Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/437

 simple inclosed works, such as redoubts, and in lines, the defence frequently depends on direct fire alone ; and in theso cases a work of the profile here figured with obstacles v. ould be far more effective in checking an enemy than a vork of ordinary profile without obstacles, and would render it impossible that a watchful garrison should be surprised; and this is a very important consideration, as a vigorous and bold enemy could scarcely be stopped if he had suc ceeded in arriving at the foot of the escarp unchecked. Fig. 3 exhibits another arrangement formed only of large branches securely picketed down to the ground. In this Fits, 3. Simpler arrangement of Abattis. case the form of the ground is taken advantage of, and the profile of the defensive line is modified, a trench being cut out behind it, and the banquette being formed on the surface of the ground. By simple arrangements of this kind, it will often be possible to carry defensive lines over a large extent of ground in a short period of time, and to obtain more effective defence by taking advantage of the natural facilities of the ground than by the construction, with a great expenditure of labour and time, of elevated works, not so well fitted to sweep the surface of the ground, 423 and to act upon the obstacles placed to check the progress of the assailants. Chevaiix-de-frise. The Cheval-de-frise (fig. 4) is a sub stitute for an abattis. It consists of a strong horizontal beam, 12 feet long and 9 inches square, through which are passed strong lance-like rods of wood or iron, sharp at both ends, and about G inches apart. Several of these may be joined together by rings and hooks with which the ends of the beams are fitted. Chevaux-de-frisc require a considerable amount of skilled labour in their construction ; hence they can only be em ployed in limited quantities for limited ob jects. They are employed for temporary pur poses, e.y., as barriers to the entrance of a work, across a road or street, in positions where they can be easily removed when the communication is required to be used. They have the disadvantage of being removed or destroyed with out much difficulty. It is, however, usual to keep as articles of store iron chevaux-de-frise, so made that the Fio. 4. Cheval-de-frise. pans are separable for convenience of package and trans port. If planted at the bottom of a hollow, exposed to direct fire, so that they must either be pushed uphill for- Fia. 5. Profile showing Praises on the Escarp. ward or pulled downhill backward, and securely fastened by chains to the ground or to upright posts, they form a very formidable obstacle. Fraises are palisades placed in a horizontal or nearly horizontal position. They are of wood or iron, and are usually made about 10 feet long and 15 inches thick, bound together by two ribands, nailed above and below them and buried in the ground, without which they would be more easily torn away. They are fixed both on the counterscarp and on the escarp. When on the escarp, they ; are inclined downwards, and the berm is cut away; when j on the counterscarp, they are inclined upwards. On the j counterscarp they are safe from direct fire, and retain an enemy outside the ditch. Fig. 5 represents, in section, a row of fraises on the escarp. In. this profile the ordinary banquette for musketry is repre sented by dotted lines below a wider terreplein, formed for artillery to fire over the parapet, or &quot; en barbette,&quot; as it is usually called; but this Avill be more fully explained below. The &quot; Wire Entanglement&quot; is the best and most easily made of hasty accessory defences. It can be applied everywhere, and can be made by anybody; the material of it is carried in a small compass ; it does not interfere with the fire of the defence ; it cannot be seen from a distance ; and artillery has little effect upon it. A form of wire entanglement is shown in fig. 6. Stout stakes are driven into the ground 5 feet apart, and disposed in rows FIG. G.- Wire Entanglements. chequer-wise ; strong wires are wound round them about 1 foot 6 inches above the ground, crossed diagonally by finer wires. No entanglement should be less than 3G feet in depth. The wires should hang slackly from their sup ports, as when strained they are easily divided by a sword- blow, and the stakes should vary in height. 14 B.W.G. steel wire is very suitable for the thicker wires; it is strong and weighs only 90 Ib per mile. Wire entanglements in the bottom of a ditch offer a strong resistance. They are well placed in the slopes of the glacis and counterscarp and on the berm ; but they are most effective when inter woven with bushes and trees in the defence of woods. Iron &quot; band Gabions,&quot; when disposed as in fig. 7, form a good entanglement. The bands are buttoned and placed