor to bring on combats. Unnecessary firing disturbs the rest of the main body without compensating results, and when frequently indulged in ceases to be a warning; moreover it may bring on an engagement of a magnitude beyond the control of the outposts. In special cases activity at the outposts may be ordered with a view to wearing out or deceiving the

enemy.

131. Shortly before dawn and at dusk are the hours of special danger. The enemy may attack late in the day in order to establish himself in captured ground by intrenching during the night; or he may bring up troops under cover of darkness in order to make a strong attack at early dawn. As a precaution there must be an increased degree of readiness at these hours, and special patrols will be sent out beyond the line of observation.

132. The advanced portions of the outposts will habitually intrench and strengthen their positions, clear the field of fire when practicable, and open or improve communications laterally and to the rear.

Obstacles should be so placed within medium range as to delay the enemy under fire without affording him protection. Barbed wire will often be available for this purpose.

Distances to conspicuous objects in the foreground within range should be measured, or, at least paced off by experts, and the men made familiar with the ranges.

The degree of preparation of the outpost position, beyond the essentials, will depend upon the length of time it is to be occupied.