All works which are to be constructed in one night are previously determined, and proper instructions given, that they may be executed with regularity and the greatest possible dispatch. The engineers, and all overseers of the workmen, are therefore in particular to be well instructed, The first pact to be executed in the plan of an attack is the opening of the trenches, which is clone as follows. The workmen, and the men ordered to cover them, or after wards the guard of the trenches, are to collect in the most secret manner, in the evening, at some place not far dis tant from that where the attack is to be made. As soon as dark, about 200 to 300 of the best men are sent towards the fortress to•draw a line, or to compose a chain of posts parallel to the front of the attack towards the fortress. After these soldiers, who must all be men in whom the greatest confidence can be placed, and who are to be cautioned not to make the least noise, and to see that no one shall desert, follow the engineers, each at the head of a file of workmen. The latter all follow one another, observing strictly the movements of the engineer, who marches on the line which is to be dug out by his file during the night.
The workmen being thus conducted to their stations, they are carefully inspected by the engineer and his assis tants, to see that every man is in 'his place. Each then lays down his fasciae, which has previously been given him, and digs in as fast as possible behind it, the fascines being placed by the or his assistants, in such a manner as to mark the interior crest of the slope of the mount before the trenches, towards the enemy Es cry man digs in as soon as possible, to cover himse,f, in which respect they should be properly instructed by a few words from their leaders, with whom they have to march. Be hind these workmen, the rest of the guilt d of the trenches are to follow, and are placed about 20 to 30 yards distant from the workmen, who Form the first parallel.
The workmen should, if rossible, consist of soldiers, as labourers give rise to much confusion, without doing more work than an equal number of soldiers. The number of workmen is determined by the length of the line to be dug out, or when great expedition is required one foot, two teat being allowed for each man. Care is always to be taken, however, that there be not so many men as to cause con fusion, and therefore it is better to employ no more than arc absolutely necessary. All the men employed in this undertaking should be perfectly healthy, that they may not by coughing, or any other noise, alarm the garrison. They are always to be accompanied, too, by the necessai y number of officers and non-commissioned officers, to keep them in order. As soon as they are collected in the evening, the engineers divide them, each takes his number, and explains to them the nature of the work in which they are to be en gaged. The fascines and tools are then given out, and all fol low the engineer, as was before observed. In the first night, the first parallel and the approaches towards it are con structed, each engineer having a guard of from 200 to 300 men. That the engineer may have no difficulty in finding his way, the lines to be dug out are previously marked by a cord passing along a row of small poles, fixed in the lines at convenient distances. This cord may be fastened by one man after it is dark, or even at any other time ; but par ticular care must be taken that no part of the trenches can be enfiladed. If any kind of sortie or surprise is expected on the part of the garrison, the workmen must always be provided with a sufficient guard ; and that this guard, as well as all the engineers, may be better able to find their way, sometimes men arc placed at certain distances in the even ing, before it becomes dark, if that can be done without be ing discovered by the enemy. Small fires or lanthorns are
also used on some occasions with advantage.
As soon as the guard arrives at its post, or in the line which it is to occupy, it pushes a sentry towards the for tress at every ten paces, or even at a smaller distance, if necessary, who lies down, in order to observe every thing that passes in or near the place. The bulk of the guard of the trenches may be near the workmen, when an attack is expected ; but it is better to place them near the depots, and at such a distance that it may advance to support them on the first notice or alarm.
As soon as it becomes light, the workmen retire, and the guard before them also. The guard of the trenches occupies their place ; and new workmen are sent to finish such parts as have not been completed during the night. Should the enemy discover what is intended, and perceive the opening of the trenches, he will either fire at them, or attempt a sortie to attack the workmen. Should the gar rison frequently send patroles from the fortress to observe what is going on in the trenches, these patroles are to be made prisoners, if possible, without, however, firing upon them. This may be clone by a small party making a cir cuitous route, permitting the patroles of the enemy to pass, and then cutting off their retreat. Should the enemy have reason to suspect an attack, he will throw light, and fire balls, to see the besiegers, and then direct his fire at them ; but the men in the trenches will receive very little injury from this fire, as, from the circumstances under which it commences, it must be 'very uncertain. The workmen, however, will probably be frightened, and run' away. This, it' possible, is to be prevented, by representing the little danger to which they are exposed ; or, if necessary, they may be withdrawn for a certain time, till the enemy's fire ceases. If; however, the men have already proceeded so far in their digging, as to be nearly protected from the ene my's fire, they arc to continue their work, and no one is al lowed to run away or to leave his post, on any pretence whatever. Should the enemy, however, have a large gar rison, and hazard a sortie, or an attack upon the workmen or their guard, the workmen may be brought back to the places where they were collected, or to a proper distance, while the guard of the trenches advances to oppose the ene my. In such cases, cavalry to cut off the enemy's retreat should always be ready. The workmen never should be allowed to disperse, but always be kept in order; and diso bedience should be punished on the spot with death, if ne cessary. Strict discipline, added to a conciliatory mode of informing and instructing the men in their duty, will be of the utmost advantage, and is to be neglected. The workmen who come and even some of the guard of the trenches, may be usefully employed in com pleting either the communication or the parallel begun in the first night. The next morning after the opening of the trenches, the engineers inspect it, and observe whether the enemy can enflank it. Where this is the case, they order a traverse to be constructed. They also sec, that in the pa rallel the banquettes for the soldiers to fire from are pro perly constructed, and that the crest of the parapet is as nearly of the same height as possible.