European military opinion generally is now more or less agreed on the following lines: The distance of detached forts from the place depends on the range of the siege artillery and the distance at which it can usually be established from the forts, and is variously The 2. Their girdle of forts must je far enough out to prevent the given by different continental writers at from 4 to 9 km. bombardment of the place. 1. Important places must be defended by fortresses. 3. An enceinte is desirable, but need not be elaborate. 4. A few guns (called "safety armament ") should be in the forts, and these must be protected by armour. 5. The bulk of the artillery of the defence should be outside the forts; the direct-fire guns preferably in cupolas, the howitzers in concealed positions. 6. The forts should be connected by lines of entrenched infantry positions and obstacles, permanent bomb-proof shelters being provided for the infantry. 7. There should be ample communications-radial and peripheral -between the place and the forts, both by road and rail. 8. Special lines of communication-such as mountain passesshould be closed by barrier forts. These considerations will now be taken somewhat more in detail, but first it will be useful to deal with the plan of Metz in 1899 (fig. 44). Here the fortifications of successive periods can be readily recognized. First the old enceinte, unaltered by the Germans and now Metz. déclassée. Next the detached forts. begun by the French engineers in 1868 and still unfinished in 1870, can be readily recognized by their bastioned trace. Among them are Fort Manteuffel, formerly St Julien, and Fort Goeben (fig. 45), formerly Queuleu. These were not altered in their general lines. forts. ring of (4500 to 10,000 yds.). The bombarding range of siege detached howitzers with heavy shells is considered to be about 8000 yds., and if it is possible for them to be eraplaced within say 2000 yds. of the forts, this would give a minimum distance of 6000 yds. from the forts to the body of the place. Some writers extend the minimum distance to 7 km., or nearly 8000 yds. In practice, however, it must happen that the position of the forts is determined to a very large extent by the lie of the ground. Thus some good positions for forts may be found within 4000 or north to Fort Alvensleben. The arrangement of wing batteries in connexion with the forts can be clearly noted at Fort Manteuffel. These are reinforced by other batteries either for the defence of the intervals or to dominate important lines of approach such as the valley of the Moselle (canal battery at Montigny). To these were added later armoured batteries. There are also infantry positions, shelters and magazines in connexion with this line. Finally some new forts of modern type were commenced in 1899 at about 9000 yds. from the place. Leaving out of consideration at present the strategic use of Fortresses, groups of fortresses, the places which, as mentioned above, are intrinsically worth being defended as fortresses are: (a) Centres of national, industrial or military resources. (e) Certain lines of communication across a frontier. Examples of (a) are Paris, Antwerp, Lyons, Verdun. Again for (a) and (b), as is pointed out by Plessix and Legrand, Metz in the hands of the Germans may serve both as a base of supplies and a point d'appui for one flank. Strassburg is a bridge-head giving the Germans a secure retreat across the Rhine if beaten in the plains of Alsace, and an opportunity of resuming the offensive when they have re-formed behind the river. From Plessix and Legrand's Manuel complet de la fortification, by permission. 5000 yds. of the place, and no others suitable on the same front within 15,000 yds. In that case the question of expense might necessitate choosing the nearer positions. Some examples of the actual distances of existing forts have already been given. Others, more recent, are, at Bucharest 7-10 km., Lyons 8-10, Copenhagen 7-8 and Paris 14-17. Strategic pivots are in a different category from other fortresses. While not necessarily protected from bombardment, they may yet have one or two forts thrown out from 9 to 12 km., to get advantage of ground. Such are Langres, Epinal and Belfort. allowed; but often it is more as a concession to tradition than for The Enceinte.-The desirability of this is almost universally any solid reason. The idea is that behind the line of forts, which is be provisionally fortified to assist in a "step-by-step" defence: and the main defensive position, any favourable points that exist should last line of defence, so that the garrison may resist to the last moment. behind these again the body of the place should be surrounded by a enceinte, such a position would not, under modern conditions, be It may be remarked that apart from the additional expense of an the most favourable for the last stages of a defence. Again, there is the difficulty that it is practically impossible to shut in a large modern town by a continuous enceinte. It has been proposed to the place. This system of course abandons several of the chief construct the enceinte in sections in front of the salient portions of advantages claimed for an enceinte. In actual practice enceintes have been constructed since 1870 in France and other countries, consisting of a simple wall 10 or 12 ft. high with a banquette and loopholes at intervals. This of course can only be looked upon as a measure of police. For war purposes, in face of modern artillery, it is a reductio ad absurdum. The Safety Armament.