On the other hand, the practice of fortifying large towns seems now to have become obsolete. They had long lost their significance as centres of fortifications, and in future they will have such significance only as places of refuge in the midst of fortified zones. Such fortified zones will still be required, in the sense that certain frontier districts will be secured by means of a succession of permanent forts which must be constructed and maintained in time of peace, and to which must be linked certain other works to be taken in hand on the outbreak of war, and for which the necessary materials must be in readiness. It is a question of constructing not a continuous _Limites Romani_[6] which only affords a mainly immovable defence, such as was several times forced upon us by circumstances during the World War, but a succession of central points of defence, and this not in the shape of fortified towns, but of entrenchments of important areas. The World War has, as we shall explain, on the one hand confirmed anew the old truth that only by means of attack can decisive results be achieved, and that the war of movement and not entrenched warfare is the thing to be aimed at. On the other hand, it has revealed the immense power of a defence based upon well-constructed fortifications, in view of the effectiveness of modern weapons; and this revelation--more especially in view of our central geographical position--is of great value. [1] Vol. iii., p. 401. E. S. Mittler und Sohn. [2] _Einfluss der verbesserten Feuerwaffen auf die Taktik. Taktisch-strategische Aufsätze_, p. 59. [3] _Kriegsgeschichtlicke Arbeiten III. Der Italienische Feldzug des Jahres 1859_, p. 258. [4] Corr. XVIII., No. 14707. Notes sur la défense de l'Italie. [5] Corr. XIII., No. 10726. [6] The name of a continuous series of fortifications consisting of castles, walls, earthen ramparts, etc., erected by the Romans along the Rhine and the Danube, to protect their possessions from the attacks of the Germans.--_Translator's Note_. IV LEADERSHIP