(in French, caponniére), a structure for defensive firing designed for conducting flanking or oblique fire.

There are machine-gun, gun, and combined gun and machine-gun caponiers. In the old fortresses caponiers were designed to enfilade the moats of the fort and were placed against the inner (scarp) wall of the moat. Since World War I (1914–18) caponiers have been installed in field position systems and fortified areas. Caponiers are usually placed on rear slopes or behind a local object of the terrain for conducting artillery or machine-gun fire flanking the obstacle zone and the approaches to neighboring weapon emplacements.