If the sappe on the glacis, along the palisadocs, or the lodgement on the crest of the covered way, has not yet been made, it must now be done. The attack should al ways be undertaken as secretly as possible; and in order to surprise the enemy, and where a lodgement on the crest of the covered way is to be constructed, this attack is to be made at midnight, that the lodgement may be finished before clay-break.
During the time the lodgement is making, and which is directed by the engineers, the men who made the assault lie down and cover themselves as securely as possible from the enemy's fire, that they may be ready to oppose the ene my if he should return, and also to protect the workmen.
As soon as it becomes light, these men retire into the lodgement, if it be ready; if not, to the next part of the trench. The lodgement is finished, if possible, the next day, if the enemy's fire is not too destructive to prevent the workmen from going on.
To prevent accidents, the men who storm the covered way are to search for the heads of small mines, and if they discover these, or any other contrivance invented by the enemy as means of annoyance, they are to be instantly de stroyed.
The attack of a covered way by mines being the most tedious, is only to be undertaken when other methods fail, or when the enemy uses mines also.
The mines must, in this case, be so constructed, that the largest globe of compression may easily burst, and that a proper tunnel or excavation may be made by it for con structing a lodgement.
The first method of attacking by mines, is to make a subterraneous well towards the covered way, of about 4 feet square, and when this has been carried to a proper distance from the third parallel, a place is to be formed for depositing the charge; the mine is then to be filled, block ed up, and fired. Experience is the best guide in deter mining the quantity of powder to be used.
In this manner the work proceeds, till it arrive near the covered way. As soon as a tunnel of a mine is formed, a lodgement is directly made there, that the troops may ad vance and take possession of it, and thus gradually approach the fortress. lf some of the enemy's mines and wells arc met with, or if his miner is heard, a mine is directly to be filled and burst, before he has time to do so with any of his.
But should the mines be destroyed by the enemy bursting his mines, new ones must he begun, which there is reason to expect will be more successful, as the enemy will then have no more mines at his command.
If the miners should chance to meet those of the enemy, a subterraneous engagement will ensue, in which smoke balls, for producing a poisonous and suffocating smoke, may be of use. If they succeed in driving the enemy out of the mines, a large one is to be made, and the whole blown up as soon as possible. In all cases it will be necessary to keep the most accurate drawing possible of the progress of the mines, executed from actual surveys.
If one of the enemy's wells be discovered, it is to be fill ed at certain spaces with quantities of powder ; these are to be blocked up properly, and the whole exploded, in order to form a lodgement or an approach, which, after bursting a mint, is finished by the sappe. In mining, it will sometimes happen that the ground is not firm enough, or that springs are met with, and that the miner is unable to proceed, in which case new wells are to be dug out, as before. The depth of these wells should, if possible, be 20 to 30 feet be low the ground. Large mines are always very advantage ous for the besieger, as they favour the construction of lodgements ; but small mines, which are not seen on the surface of the ground, are of the greatest advantage to the besieged, as they are of no use to the enemy, but serve to destroy his works, and to obstruct his advances.
The mines used to take the covered way may also be applied in destroying the traverses, and even the places of arms.
As soon as the covered way is taken, and the lodgement on it finished, the construction of the breaching batteries is begun, and, if possible, in such a way that the angle of the shoulder may be struck by the balls in a perpendicular direction. But if this cannot be clone, and if the front has a large demi-lune, the breach is to be attempted, 10 to 15 yards front the angle of the bastion.
The breach in the ravelin is made so as to destroy the intrenchments formed on it, at the same time that the breach is made ; or if this is not possible, the breach is laid 10 to 15 yards from its saliant angle.