In the last mentioned case a sudden effect, a short, powerful blow, is required, and the maximum frontage of all the units employed on the same line is admissible. But even a force advancing to the final assault can by no means dispense with distribution in depth; supports and reserves are needed to carry forward the firing line when it has been checked, to cover its flanks, and to carry on the pursuit (second line). The frontage of an organization whose flanks are secure and which is acting as a part of a larger force, depends upon other troops; considerable extension of front is admissible provided the firing line is constantly maintained at a strength which will enable it to gain a superiority of fire over the enemy. “While an organization which has only one flank protected, is less restricted as regards frontage, it will have to provide for distribution in depth on the exposed flank. In this case, it is a good plan to move the units held in rear toward the particular flank (echeloning). Interval and distance increase with the size of this echelon.” (Par. 290 German I. D. R.). The German Infantry Drill Regulations (par. 397) further emphasize the fact that, when well-trained infantry employs its rifles to good advantage in defense, it is very strong in front; that it can hold a position with a comparatively small force; and that, in this case, it has only one weak spot, the flank, which it must seek to protect by distribution in depth. This view is fully borne out by the recent events in South Africa and in Manchuria. Under favorable conditions (deliberate defense), a battalion fighting as part of a larger force may put all of its companies into the first line, a front of 200 m. being assigned to each. The battalion can thus defend a front of 800 m. The only restriction is the requirement that the battalion commander must be able, at all times, to direct the course of the combat. An organization acting alone which has to fight an action independently from beginning to end under varying conditions, cannot employ all of its available strength in the first line at one time. A distribution into three parts, viz., firing line, supports, and reserve, is therefore required. During the preparatory stage, the firing line should be as weak as possible, while, for sustaining and deciding the action, the reserve should be as strong as possible. As a rule, this distribution will not come into existence until the combat has begun; it must disappear again, during the subsequent course of the fight, through reinforcement of the troops that initiated the action, thus resulting in an increase of the combat front.