An ample stock of ready made pali sades, chevaux de frises, &c. ought to be made in time of peace, and be safely de posited, so as to be out of the reach of carcases, shells, &c.; lest they should take fire. Such machines are generally best preserved, and are safest, when immersed in water. Fascines, which are large fag gots, are dangerous in a fortress, being so soon kindled, and so prompt to get into a great blaze, as to prove highly injurious. When the the soil is sandy, or of common loam or gravel, canvas bags should be kept in reaclines to be filled, so as to stop a breach or to raise a breast-work, &c. in case of emergency.
Every endeavour should be exerted to wards obstructing the enemy from re connoitring the form of the works, as well as their disposition before the respective parts, and their defilement. The want of information as to casemated or solid de fences sometimes proves very distressing to the beseigers, who not rarely come suddenly upon works of which they had no previous information; and eventually find themselves enfiladed, or at least di rectly opposed by some masked battery ; such as the embrasures in casemated cur talus and bastions; or by redoubts within ravelines, of which they had no intelli gence, and which could not be discover ed from the glacis.
It sometimes occurs that, after getting possession of the works, the besiegers are compelled to quit the body of the place, and to retreat to their lodgments on the counterscarp. This, for the most part, is occasioned by the judicious situa tion of a citadel ; or by the peculiar mode of building the houses, &c. Indeed it has more than once happened, that, as the breach was stormed, and perhaps carried, succours have entered at some opposite part of the fortress, and enabled the gar rison to take the field with advantage. Sieges are, very frequently, raised by the approach of succours ; and many an army, thus retiring, has been either shut up, or compelled to lay down its arms.
The great variety of favourable occur. rences occasionally offering in behalf of those brave men, who, regardless of the labours, and of the painful privations to which the besciged are ever subject, con tinue firm to their duty; should stimulate each individual to the utmost exertion, and to submit to every hardship without a murmur. The example of the gover nor, and of the officers in general, rarely fails to produce that happy effect ; and, as we have so gloriously witnessed, in the case of General Elliott's defence of Gib raltar, creates an enthusiasm, that makes each man a hero ! It is in such places, and in such exigences, that the man of genius may render himself conspicuous and his name immortal ! The planning of defences in opposition to approaches, both numerous and stupendous in their con struction, and the contrivance of interior safety, as well as the means of protract ing, and of annihilating, the efforts of a numerous besieging army, composed of the flower of two nations, while they up held the brave defenders of Gibraltar to the admiration of the world, and endear ed them to their country, afford the best example, as to the duties of those who are entrusted with the defence of fortified places, and should encourage to the for mation of work after work in the interior, to prolong the doubtful contest, and to hold out to the very last moment.
Fortification, under such circumstances, is certainly a most important science; and, when duly executed, often gives a turn to the balance of war, and produces the most extraordinary reverses. ltecorsl fur nishes various instances of comparative handfuls of men having, by the aid of field-works, such as a line of redans or fieches, supported by redoubts, within musket-shot of each other ; or of swal low-tails, that is, irregularly indented lines, and various other defences, made in favourable positions; such as rising grounds, or between two deep rivers, or around a town, or among heavy woods, so completely foiled all the attempts oflarge armies, as to cause their retreat, and ulti mately their rout or dispersion. Field works are generally slight, being intend ed only for temporary defence ; they sometimes answer for the protection of convoys, and are always most formida ble when flanked by posts made in churches, mills, old castles, and a variety of such edifices. When the ground is un even, the line should run so as to occupy the most commanding spots ; at which the artillery should be principally sta tioned.
Field fortification is full of variety ; for it is perhaps scarcely possible to point out any two stations taken by an army, in the course of many and active campaigns, that would suit the same form of defence. Hence the superior ability of an engineer become conspicious. An inferior army is obliged to intrench on the strongest ground it can command, so as to check a superior and conquering enemy, advanc ing rapidly to its attack. No time is left for deep research, for consultation, for substitution, or for the correction of er rors : the thing must be done off hand ! When such is the case, the engineer must first observe the weak points, and effec tually secure them. He must then take every advantage of the strong parts; and connecting the two, so that the former shall be supported by the latter, form such a powerful range of opposition, as may at once appal the eager assailants. The knowledge of component parts, of fit proportions, and of a thousand technical requisites, are attainable by most persons of common intellect ; hut many possess a great depth of learning in these particu lars, who, nevertheless, are wanting in the indispensable qualities of quick percep tion,and of ready and appropriate decision.