Casemates

Casemate is a fortified chamber built into a wall or as a separate vault within a fortification. In land fortifications, casemates are vaulted rooms that house artillery or serve as protected gun emplacements. They are typically integrated into curtain walls or bastions and linked by passages; their outer face carries an embrasure or gun port to fire on approaches while protecting the gun crew from direct fire. Casemates can be open to the interior of the fortress or designed as redundantly connected firing cells; they were common in medieval and early modern fortifications and remained widely used through the 19th century in masonry forts and Vauban-style systems.

In naval terms, casemate refers to an armored enclosure on a ship that protects a gun battery and allows firing through side gun ports. This arrangement preceded turret mounting in many ships and was common in ironclads and early steel battleships of the 19th century.

The word derives from the French casemate, meaning a small fortified room or house, and the concept continues to be discussed in the study of historical fortifications and museum sites.