=Division of the Position into Defensive Compartments.= We have already spoken of the sector in depth by successive lines. In the same way it is necessary to organize the positions for lateral defense. A support point may be captured by the enemy and from this ground he can launch a flanking attack on the adjacent part of the position. It is necessary that there should be an established defense against such an attack, and for this purpose each sector is divided into compartments, so to speak, with all-around defense. Boyaux or communicating trenches on the flanks of these compartments are organized as firing lines with barbed wire belts running parallel and with machine guns disposed for flanking fire. We have then each sector cut up into compartments capable of independent resistance in all directions, if the surrounding compartments are captured by the enemy. Such a compartment also has the advantage of serving as a base for a counterattack against an adjoining one that has fallen into the hands of the enemy. In a sector the responsibility of such lateral defenses falls especially upon the colonel. =Concealment.= All of the essential elements of a position, emplacements, dugouts, etc., are more or less without value if they can be seen by the enemy and subjected to heavy artillery fire. Everything that is possible must be constructed without the observation of the enemy. It is important to hide your works by making them fit in with the color scheme and shape of the surrounding ground. False or dummy trenches, emplacements, shelters, etc., are constructed to cause the enemy to waste his ammunition. The art of camouflage is also extensively employed for this purpose against both ground and aërial observation. Elements of the Organization =Plan of Organization.= We have seen that the first outline of the trenches left as a consequence of the battle must be modified in detail to obtain better protection and organization. The complete plan of reorganization is laid down by the commander of the sector and is called the Plan of Organization. This plan is drawn up as soon as the position has a permanent garrison. The Plan of Organization must be faithfully followed by all the successive garrisons of the sector. After its adoption, even the commander of the sector himself cannot modify the plan without the consent of the general in charge. The real value of the position depends upon the amount of continuous work that has been done in carrying out the original plan.