Civil War Field Fortifications
Barbette Mountings
Barbette mountings in field works allowed artillery to fire across the top of the superior slope without breaking the continuity of the parapet. During the Civil War barbettes were usually adopted for heavy artillery in specialized field works designed to concentrate two or more cannon on a relatively small front called "batteries." Only very rarely were barbettes used in field works armed solely with light artillery. Although the specific interior arrangements necessary to mount artillery en barbette depended on the type of carriage (field, barbette, siege, casemate, etc.) the cannon were mounted on, all barbette mountings in field works had some similar characteristics.
In works designed for cannon mounted on field, siege, iron barbette, or casemate carriages a platform had to be raised along the interior slope to give sufficient height to the pieces for their muzzles to clear the crest of the interior slope. Platforms for large cannon could be raised to a level four feet below the crest of the interior slope while those for light guns and howitzers could be two feet nine inches below the interior crest. Local conditions would determine the exact elevation necessary for platforms. The platform for each gun had to run at least 16 feet along the interior slope and be built inward to a distance of at 24 feet to allow cannoneers to serve the cannon without risk of falling off the raised platform. A ramp at least ten feet wide with a base to slope ratio of six to one could be constructed either at the side or rear of the platform to allow easy access to the cannon from the terre-plein. Some wooden barbette carriages raised the cannon barrel much higher than other types of carriages and allowed a corresponding reduction in the height of the platform while allowing more of the cannon crew to remain under cover of the parapet when the piece was in action.
The primary advantages of a barbette mounting were the simplicity of the battery's profile and the wider field fire that could be obtained by a piece uninhibited by the constraints of a narrow embrasure. These advantages were accompanied by the significant disadvantage of exposure to direct enemy fire. Since the parapet of a battery prepared to receive its armament mounted en barbette was much lower then that of an embrasured battery both the piece and its crew were exposed to enemy fire. This exposure became more exaggerated as the size and type of carriage decreased; the parapet of a battery designed for mounting field artillery en barbette was less than three feet high which only only provided cover for the legs of the artillerists serving the cannon. A battery prepared for artillery mounted on siege carriages would only provide cover up to the artillerists' waists. The cannon itself was exposed for the full height of its tube and liable to being dismounted or destroyed by strikes on the tube or upper portions of the carriage. It required something less than a lucky shot passing through an embrasure to dismount a barbette mounted piece: during the Federal Navy's bombardment of Fort Fisher, North Carolina, the fort's landside barbette mounted artillery suffered extensive damage and most of the guns were blasted out of action before the Federal infantry assaulted the work.
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