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 produce better results than the project of some dashing subaltern, anxious for the bauble reputation. For such an attack an hour near midnight is usually selected, that the information may be gathered or the mischief done and a retreat effected under cover of darkness. A dark, wet, blustering, or--if the time be winter--an especially cold night is chosen. The degree of success to be attained depends naturally upon the element of surprise. Unless this be complete the attacking party will find their attempt usually quite futile. The other sort of attack--that which has for its object the capture of the position--is usually planned to take place during the extreme darkness just preceding daybreak. The enemy has perhaps crawled on hands and knees up the slopes towards the line of sentinels. The van of this force is composed entirely of picked men, officered by the coolest heads. Signals are agreed upon, exact times for action arranged, and everything calculated to a nicety to insure that suddenness which is the very soul of success.