Therefore the art of the commander he regards as "economy of force" during the destructive period; that is, to employ as few troops as possible, by taking advantage of ground, cover, etc., "to use a smaller number of men in the combat with firearms than the enemy employs," so that a smaller proportionate number of his own are reduced to a "heap of cinders" and more are left, more moral force, for the decision. "Hundreds of times," he says, "a line of fire has maintained its own against one twice its strength" (_e.g._ the Boers). To do this and yet obtain a good fire-effect demands very skilful handling of the troops, both on the part of the chief and subordinate leaders. With the preponderance thus obtained the commander at last starts the decision. "Towards the close of a battle the line of retreat is always regarded with increased jealousy, therefore a threat against that line is always a potent means of bringing on the decision (Liao-yang, Mukden). On that account, when circumstances permit, the plan of battle will be aimed at that point from the very first." Or, "If this wear and tear and exhaustion of the forces has reached a certain pitch, then a rapid advance in concentrated masses on one side against the line of battle of the other" (_i.e._ the Napoleonic breaking the centre, of recent years thought almost hopeless, but revived in Manchuria with success, in the case of Nodzu breaking the centre at Mukden). From what precedes it is evident that, as in the preparatory acts, the utmost economy of forces must prevail, so in the decisive act to win the mastery through _numbers_ must be the ruling idea. Just as in the preparatory acts endurance, firmness and coolness are the first qualities, so in the decisive act boldness and fiery spirit must predominate. "The difference between these two acts will never be completely lost as respects the whole." "This is the way in which our view is to be understood; then, on the one hand, it will not come short of the reality, and on the other it will direct the attention of the leader of a combat (be it great or small, partial or general) to giving each of the two acts of activity its due share, so that there may be neither precipitation nor negligence. "_Precipitation_ there will be if space and time are not allowed for the destructive act. _Negligence_ in general there will be if a complete decision does not take place, either from want of moral courage or from a wrong view of the situation."[64] DURATION OF THE COMBAT