4. The advance of six battalions of the IIIrd Army Corps against the =Forbach Hill= (=Spicheren=).[227] [227] _Gen. St. W._, I. p. 356. 4. DISTRIBUTION IN DEPTH AND FRONTAGE OF COMBAT FORMATIONS.[228] [228] See _Taktik_, V, _Gefechtslehre_, p. 38. The infantry combat is decided by the combined action of long firing lines. Retained forces, not launched against the enemy for the purpose of crushing him, exert no influence whatever on the decision, since they only increase losses without contributing to the fire effect. In the battles of the past, distribution in depth at the decisive stage of the combat (unless necessary as a measure of precaution, in securing the flanks, for example), was only permissible so long as the short range of the weapons allowed reserves to be kept in readiness so close to the firing line that they could assault _en masse_ at once and without any diminution of their strength. The deciding factor, which rested in retained reserves during the Napoleonic era, lies at present in the firing line.[229] [229] The French still entertain a contrary opinion. =Distribution in depth= _is, therefore, only a means to an end; an expedient made use of to maintain a dense firing line permanently at a constant strength; to give the firing line the impetus for the assault; to protect it against a reverse; and to secure its flanks. Victory is assured only by the simultaneous employment of superior fighting forces. A force should go into action in a deep combat formation, but it must extend its front during the fight._ To launch an insufficient number of troops for combat and to reinforce them gradually is a fatal error, as we are thereby compelled to fight a superior force continually with an inferior one, without being able to take advantage of the superiority which we may actually possess. The Russian attacks in the battles around =Plevna= are very instructive in this respect. On July 30th, 1877, the =Grivica= intrenchments were attacked by two columns consisting of nine battalions. The Ist and IInd Battalions of the 121st Infantry succeeded in reaching the trench, but then the attack failed. The IIIrd Battalion then attacked, with a similar result Thereupon the IInd and IIIrd Battalions of the 123rd Infantry were launched, but these also only succeeded in reaching the edge of the ditch of the trench. The attack of the left column proceeded in a similar manner, likewise that made by the reserves. An attack made simultaneously by the entire force undoubtedly would have been successful.[230] [230] _Russisch-Türkischer Krieg_ (_Gen. St. W._), German Translation, III, pp. 254 and 264.