An examination of the arrangement of a bastioned front will show that there are neither dead-angles nor sectors without fire; that the salients, and all the ground within the range of fire, are protected by formidable columns of direct, flank and cross-fire. There is one point in this system that demands particular atten lines of defense; the extremities of the flanks are connected by curtains, CD.
In deciding on the general plan to be car ried out, the following considerations require attention: the object the work is expected to fulfill, and its situation with respect to the enemy; whether it is likely to be attacked by overwhelming forces; whether artillery is likely to be brought against it, or infantry, and whether it can be surrounded; the number of men there will be for its defense, observing that it is better to have a force concentrated, and that it is therefore injudicious to make works of a greater extent than can be well tion, which is, that the counterscar? of the ditch, if laid out parallel to the intenor crest, would form a dead-angle along each face near the shoulder; because the fire of the flank would be intercepted by the crest of the counterscarp. To prevent this, either the counterscarps of the faces must be prolonged to intersect, and all earth between them and the scarp of the flanks and curtain be exca vated, or the ditch of each face must be inclined up in a slope from the bottom, opposite the shoulder, so that it can be swept by the fire of the flank. The first method is the best, but re quires most labor; the second is chiefly objec tionable as it gives an easy access to the ditch, which might be taken advantage of in an assault.
Forts have been proposed with half-bastions, but being very little superior to the redoubt and much more difficult of construction, they ought never to be used. The exterior sides of the bastioned fort should not exceed 250 yards, nor be less than 125 yards, otherwise the flank ing arrangements, with the. smooth-bore musket in the former case, and the flanks too short in the latter, will be imperfect. With a relief of 24 feet, which is the greatest that, in most cases, can be given to field-works. and an ex
terior side of 250 yards, the ditch of the curtain will be perfectly swept by the fire of the flanks, the lines of defense will be nearly 180 yards, a length which admits of a good defense, and the flanks will be nearly 30 yards. With a relief of 14 feet, the least that will present a tolerable obstacle to ast assault, and an ex terior side of 125 yards, the ditch of the cur tain will be well flanked, the flanks will be nearly 20 yards in length, and the faces between 30 and 40 yards. Between these limits, the dimensions of the exterior side must vary with the relief.
Dutch School.—The Dutch school takes its rise in the political necessities of the times in which the nationalspirit was aroused to throw off an onerous 'foreign yoke. The aquatic character of the eou nt ry, and the want of time and pecuniary .means, led to those expedients of defense which are never wanting under like circumstances. The deficiency of earth led to the forma;ion of low parapets for the main enceinte ,and wide ditches filled with water. The main enceinte was usually preceded by a second, one with a very low parapet to sweep the surface of the wet ditch; and this second enceinte was separated from the first day by a dry ditch, which favored sorties, and which was provided with all the means, as palisades, tambours and block-houses, for offensive re turns and surprises. The second enceinte was generally covered from an exterior command by a glacis in advance of the ,main ditch. The covered-way between the glacis and the ditches was, to a great extent, deprived its essen tial offensive feature by an exterior wet ditch made at the foot of the glacis and inclosipg it, over which communication with the exterior was kept open by temporary bridges. The whole of the defensive measures of this school seem to have had solely for their object a strictly passive resistance. With this view, long lines of entrenchments, supported from dis tance to distance by forts, connected their frontier towns and villages, affording a suffi cient obstacle .to marauding expeditions, and requiring the efforts of a strong force to break through them.