-If the bulk of the artillery is to be placed in positions prepared on the outbreak of war, it is considered very necessary that a few heavy long-range guns should be permanently in position ready at any moment to keep an enemy at a distance, forcing him to open his first batteries at long range and checking the secure positions inside the forts, and if they are to be worked from advance of his investment line. Such guns would naturally be in such positions they must have armour to shield them from the concentrated fire of the numerous field artillery that a besieger could bring to bear from the first. Artillery outside the forts constitutes the most important part of the defence, and there is room for much discussion as to whether it should have positions prepared for it beforehand tion of or should be placed in positions selected as the attack develops | itself. On the one hand the preparation of the positions beforeThe ques- hand, which in many cases means the use of armour and concrete, increases very largely the initial expense artillery of the defence, and ties the defender somewhat in positions. the special dispositions that become desirable once the attack has taken shape. Moreover, such expenditure must be incurred on all the fronts of the fortress, whereas the results would only be realized on the front or fronts actually attacked. On the other hand much time and labour are involved in emplacing heavy and medium artillery with extemporized protection, and this becomes a serious consideration when one remembers how much work of all kinds is necessary in preparing a fortress against attack. Again, to avoid the danger of a successful attack on the intervals between the forts before their defences have been fully completed, the fire of the guns in the intermediate positions might be urgently required. The solution in any given case would no doubt depend on the importance of the place. In most cases a certain amount of compromise will come in, some preparation being made for batteries, without their being completed. Armoured batteries of whatever kind must in any case be prepared in peace time. It should not be overlooked that as, whatever theories may exist about successive lines of defence, the onus of the defence will now lie on the fort line, just as it formerly did on the enceintes, so that line should be fully prepared, and should not have to commence its fight in a position of inequality. Defence of Intervals of Forts.-The frontal fire of the batteries in the intervals and the flanking fire of some of the guns in the forts will play an important part, but the main reliance should be on infantry defence. A fully prepared fortress would have practically a complete chain of infantry fighting positions and obstacles between the forts, at all events on the fronts likely to be seriously attacked. The positions would consist largely of fire trenches, with good communications; but it is pretty generally recognized that there Section and Elevation No.1 must be some points d'appui in the shape of redoubts or infantry forts, and also bomb-proof shelter for men, ammunition and sis near the fighting line. This is usually included in the r If they are to resist the heaviest shell, such shelters must be but in peace time. Communications are of the first importance, not merely to face required in the fighting line, but also that defenders may fully a the movement of the enormous stores of ammunition and materas the advantage of acting on interior lines. They should include Ch railways and roads running from the centre of the place to the different sectors of defence, and all round, in rear of the line of fans is essential, and where the lie of the ground does not help, it must b also ample covered approaches to the fighting line. Conceine got from earth parapets or plantations. Barria forts necessary line of communication cannot be easily diverted The principal use of barrier forts is in country where the For instance, in a comparatively flat country a barrier fort commanding a road or railway is of little use because roads may be found passing round it, or a line of railway may be diverted for some miles to avoid it. But in be necessary for the enemy to capture the fort before he can mountainous country, where such diversion is impossible, it w advance; and the impossibility of surrounding it, the tes positions from which siege artillery can be brought into play and the fact that there is practically only one road of approa to be denied, make these positions peculiarly