If fifty were sufficient on the march we need a hundred during the hours of darkness. In the case of a large army an elaborate system of night guards is necessary: First, 'advanced guards', occupying strong positions at some distance from the main body; beyond these are the picket guards; further still towards the front what are called 'grand guards', from which are thrown forward the outposts, to which the line of sentinels is directly attached. In case of alarm, the sentinels fall back upon the outposts; these upon the grand guards; they, in turn, if necessary, upon the pickets; the necessities of the case and the strength of the enemy's demonstration determining the movements of the defense, even perhaps to the 'long roll' and rousing of the entire army.
In our case, no such elaborate system is possible; we content ourselves with outposts and the line of sentinels, all that will be needed, if vigilant, to guard against surprise. The colonel, attended by the officer in command of the guard, will select the sites for outposts. These, five in number, are marked by stars upon the map. The direction from which an attack is most probable is from the ridge ('R', 'R').
The men are usually on the sentinel line for two hours at a time, with opportunity for four hours' sleep; that is, with shifts, or, as they are called, 'reliefs' of three parties, two hours on and four off. This is not, however, invariable, it being sometimes wiser to relieve the men oftener or not so often, this being regulated by circumstances—the state of weather, distance of posts apart, fatigue of the men, etc., etc. The sentinels will be posted on clear nights generally upon high ground; in bad or foggy weather the foot of the slope is preferable. The officer will see that no obstacle prevents the sentinel from retreating upon his outpost if attacked. The men will be directed to take advantage of any cover that offers, always to keep in easy touch with one another and watchful, never to raise a false alarm, but quickly and decidedly a real one, and while not failing to discover the meaning of anything unusual in their front, never to expose themselves from mere bravado.
What measures shall be taken in case of an attack in force must, of course, depend entirely upon circumstances. A night attack, intended merely as an annoyance, or 'feeler', or at most to stampede some of the cattle, or to gather information as to strength, resources, etc., is quite a different affair from one planned for the purpose of complete victory, either the destruction, dispersal or capture of the command.
A mere night foray is generally executed by comparatively few. The opposing chief may be desirous of getting information concerning the force that his scouts have reported is advancing down the valley. A little expedition like ours sometimes serves as a disguise for a momentous strategical movement. The chief determines to find out all he can as to our purpose. He has found us vigilant by day; he resolves to try what the night may disclose. This sort of surprise is apt to pro-
