The task before the cavalry is here naturally quite a different one from when on the flank of the army. The necessity, or even the possibility, will in this case scarcely ever occur of having to deal with hostile cavalry, and of opening thereby a way for intervention in the decisive battle. It is much more likely in this case to happen that the cavalry will have to adopt a waiting attitude, and see whether its engagement as a mounted arm will be necessary. During this period of waiting, the cavalry must remain beyond the range of hostile fire, but as near the fighting-line as intelligent use of the ground will permit. Its position should never be chosen so far to the rear that it cannot arrive on the spot at the right time for the attack; for the moments which offer a favourable prospect for a charge are often fleeting--they depend upon the tactical situation and the moral condition of the opponent. These conditions may, however, quickly change if, for instance, reinforcements should arrive on the field. Thus, at Mars la Tour, when the 6th Cavalry Division advanced in order to attack the obviously shaken and retiring 2nd Corps of the French, it struck, according to the account of the German General Staff, not this corps, but the intact Guard Grenadier Division of Picard, which had already advanced in support, and the charge was frustrated.[41] To be prepared to meet such conditions, it will generally be advisable not only to remain as close behind the fighting-line as possible, but to prepare for a rapid deployment to the front, so that a disposition in groups, with the necessary deploying intervals, may be adopted behind that part of the fighting-line where the ground is especially adapted to a charge of large masses. If it can be seen that the crisis of the fight is approaching, and that the intervention of the cavalry may be necessary, the latter should advance still closer to the fighting-line, making, of course, full use of the ground for cover, but no longer taking heed of small losses. The cavalry will advance to the charge in order either to complete the defeat of an already wavering enemy, and to capture his artillery, or to relieve its own infantry, exhausted in the fight or suffering from want of ammunition, when other reserves have been used up, or have not yet arrived on the spot. The attack will probably always have to be conducted against an extended front. Flanking and surprise attacks will rarely be possible under such circumstances. It will scarcely ever be practicable to carry out _separate_ attacks against the hostile infantry and artillery, as in the case of a flank attack. The charge will rather, in by far the greater number of cases, first strike the hostile line of infantry, and must endeavour to ride through this and then to fall upon the enemy's artillery.