Fortification Terminology

An elevation of earth within a fort, three or four feet wide, and less than 5 feet from the top of parapet, to enable short men to fire over the wall.

An extension at the corner of a fort consisting of two faces and two flanks. It allows the defenders of the fort to cover adjacent bastions and curtains with defensive fire. A demibastion is a small bastion that doesn’t have both faces or both flanks.

Casemate or Casement:
Bomb-proof chambers in a fort which guns are fired through windows, called embrasures.

A thin shelf stone that extends out from the walls of the fort where the parapet joins the scarp.

The wall opposite the scarp on the outside of a ditch. The counterscarp was often lined with stone blocks and mortar.

Covered Way:
The area between the ditch and the glacis. This area is protected, or “covered”, from enemy fire by the slope of the glacis.

The walls of a fort located between two bastions. Along the bastions, the curtains comprise the main walls of the fort. Another name for the main walls of a fort is scarp.

A defensive trench that prevents attackers from being able to easily attack and scale the fort walls. The walls of ditch were usually lined with stone.

An opening in the fort walls which cannons can be fired. They were often flared outward to enlarge the field of fire and could be closed with a wooden cover when not in use.

A long enclosed passageway, or corridor. Galleries ran along the base of the fort’s walls and were used as defensive positions and as a means to move around the fort without being exposed to fire.

A sloped earthen rampqart that protects the forts vertical walls from cannonfire and prevents surprise attacks. The glacis could also be covered by defensive fire from the parapets and covered way.

A small opening, usually a flared slot, through which small arms may be fired. They also were used to allow light and air to enter into the galleries and as a means to observe enemy movements safely.

A short wall of earth or stone used to protect soldiers and cannons at the top of a scarp. The parapet sits on top of the ramparts.

Place of Arms:
A protected area, usually near a sally port, in which small groups of men can be assembled when leaving or returning to the fort. Sorties, small patrols, and counter-attacks could be mounted from these areas.

A raised earthen mound or stone fortification surrounding a fort. It is usually surmounted by a parapet.

Any small fort with its own defenses which is located near a larger fort. One or more redoubts would be used as a place of last defense if the main fort should be lost.

Sally Port:
An opening in the fort’s walls that is used to enter and leave. It was often sloped downward toward the outside of the fort.

The main slope of the outer walls of the fort. The scarp is often protected from attack by a ditch and other defensive works. The wall on the opposite side of the ditch from the scarp is called the counter scarp.

A wide, angular defensive work used to protect the main entrances to a fort from cannon fire and direct assault.

The level space on the top of the ramparts on which cannons were placed. Defenders of the fort could also fire down on an enemy and use the high position of the terrplein to see approaching ships and armies.