Cover may be used only to the extent that it does not interfere with constant observation of the enemy. It is not permissible to hide entirely behind cover, unless expressly ordered in each case. To rise from behind cover, for the purpose of firing, and to disappear subsequently behind that cover for loading, is out of the question in the firing line. This is physically impossible and much less attainable for psychological reasons; in addition, the skirmisher will present a much larger target than when lying down. When portions of the firing line cannot see the target during an attack, the platoon commander should consider this a hint, either to gain a better position farther to the front, or to suspend his fire temporarily. (Par. 190 German I. D. R.). In defense, in a similar case, cross fire would frequently be the proper expedient. The attacker will often see nothing except the heads of the skirmishers who must fire kneeling in order to sweep the foreground, while these men will present targets of half a man’s height to his bullets. Since smokeless powder is employed, it is important to select positions that cannot easily be found by the enemy. Positions in which the skirmishers are silhouetted against the sky line should be avoided whenever possible. Faintly illuminated targets, or those lying in the shade, are not fired on at all, according to all experience, while the fire is above all else directed against sharply outlined targets. The leaders must take to cover also, for in many cases single officers standing upright draw attention to the position. The extent of the position must be commensurate with the strength of the force; too dense a line reduces the efficacy of fire and increases the losses, while, on the other hand, too dispersed a force increases the difficulties of fire control and fire direction. 4. THE STRENGTH OF THE FIRING LINE. This depends upon the purpose of the action. Although a thin firing line may be employed when the situation is still in doubt (protection against surprise), it must be strong when the superiority of fire is to be attained. If the firing line is made too weak, we are condemned to fight a superior force continuously with an inferior one because we have voluntarily sacrificed the advantage of our numerical superiority. On the defensive, as soon as the direction of the hostile attack develops, the firing line is made as strong as seems necessary for holding the position. In a delaying action, however, we should endeavor to place as few men in action as possible; and to compensate for the lack of rifles by an increased expenditure of ammunition. All firing is done from the prone position, in so far as the ground permits. The French attempt to regulate the volume of fire by prescribing the number of rifles to be employed instead of designating the kind of fire to be used.