See Belidor’s treatise on Hydraulic Architecture.
Line of Defence, represents the flight of a musquet ball from the place where the musqueteers stand, to scour the face of the bastion. It should never exceed the reach of a musquet. It is either fichant or razant: the first is when it is drawn from the angle of the curtain to the flanked angle; the last, when it is drawn from a point in the curtain, razing the face of the bastion.
Line of Defence is the distance between the salient angle of the bastion, and the opposite flank; that is, it is the face produced to the flank. See [Fortification].
Defence of rivers, in military affairs, is a vigorous effort to prevent the enemy from passing; to effect which, a careful and attentive officer will raise redoubts, and if necessary join curtains thereto: he will place them as near the banks as possible, observing to cut a trench through the ground at the windings of the river, which may be favorable to the enemy, and to place advanced redoubts there, to prevent his having any ground fit to form on, &c. See [Rivers].
To be in a posture of Defence, is to be prepared to oppose an enemy, whether in regard to redoubts, batteries, or in the open field.
To DEFEND, to fortify, secure, or maintain a place or cause.
DEFENSE, Fr. See [Ligne de Defense].
Defense, Fr. être en défense, technically signifies to be in a state of defence, or able to resist. The French usually say: Cette redoute est en défense. This redoubt is in a state of defence.
Defenses d’une place, Fr. See Defence in [Fortification].
DEFENSIVE, serving to defend; in a state or posture of defence.