| 1. Bastions. | Besides which there are the | Right face | of bastions. |
| 2. Curtains. | Right flank | ||
| 3. Main ditch. | Left face | ||
| 4. Ravelin. | Left flank | ||
| 5. Ditch of ravelin. | Flanked angle of the bastion. | ||
| 6. Covered way. | Shoulder angle of ditto. | ||
| 7. Glacis. | Curtain angle. | ||
| 8. Tenaille. | Angle of defence. | ||
| 9. Cap. | Flanked angle of the ravelin. | ||
“We must look over this by ourselves, and then we shall make it all out, no doubt; but, now, will you tell us how so strong a place is to be taken? We want to know everything belonging to it, so please to be particular.”
“I will do my best to make you understand how a fortress is taken. You must remember one thing, that let a place be ever so strong, when closely besieged it must gradually get weaker for want of supplies; whereas the besiegers, having the country open to them, can get supplies of men, provisions, and everything else they require.”
“Ay, that gives them a great advantage.”
“There may be said to be four periods in an attack on a fortified place; the first includes all the military arrangements and preparations in the investment of the place; the second includes the opening of the trenches, or first parallel; the third includes the establishment of the second parallel; and the fourth includes the third parallel, with all the hazards and toil of seizing the covered way, of getting across the moat, and of obtaining possession, one after another, of all the works of the enemy.”
“What do you mean by the investment of the place?”
“I will tell you. When a fortified place is to be attacked, it is necessary to surround it with troops, so as to prevent the place from holding communication with, or getting supplies from their allies, or from the neighbouring country. It is often the case, too, that the besiegers form two sets of fortified lines, and pitch their camp, for security, between them. The line that faces the country is called the line of circumvallation, and the other line, facing the fortified place, is called that of countervallation; but you will understand it better by this drawing.”
“We begin to understand a little more about it now.”
“Jones, in his ‘Sieges in Spain,’ says: ‘To ensure the reduction of a fortress, a fully equipped siege army is absolutely necessary; and any deficiency, especially in the engineer or artillery departments, must assuredly involve an unnecessary loss of life; to save men, science and materials must be brought into play.’ Vauban’s invaluable maxim should ever be kept in view, ‘Never attempt anything at a siege by open force which may be gained by art and labour.’ In many cases a fortified place may be taken by investment or blockade alone, for if it be not well supplied with provisions, and cannot obtain them, it must of necessity capitulate or surrender.”