ADVANCED POSTS. Positions taken up by a force in advance of the main body of an army, and in such a situation that they shall be within easy communication of it and of one another. The duties of the advanced posts are the same whether the troops are stationary or in movement. They are: (1) To keep a lookout for the enemy and when in his imme diate presence to take all means accurately to be informed of his strength, position and movements. (2) Should the enemy advance, to hold him in check long enough to give the main body ample time to be prepared for his attack. By a faithful discharge of these duties the whole army can, at all times and under all circumstances, be kept in a state of readiness for action without subjecting the soldiers to any fatigue beyond the ordinary physical en durance of a well-developed manhood; as but a small portion, comparatively, of the force present is required to watch over the, safety of the rest, and can therefore be frequently relieved, so that every one may have time suffi cient for the repose demanded after extraordi nary exertions. The object being to secure the front and flanks of the position occupied by the main body from any attempt either to reconnoitre or attack it, the detachments which form the advanced posts must be so distributed as to embrace all the avenues by which the enemy can approach the position. The system adopted, in most services, to effect this object consists of two or three concentric lines of posts, disposed in a order. The exterior line, which forms the outposts, em braces a wide circumference, and by means of a chain of sentinels, posted in advance, pre vents any one from penetrating to the rear between the posts without being seen. The
second line, which is one of grand guards, embraces a narrower circumference than the line of outposts, occupying the more important avenues from the outposts to the interior, so as to be in a position to support the outposts in case of necessity, and to receive them if driven in. The interior line consists of several strong detachments, termed pickets, posted upon the main avenues to the position. They serve as supports to the two exterior lines, upon which they rally if forced to retire before the enemy. Besides these dispositions for security, patrols are kept up between the line of posts, to keep the one informed of the state of the other; and also between the outposts and chain of sentinels, to see that the duties of the latter are well performed and to search any ground not brought well under the eyes of the sentinels. The whole, in this way, forms a connected system for observing the enemy and for mutual support in case of attack. The ground taken up by the advanced posts will depend on the capabilities which its natural features offer for defense; on the number and character of the approaches it presents to an enemy for attacking the front or flanks of the position occupied by the main body; and upon the facilities it may afford for communication between the posts.