As there will not often be occasion for any one to pass the chain of pickets during the night, it is a good rule (especially if the party is small), when a picket sentinel discovers any one lurking about his post from without, if he has not himself been seen, to quietly withdraw and report the fact to the commander, who can wake his men and make his arrangements to repel an attack and protect his animals. If, however, the man upon the picket has been seen, he should distinctly challenge the approaching party, and if he receives no answer, fire, and retreat to camp to report the fact.
It is of the utmost importance that picket guards should be wide awake, and allow nothing to escape their observation, as the safety of the whole camp is involved. During a dark night a man can see better himself, and is less exposed to the view of others, when in a sitting posture than when standing up or moving about. I would therefore recommend this practice for night pickets.
Horses and mules (especially the latter), whose senses of hearing and smelling are probably more acute than those of almost any other animals, will discover any thing strange or unusual about camp much sooner than a man. They indicate this by turning in the direction from whence the object is approaching, holding their heads erect, projecting their ears forward, and standing in a fixed and attentive attitude. They exhibit the same signs of alarm when a wolf or other wild animal approaches the camp; but it is always wise, when they show fear in this manner, to be on the alert till the cause is ascertained.
Mules are very keenly sensitive to danger, and, in passing along over the prairies, they will often detect the proximity of strangers long before they are discovered by their riders. Nothing seems to escape their observation; and I have heard of several instances where they have given timely notice of the approach of hostile Indians, and thus prevented stampedes.
Dogs are sometimes good sentinels, but they often sleep sound, and are not easily awakened on the approach of an enemy.
In marching with large force, unless there is a guide who knows the country, a small party should always be sent in advance to search for good camping-places, and these parties should be dispatched early enough to return and meet the main command in the event of not finding a camping-place within the limits of the day's march. A regiment should average upon the prairies, where the roads are good, about eighteen miles a day, but, if necessary, it can make 25 or even 30 miles. The advance party should therefore go as far as the command can march, provided the requisites for camping are not found within that distance. The article of first importance in campaigning is grass, the next water, and the last fuel.