If the fire power of the firing line is to be maintained after heavy losses, or the intensity of its fire is to be augmented, or when it finally is to receive the impulse for making a further advance, it must be reinforced. (Pars. 226, 227 and 341 German I. D. R.). This may be done by prolonging the line (platoons abreast at well defined intervals), or, when space is lacking and after losses have occurred, by putting men in the intervals (_i.e._, increasing the density of the line and filling it up). When the firing line is prolonged, tactical units are not broken up, and this facilitates fire control. Whenever practicable, the firing line should be reinforced by prolonging it, although the other method, that of placing men in the intervals and gaps of the firing line, is more frequently used and more practical because the arrival of fresh men and the replacement of incapacitated officers occasioned thereby renews the strength of the firing line (replenishment of ammunition). The breaking up of platoons is unavoidable, and on that account platoon and squad leaders should be trained in time of peace to form new units at once so that control is not lost. In order to prevent the mixing of units, so far as this is possible, and to keep the firing line filled up with skirmishers, even during an engagement entailing heavy losses, it is indispensable that the fighting front should be limited, that of a company in attack to 150, in defense to about 200 m. The unit designated to reinforce the firing line endeavors to approach that line under cover, forms skirmish line at any rate before leaving the last cover and advances by rushes, or, if directly in rear of the firing line and under a heavy fire, even by crawling. =Austria.= Both modes of reinforcing the firing line, that of prolonging it, and that of filling the intervals and gaps, are used. When prolonging the line the reinforcement may remain abreast of the firing line. During an attack efforts should, however, be made to advance beyond the firing line--“to overreach it.” The other method, that of filling up the line, is in attack, as a rule, to be used for the purpose of carrying the line forward, the rush to be made as soon as the reinforcement reaches the firing line. Signals are prescribed for prolonging the line without advancing beyond it, for reinforcing that line and advancing beyond it, and for filling it up and carrying it forward in a rush. (d) Closing Up. Assembling. Re-Forming. (Pars. 211-214 and 230-232 German I. D. R.).