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.World War. They may be considered from two points of view: locally, as examples of a type of fortification, and collectively as a defensive ensemble.

The F este, as its name indicates, is rather a self-contained fortress on a smaller scale than a fort in the old sense. Although it forms with other such works, and with forts or batteries, part of a defensive system which as a whole may be either linear or circular, it contains within its own wire entanglements each of the elements of defence artillery for counter-battery, artillery for flanking the intervals, and infantry works for the protection of this artillery against a close attack. But it combines them in a way which differentiates it in principle from the types of fortifi- cation characteristic of the 1873-1903 epoch.

In that period there were, broadly, two opposed schools of thought, and a school of compromise. One school, fairly perhaps designated as the French, favoured an arrangement in which the " forts " form the close-defence element and intermediate bat- tery-positions the distant-defence element. The opposite, or Brialmont school, exemplified in the Liege and Namur works (see 10.698-9 for plans), relied on a simple ring of powerful self- contained forts, each including both these elements. Variations within the respective schools turned chiefly on the use or non-use of armour, some relying upon it for the protection of all defensive weapons, others confining it to the close-defence weapons and yet others excluding it altogether. The compromise school, favoured by Austrian opinion, sought to modify the characters of each type so as to combine them. In all cases, it should be added, the intervals were intended to be garnished in war with an improvised trench system, with its wire, its dugouts, and its machine-gun emplacements.

The Feste, on the contrary, attempts to combine the two ele- ments of defence without modifying either. Full security for the long-range elements is given in principle by dispersing them, equally full security for the close-defence armament by concen- tration within an obstacle. To add positive or negative pro- tection, armour is introduced wherever necessary, and loose and " provisional " as the forms may seem to the student of earlier fortification, it must not be forgotten that, structurally, every detail of the Feste is a piece of permanent work.

This very warning, however, suggests that it is necessary more necessary than ever for the student of fortification, whether practical or theoretical, to find a satisfactory answer to the question: What is it exactly that we require of " perma- nent " fortification in the tactical sphere?

The role of permanent fortification, it is suggested, is to give to the garrison or defence force a greater degree of security, and to its armament better conditions of employment, than " pro- visional," i.e. heavy field, fortification can give.

To prevent the enemy's guns from obliterating the defences of the front attacked, and thus enabling his infantry to make its way into the defended area, these guns must be counter-battered and (if possible) destroyed, but in any case neutralized as far as practicable. This implies a counter-battery armament on the side of the defence. According as the guns of this armament are exposed to enemy observation or not, they require, or they can dispense with, fighting protection. But in both cases, and es- pecially in the second, they require to be screened against hostile raids or brusque infantry assaults that may develop during this counter-battery phase, emerging perhaps from dead ground close in front.

This protection can be given in the form of an obstacle to the enemy's passage, so serious that a great and organized effort is necessary to reduce it. Such an obstacle may be a deep ditch, or a system of wire entanglements or grilles, or both. Normally, the former is the better obstacle, but except in country already intersected with canals, wet ditches, river-channels, the use of a ditch requires that the armament to be protected shall be grouped very closely. Unless, therefore, the engineer and his Government are prepared to face the expense and provide cover of the solidest kind 1 the ditch as obstacle is usually excluded, so far as concerns

1 As Col. J. C. Matheson has pointed out, the closer the grouping the denser the material required to protect it.

the protection of what may be called the main armament. The wire or grille, as compared with the ditch, is greatly inferior as an obstacle, but much more readily created, more easily destroyed, but more easily repaired also. Obstacles can be traversed, either after being broken down by bombardment in advance of the assault or by means of scaling ladders and bridges accompanying it. As against destruction by bombardment in advance, the only remedy of the defence is the counter-battery which entirely or partially stops the bombarding guns. But even without such destruction, the obstacle may be overcome by ladders and bridges, wire cutters, petards and other appropriate means, in the course of the assault itself, unless the work of placing these devices is made impossible by the defenders' fire. Hence the obstacle, whether it be ditch or wire, must be protected by a close-defence armament, and nowadays it is generally admitted that this armament must be a specialized organ. But how is this in its turn to be protected against destruction or neutralization at the critical moment? Practically by its own defensive arrangements alone. And thus, in the element designed to guard the obstacle, we reach the alternate unit of fortification upon which the whole system depends, that which in the last analysis ensures for the main armament the power of undisturbed counter-battery (in the case of a fort d'arret of keeping the forbidden area under steady fire).

The close-defence organ, then, has two functions to protect other elements and to protect itself. The former presents no particular difficulty, and is merely a question of providing the necessary fire-power. But the latter is the critical problem of modern fortification.

If the counter-battery guns are concentrated, as in a fort, and the obstacle is a ditch, then quite apart from the material cover required for these guns to enable them to fight material cover is also needed for the close-defence organ, since its position is practically obligatory. But the cover is obtained relatively easily since the weapons covered are sunk to the level of the ditch- floor, and any necessary thickness of protection can be provided over it both on first construction and later.

But such a concentration of counter-battery methods creates large intervals between work and work, and access to the defended area (which with a dispersed main armament is automatically barred by the obstacles defending this and the fire of the organ which protects them) must be prevented by organs in the works so placed as to control the open zone. In some systems reliance has been placed on the counter-battery guns themselves to do this, but modern engineer opinion generally may be said to be opposed to this, since guns which have been engaged in the artil- lery duel may have been put out of action by the time that they are wanted for close-defence, and even if intact should be wholly absorbed in their proper task. The organ providing ditch defence, by reason of its situation is not as a rule able to undertake control of the open intervals; and in short the only alternatives are small cupolas or traditore batteries. The former are open to many objections. If built into the same work as the main armament they are almost as much exposed to premature destruction as the latter is 2 and must be provided with fighting protection on the same scale. If mobile, they are exceedingly costly in proportion to the fire-power they develop. For these reasons modern practice generally favours the traditore battery, which is a casemated emplacement (sometimes a cupola) at or near ground level, giving fire only to the flanks and rear of the work, situated in the rear portion of it and protected against bombardment to a great extent by the mass of the work itself.

But, from the nature of its duty, the site of the traditore battery is frequently obligatory, and when it is combined inside the same obstacle with a concentrated counter-battery armament, the needs of the latter as to site may conflict with those of the tradi- tore. In the avoidance of this, perhaps more than in any other

2 The cupolas of this class in the Antwerp forts suffered nearly as severely as those of the main armament, although they were hardly called upon to exercise their special functions, since the infantry attack of the Germans was not pressed into the intervals before the fire of the forts had been beaten down.