suitable for forts with armoured batteries. Italy makes considerable use of such forts for the defence of frontier passes. General Brialmont's Theoretical Claim for the Defence of a Country -Before going into details, it is worth while to state the full clin of strategic fortification advanced by General Brialmont, the s thorough of all its advocates. It is as follows:A. Fortify the capital. B. Fortify the points where main lines of communication pass a strategic barrier. C. Make an entrenched camp at the most important centre of communication in each zone of invasion: and support it by one or two places arranged so as to make a fortified district. Section No.5 sp From Brial mont's Progrès de la défense des états el de la fortification permanente depuis Vauban, by permission of M. le Commandant G. Meeds. FIG. 47. From Brialmont's Progrès de la délense des états et de la fortification de puis Vauban, by permission of Commandant G. Meels, FIG. 48. Section No.1 Section No.5 officials of the national treasury and the commanders-in-chief of the | This parapet has no concrete shelter for the defenders. The caseactive armies. tinental thought. mates are all collected in the keep and the gorge, with a passage all round giving access to the parapet and the cupolas. Fig. 49 is a German work, Fort Molsheim at Strassburg. This is a simple type of triangular fort. The main mass of concrete rests on the gorge, and is divided by a narrow courtyard to give light and air to the front casemates. The fort has a medium armament for the artillery fight, consisting of four 6-in. howitzers in cupolas. On each face are two small Q.F. guns in cupolas for close defence, for which purpose, it will be seen, there is also an infantry parapet. At the and is defended by counterscarp galleries at the angles. There is no angles are look-out turrets. The ditch has escarp and counterscarp, covered way. The thickness of concrete over the casemates, where it is uncovered, is about 10 ft. Taking first the type of heavily armed fort, which contains guns for the artillery fight as well as safety armament, we must give precedence to General Brialmont. The two works here shown are taken from the Progrès de la défense des états, &c., published in 1898. The pentagonal fort (fig. 47) has two special features. In section I Fig. 50 is Fort Lyngby at Copenhagen. The new Copenhagen is shown a concrete infantry parapet, with a gallery in which the defences are very interesting, giving evidence of clear and original defenders of the parapet may take shelter from the bombardment thought, and effectiveness combined with economy. There is one preceding an assault. In section 2 it will be seen that the counter-special feature worth noting about the outer ring of forts, of which scarp galleries flanking the ditch are drawn back from the face of the Lyngby is one. These works are intended for the artillery fight only. counterscarp. This is to counteract proposals that have been made their main armament being four 6-in. guns (in pairs) and three 6-in. to obscure the view from the flanking galleries, and perhaps drive howitzers, all in cupolas. The armament for immediate defence is the defenders out of them by throwing smoke-producing materials into the ditch at the moment of an assault. The arrangement may save the occupants of the galleries from excessive heat and noxious fumes, but will not of course prevent the smoke from obscuring the view. The following points may be noticed about this design in comparing it with earlier types. There is no escarp, the natural slope of the rampart being carried down to the bottom of the ditch. There is a counterscarp to the faces, but no covered way. The flanks have no counterscarp, but a steel fence at the foot of the slope, and the covered way which is utilized for a wire entanglement which is under the fire of the parapet. The gorge has a very slight bastioned indentation, which allows for an efficient flanking of the ditch by a couple of machine guns placed in a single casemate on either side. The abolition of the covered way as such is noteworthy. It marks an essential difference between the fort and the old enceinte profiles; showing that offensive action is not expected from the garrison of the fort, and is the duty of the troops of the intermediate lines. The great central mass of concrete containing all the casemates and the gun-cupolas, a very popular feature, is omitted in this design, advantage being taken of the great lateral extent of the fort to spread the casemates under the faces, flanks and gorge, with a communication across the centre of the fort. This arrangement gives more freedom to the disposition of the cupolas. The thickness of the concrete over the casemate arches is more than 8 ft. Communication between the faces and the counterscarp galleries is obtained Section on AB. by posterns under the ditch. From Brialmont's Progrès de la défense des états, &c., by permission of Commandant G. Meeus. FIG. 49.