Where his battalion is on a flank of one section of the line and a considerable interval lies between his battalion and the next section, he makes similar provision. 399. Battalion commanders in the first line establish patrols to observe and report the progress or conduct of adjoining troops when these can not be seen. FIRE SUPERIORITY. _PURPOSE AND NATURE._ 400. In a decisive battle success depends on gaining and maintaining fire superiority. Every effort must be made to gain it early and then to keep it. Attacking troops must first gain fire superiority in order to reach the hostile position. Over open ground attack is possible only when the attacking force has a decided fire superiority. With such superiority the attack is not only possible, but success is probable and without ruinous losses. Defending troops can prevent a charge only when they can master the enemy's fire and inflict heavy losses upon him. 401. To obtain fire superiority it is necessary to produce a heavy volume of accurate fire. Every increase in the effectiveness of the fire means a corresponding decrease in the effectiveness of the enemy's fire. The volume and accuracy of fire will depend upon several considerations: (_a_) _The number of rifles employed._ On a given front the greatest volume of fire is produced by a firing line having only sufficient intervals between men to permit the free use of their rifles. The maximum density of a firing line is therefore about one man per yard of front. (_b_) The _rate_ of fire affects its volume; an excessive rate reduces its accuracy. (_c_) _The character of the target_ influences both volume and accuracy. Larger dimensions, greater visibility, and shorter range increase the rate of fire; greater density increases the effect. (_d_) _Training and discipline_ have an important bearing on the rate or volume of fire, but their greatest influence is upon accuracy. The firing efficiency, of troops is reduced by fatigue and adverse psychological influences. (_e_) _Fire direction and control_ improve collective accuracy. The importance of fire direction increases rapidly with the range. Control exerts a powerful influence at all ranges. _FIRE DIRECTION AND CONTROL._ _Opening Fire._ 402. Beyond effective ranges important results can be expected only when the target is large and distinct and much ammunition is used. Long-range fire is permissible in pursuit on account of the moral effect of any fire under the circumstances. At other times such fire is of doubtful value. 403. In attack, the desire to open fire when losses are first felt must be repressed. Considerations of time, target, ammunition, and morale make it imperative that the attack withhold its fire and press forward to a first firing position close to the enemy. The attacker's target will be smaller and fainter than the one he presents to the enemy.