A Batardeau (e) is a solid piece of masonry, 7 or 8 feet thick, crossing the whole breadth of the ditch opposite the flanked angles of the bastions. It retains the water in those parts of the ditch which require to be inundated.
A Ramp (t) is a road cut in the interior slope of the rampart, forming a communication from the town, &c., to the terreplein.
A Cavalier is a work constructed upon the terreplein of a full bastion, being from 8 to 12 feet above the rampart, with a parapet 6 feet high. Its use is to command some rising ground within cannon-shot, and to serve as a traverse for preventing the neighbouring curtains from being enfiladed.
Parallels, or Places of arms, thrown up at sieges, are trenches formed to connect together the several approaches to a besieged place.
Zig-zags, or Boyeaux of communication, are trenches made for the approaches from the parallels to the besieged place. They are generally 3 feet deep, and have a parapet, and banquette.
A Redan consists of two faces forming a salient angle (which should not be less than 60°) with parapet, &c.[37]
A Lunette has two faces, similar to the redan, and also two flanks.[37]
A Redoubt is a square, polygonal, or circular field fort.[37]
A Star fort consists of a succession of salient, and re-entering angles, formed on the sides of a polygon. These forts are usually constructed on a triangle (when they have six salient points), or a square (having eight salient points).[37]
Têtes de pont, or Bridge heads, consist of redans, &c., which are constructed upon the banks of rivers, to protect the passage across them.[37]