[1177]. A palisade is a man-tight fence of posts. Round poles 4 to 6 inches in diameter at the large end are best. If the sticks run 5 to 8 inches, they may be split. If defended from the rear, palisades give some shelter from fire and the openings should be made as large as possible without letting men through. If defended from the flank, they may be closer, say 3 to 4 inches apart. The top should be pointed. A strand or two of barbed wire run along the top and stapled to each post is a valuable addition.
Palisading is best made up in panels of 6 or 8 feet length, connected by a waling piece, preferably of plank, otherwise of split stuff. If the tops are free, two wales should be used, both underground. If the tops are connected by wires, one will do.
Palisades should be planted to incline slightly to the front. As little earth should be disturbed in digging as possible, and one side of the trench should be kept in the desired plane of the palisade. If stones can be had to fit between the posts and the top of the trench, they will increase the stiffness of the structure and save time in ramming, or a small log may be laid in the trench along the outside of the posts. [Figs. 3] and [4] show the construction and placing of palisades.
[1178]. A fraise is a palisade horizontal, or nearly so, projecting from the scarp or counterscarp. A modern and better form consists of supports at 3 or 4 feet interval, connected by barbed wire, forming a horizontal wire fence. [Fig. 5].
[1179]. Cheveaux de frise are obstacles of the form shown in [Fig. 6]. They are usually made in sections of manageable length chained together at the ends. They are most useful in closing roads or other narrow passages, as they can be quickly opened for friendly troops. The lances may be of iron instead of wood and rectangular instead of round; the axial beam may be solid or composite. [Figs. 8] and [9] show methods of constructing cheveaux de frise with dimension stuff.
[1180]. A formidable obstacle against cavalry consists of railroad ties planted at intervals of 10 feet with the tops 41/2 feet above the ground, and connected by a line of rails spiked securely to each, [Fig. 7]. The rail ends should be connected by fish plates and bolted, with the ends of the bolts riveted down on the ends.
[Figs. 10] and [11] show forms of heavy obstacles employed in Manchuria by the Russians and Japanese, respectively. The former is composed of timber trestles, made in rear and carried out at night. The latter appears to have been planted in place.
[1181]. A wire entanglement is composed of stakes driven in the ground and connected by wire, barbed is the best, passing horizontally or diagonally, or both. The stakes are roughly in rectangular or quincunx order, but slight irregularities, both of position and height should be introduced.
In the high entanglement the stakes average 4 feet from the ground, and the wiring is horizontal and diagonal, [Fig. 12].