Adding to the Fleet.—­Naturally, the additions to the fleet will depend on the service for which the fleet is intended; that is, on the plans of strategy.  If the navy were to be gotten ready for a definite undertaking, then the additions to carry out that undertaking could be calculated and prepared; and of course this condition does come up immediately before any war occurs.  But in addition to these preparations which are to be made at the last moment (many of which cannot be made until the last moment), the staff must prepare in the leisure of profound peace for several different contingencies.  Inasmuch as many of the additions will be needed, no matter with what country the war may come; and inasmuch as the same general kind of additions will be made, it is clear that there must underlie all the various plans one general plan, to which modifications must be made to adapt it to special conditions.  And as, no matter whether we are to take the offensive or the defensive, no matter whether the fleet is to go far away or stay near our coast, the matter of additions to it is mainly a matter of degree (whether for instance ten extra colliers are needed or a hundred), it seems clear that the general plan should be the one demanding the greatest additions, so that the modifications to adapt it to special cases would consist merely in making subtractions from it.  To carry out this plan, strategy must make a sufficiently grave estimate of the situation; and logistics must make calculations to supply the most difficult demands that the estimate of the situation indicates as reasonable, and then arrange the means to provide what the calculations show.  If one has provided a little more than is necessary, it is much easier to leave out something later than it is to add more, if one has not provided enough; and one’s natural indolence then acts on the side of safety, since it tends to persuade one not to leave off too much; whereas in the opposite case, it tends to assure him that it is not really necessary to take the trouble to provide what it might be hard to get.

The Estimate of the Situation.—­In no field of strategical work is an accurate estimate of the situation more clearly necessary than when it is to form the basis for the precise calculations of logistics.  General strategical plans require a vividness of imagination and a boldness of conception that find no field for exercise in logistics; and tactics requires a quickness of decision and a forcefulness of execution that neither strategy nor logistics need; but neither strategy nor tactics calls for the mathematical exactness that logistics must have, or be of no avail.  Yet there will be no use in working out the mathematically correct means to produce certain result, if the real nature of the desired result is underrated; there will be no use in working out laboriously how many ships and tons of coal and oil are needed, if the estimate of the situation, to meet which those ships and coal and oil are needed, is inadequate.