Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/449

 FORTIFICATION 435 after taking up a position, and which, if the army does not move next day, may be strengthened in parts, according to circumstances. Continued Lines, or connected works, are resorted to in order to inclose the front of a position, or to connect im- AB varies from 180 to 400 yards. Fio. 44. Lines of Redans. portant works or forts. The most simple trace is that of redans joined together by curtains (fig. 44) ; the ditches of these curtains can only be defended by an oblique fire from the faces of the redans, but this defect may be remedied AB vanes from 300 to 600 yards. Fid. 45. Lines of Tenailles. by breaking the curtains so as to form nearly right angles with the faces of the redans, in which case they are called &quot; Lines of Tenailles&quot; (fig. 45). &quot; Lines en Cremaillere&quot; have long faces, with flanks perpendicular to them, in order to defend their ditches Fig. 46. Lines en (fig. 46). When the faces can be directed towards ground upon which it is impracticable to establish enfilading bat teries, this trace is good. Bastioned Lines (fig. 47) form the strongest trace which can be given to continued lines, when the ground will admit FIG. 47. Lines of Bastions. of its adoption. A perfectly regular trace can only be applied to level ground. The ditches in field-works are often sloped en rampe towards the adjoining flanks, in order that the &quot; deblai,&quot; or quantity of earth excavated, may not exceed the &quot; remblai,&quot; or quantity in the mass of the ram part or parapet, a condition which might otherwise occur in field-works, where there is seldom any rampart, and only cover sufficient for the defenders. Fig. 48 shows the general trace of &quot; Lines with intervals.&quot; ab varies from 200 to 500 yards. FIG. 48. Lines broken or with intervals. The salient works should never be beyond the range of musketry from the re-entering works, and the angles of defence between the two lines should be as nearly right angles as possible. &quot; Tetes-de-pont,&quot; or Bridge-heads, are works, open at the gorge, whose flanks rest upon a river, designed to cover one or more bridges. The best situation for these works is the re-entering sinuosity of a river. As Tetes-de- pont (fig. 49) are usually constructed for the purpose of en abling a retiring army to cross a river in order, and to check an enemy pressing upon it, their trace and profile should be such as to secure this double advantage to the greatest extent possible. In Sir Howard Douglas s able work on the Construction of Military Bridges will be found much valuable information upon this important subject. The obstacles which are usually added to field-works, in order to render the ap proaches more difficult to tho enemy, such as shel ter trenches, entanglements, F- 49. TGte-de-pout. palisades, barriers, abattis, trous-de-loup, chevaux-de- frise, harrows, and crows feet, have been already de scribed. Defence of Open Toicns and Villages (fig. 50). To admit of a town being advantageously intrenched it is necessary that it should not be commanded within range of field- guns, that its houses should not be of a construction easily set on fire, such as of wood with thatched roofs, and that its extent should not be out of proportion to the means and time at the disposal of the defenders. The last considera tion is of much importance and should be well weighed, as this kind of defence is prodigal of men. It is however rapidly organized ; and, as the number and the nature of the troops allotted to it are effectually concealed, it is sus ceptible of being prolonged obstinately. &quot;When time presses the first step is to occupy the outer inclosures and to bar the principal thoroughfares upon the enemy s side, to construct abattis and shelter trenches, to loophole the buildings flanking the barriers, and then to form a strong &quot;shooting line&quot; behind the outer inclosures, clearing enough of the ground in rear to receive the supports and reserves, and to enable them to act efficiently either in assist ing to expel the enemy or in covering the retreat. The approaches to the &quot; shooting line&quot; should be cleared for a distance of at least 300 yards, by levelling houses, hedges, shrubberies, filling ditches, and clearing away whatever may favour the assailants. Wood should be cut down about 2 ft. 6 in. above the ground, and with wire or other means formed into an entanglement; hedges may often be so formed into most ef fective entanglements. The squares and open places should be occupied by the main reserves; the main approaches should be subjected to artillery fire ; and distinct communications should be formed for the re treat of the defenders of the &quot; shooting line.&quot; The in- closure round the town should be completed, and for this purpose some houses should be removed, others should be loopholed, streets should be barricaded, secure places found for the magazines, and cover provided for the main supports and reserves, and wide and easy communications laterally and to the rear should be made. Streets leading out of town should be barricaded. The barricades should be sufficient to resist field artillery, and high enough not to be easily surmounted ; and they ought to be flanked by loopholing the neighbouring houses. When time presses, carts filled with dung with the wheels removed, sand-bags, bales of wool or cotton, and furniture taken from the neighbouring houses can be used as barricades. A church, a manufactory, a town-hall, a market, or any large sub stantial building should be converted into a keep, by blocking up useless entrances, loopholing its walls, and surrounding it by a ditch or abattis. Loopholes are slita or notches cut in walls with such tools as may be at hand. They are usually about 3 inches wide and 12 inches long externally, and are splayed internally so as to allow varia tion in the direction of the fire. Loopholes are cut vertically or horizontally as the case requires, and are much used as temporary means of supplementing the cover afforded by the parapets of temporary and permanent works ; they are then formed of any materials at hand, such as sand-bags, logs of wood, and brushwood. Sand-