Redan No. 4, Mobile

Civil War Field Fortifications

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Redan Number 4, Mobile

Mobile, Alabama was covered by three distinct lines of defensive works constructed at different times through the course of the Civil War. This field work, known as Redan Number 4, was an intermediate battery position southwest of the city of Mobile that flanked two larger bastioned works in what was known as von Sheliha's Line after the Confederate engineer who designed and oversaw construction of the line of defensive fortifications. The battery was well raised with the gun platforms 4' 6" above the natural level of the ground in rear of the work and the interior crests on the merlons raised a further 6 feet above the level of the platforms. The salient angle was rounded on two radii centered on the rear of the platforms, which improved the field of fire of the guns firing through embrasures, but restricted the defenders' ability to deliver flanking fire down the ditch in front of the salient. Each gun platform was equipped with three embrasures, which allowed the armament to be traversed almost as well as a barbette mounting while still retaining the protective cover of the merlons. Interestingly, the center embrasures for each platform were combined into one large embrasure with two throats, one for each gun, so that both guns could fire to either the right front or left front without interference.

A central traverse that was about 16 feet above the natural level, 31 feet long, and 25' 6" thick separated the two gun platforms and was quite sufficient to resist the heaviest land based artillery fire that might be expected to be brought against the work. A fully framed magazine was almost naturally placed under the traverse and between the ramps leading up to the gun platforms where it was protected by the thick parapet from horizontal fire and the large traverse from vertical fire. The 8 x 12 foot chamber with head clearance of six feet was sunken four feet below the natural level and was, understating the thing a bit, relatively spacious for a two gun battery and may have been intended to double as a bomb proof shelter for the gun crews. The gallery was formed by a sharply rising stairway that economized space and decreased its vulnerability to vertical fire by limiting the area required for the gallery entrance, which was given a form rather similar to exterior basement entrances that replace the ceiling of the stairway with the opening to the outside. A pitched transom above the entrance helped keep water running off the rear of the traverse, loose bits of soil, and other rolling debris from falling into the magazine. Doubtless the entrance was also covered by a heavy door.

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