A squadron acting as advance guard would have two or three troops in reserve and one or two in support. The support would send forward as advance party two platoons, the advance party in turn sending forward as point one section. A troop acting as advance guard would have no reserve and would send forward as advance party one platoon. All Of the above may be changed as circumstances warrant.
Cases may arise when the best means of covering the head and flanks of the column will be by a line of skirmishers extended at intervals of from 5 to 50 yards, as, for instance, when passing through high corn, underbrush, etc.
It must always be remembered that the principal duty of the advance guard is to secure the uninterrupted march of the main body. If the point is fired upon, it should at once deploy and endeavor to advance fighting. The flankers should assist in this and endeavor to locate the enemy's flank should there be such resistance that advance was impossible. Each succeeding body should march promptly forward, and in turn be placed in action, with the idea of clearing the way for the advance of the main body. Should this be impossible, the commander of the entire body must determine what measures he will take.
Section 5. Rear guards.
A rear guard is a detachment detailed to protect the main body from attack in rear. Cavalry is an excellent arm for rear guard duty on account of its mobility. While part of the cavalry is using dismounted fire action, the other part may gallop back and take up a new position. In a retreat it checks pursuit and enables the main body to increase the distance between it and the enemy and to re-form if disorganized. The general formation is that of an advance guard reversed.
Its commander should take advantage of every favorable opportunity to delay the pursuers by obstructing the road, or by taking up specially favorable positions from which to force the enemy to deploy. In this latter case care must be taken not to become so closely engaged as to render withdrawal unnecessarily difficult. The position taken should be selected with reference to ease of withdrawal and ability to bring the enemy under fire at long range.
Section 6. Flank guards.
A flank guard is a detachment detailed to cover the flank of a column marching past, or across the front of, an enemy. It may be placed in position to protect the passage, or it may be so marched as to cover the passage. The object of the flank guard is to hold the enemy in check long enough to enable the main body to pass, or, like the advance guard, to enable the main body to deploy. Like all other detachments, it should be no larger than is necessary, and should not be detailed except when its protection is required.
When a flank guard consists of a regiment or less, its distance from the main body should not be much over 5 miles. Practicable communication must exist between it and the main body. The flank guard is marched as a separate command; that is, with advance or rear guards, or both, as circumstances demand, and with patrolling on the exposed flank.