-Fort Molsheim, Strassburg. powerful. It consists of two 150-mm. (6 in.) guns, four 120-mm. (4.7 in.) guns, two 210-mm. (8.4 in.) howitzers, two 210-mm. (8.4 in.) mortars, four 57-mm. Q.F. guns for close defence. There is also a shielded electric light projector in the centre. This fort is a great advance on General Brialmont's designs before 1885. These were marked by great complexity of earth parapets and various chicanes which would not long survive bombardment. This type is simple and powerful. It is also very expensive, The second Brialmont fort (fig. 48) is selected because it shows a keep or citadel, an inner work designed to hold out after the capture of the outer parapet. General Brialmont held strongly to the necessity of keeps for all important works. History of course gives instances of citadels which have enabled the garrison to recapture the main work with assistance, or caused a really useful delay in the progress of the general attack. It affords still more instances in which the keeps have made no resistance, or none of any value. Some think that the existence of a keep encourages the defenders of the main work; others that it encourages the idea of retreat. The British school of thought is against keeps. In any case they add largely to expense. In the present design the keep is a mass of concrete, which depends for the defence of its front ditches on counterscarp galleries in the main work, the few embrasures for frontal defence being practically useless. Its main function is to prevent the attackers from establishing themselves on the gorge, thus leaving the way open for a reinforcement from outside to enter (assisted by bamboo flying bridges) through the passages left for the purpose in the outer and inner gorge parapets. As regards the main work, the arrangements for defence of the ditch and the armament are similar to the design last considered. a. Cupola for Howitzer trifling, consisting of only two 57-mm. guns and a machine-gun. There is no provision for infantry defence. The ditch has no escarp or counterscarp, and is flanked by counterscarp galleries at the salient. It is usual in the case of works so slightly organized for their own defence, and intended only for the long-range artillery fight, to withdraw them somewhat from the front line. The Danish engineers, however, have not hesitated to put these works in the very front line, some 2000 metres in front of the permanent intermediate batteries. The object of this is to force the enemy to establish his heavy artillery at such long ranges that it will be able to afford little assistance to the trench attack of the infantry. The intermediate batteries, being withdrawn, are comparatively safe. They therefore do not require expensive protection, and can reserve their strength to resist the advance of the attack. The success of this arrangement will depend on the fighting strength of the cupolas under war conditions; and what that may be, war alone can tell us. In the details of these works, besides the bold cutting down of defensive precautions, we may note the skilful and economical use of layers of large stones over the casemates to diminish the thickness of concrete required. The roofs of the casemates are stiffened underneath with steel rails, and steel lathing is used to prevent lumps of concrete from falling on the occupants. The living casemates look out on the gorge, getting plenty of light and air, while the magazines are under the cupolas. The forts above described are all armed with a view to their taking an important part in the distant artillery fight. The next type to be considered (fig. 51) is selected mainly because it is a good example of the use of concealed flanking batteries, known on the continent as batteries traditores, which seem to be growing in popularity. This design by Colonel Voorduin of the Dutch engineers has a A Fig. 52, designed by the Austrian lieutenant field-marshal Moritz Ritter gilasvaiq yodavon Brunner (1839-1904), is selected as la nego oral batcaw na type of the intermediate fort which is intended only to be a strong point in the infantry line of defence between the main forts. It has a protected armament, but this, which consists only of four small Q.F. guns in cupolas, is for its own defence, and not to take part in the artillery duel. There is also a movable armament of four light Q.F. guns on wheels, for which a shelter is provided between the two observatory cupolas. The garrison would be a half company of infantry, for whom 166 casemates are provided in the gorge. The gorge ditch is flanked by a caponier, but there is no flank defence for the front ditch. This is defended by a glacis parapet. At the bottom of the ditch is a wire entanglement and the glacis slope is planted with thorns. The thickness of concrete on the casemates is 2 metres (6 ft. 7 in.). This is a strong and simple form of infantry work, but considering its rôle it appears to be needlessly expensive. From Brialmont's Progrès de la défense des états, &c., by permission of Commandant G. Meeus. From Leithner's Beständige Befestigung. FIG. 51. B |