In sea-coast defences, and sometimes in a land front for the defence of the ditch, embrasures are made in the scarp wall for the fire of artillery; the whole being protected from shells by a bomb-proof covering over head: this arrangement is termed a casemate.
Sometimes double ramparts and parapets are formed, so that the interior one shall fire over the more advanced; the latter in this case is called a faussebraie.
If the inner work be separated from the other it is called a retrenchment[[44]] and if in addition it has a commanding fire, it is termed, as was just remarked, a cavalier.
The term retrenchment implies an interior work, which is constructed within or in rear of another, for the purpose of strengthening it; the term intrenchment, on the contrary, implies an independent work, constructed in the open field, without reference to any other adjoining work.
The capital of a bastion is a line bisecting its salient angle. All the works comprehended between the capitals of two adjacent bastions is termed a front: it is taken as the unit in permanent fortification.
[Fig. 39] represents the ground plan of a modern bastioned front, of a regular and simple form, on a horizontal site.
![[Fig. 39]](#1647482048503906327_465.gif.id-1830894707803009299.wrap-0.html.html){kind=link}
A, A, A—Is the enceinte, or body of the place.
B—The bastions.