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. The advanced guard may move in the following order. First a vanguard of one or more companies, preceding the remainder by about half a mile, and adapting its formation to the ground. Then the mainguard, at the head of which should be the advanced guard commander, his staff officer, the battalion commander of the unit furnishing the leading company, and the company commander. [Illustration] As the troops march up the valley, the advanced guard commander should decide what localities are to be held, and in what strength. He should issue his orders to the battalion or company commander, as the case may be, when the picquets should move direct to their positions. Meanwhile, the staff officer should make, in sections, a rough sketch of the positions occupied by the various picquets, which should be numbered consecutively as they move out, the sections of the sketch being sent, as completed, to the officer commanding the rear-guard. In addition, to insure that no picquet is overlooked by the rear-guard, a double sentry, with a paper showing the number of its picquet, should be placed in the roadway beneath the height occupied, and it is the duty of the picquet commander to keep in touch with this sentry post. In this manner the roadway should be picquetted, until the locality is reached where the column is to halt, when the advanced guard commander should take the usual measures for the security of the camp, for safe-guarding the water supply, etc. It has been suggested that an advanced guard should be divided into two portions, advanced guard, and the picquetting troops, each under a separate leader, the object being to free the advanced guard commander from the work of picquetting, so that his whole attention can be devoted to tactics. The advanced guard is to clear the hills, which are then to be occupied by picquets. This system does not appear sound, for it necessitates two men doing the work of one, and, in practice, the advanced guard usually either meets with little or no resistance, or with such serious opposition that picquetting is in abeyance. Each picquet, when it reaches the position selected by its leader, should intrench, taking especial care to provide head cover, so that the enemy may not be easily able to observe the moment of its final withdrawal.