Some Principles of Frontier Mountain Warfare by Wilkinson Dent Bird

Speaking generally, the procedure followed by an advanced guard may be somewhat as follows:

Both on account of considerations for its own security, and because hills will thus be more rapidly secured, it is desirable that the positions to be occupied by road picquets should, so far as it is practicable to do so from the valley, be decided some time before the main guard arrives opposite the various localities. It is also understood that considerable latitude is allowed to the picquet commander as to the position occupied, and that he is at liberty either to demand reinforcement, or to return redundant men to the advanced guard, as occasion may demand.