Adam Badeau, Military history of Ulysses S. Grant from April 1861 to April 1865. Volume 2

One of the principal features of the works was the extensive use made of bomb-proofs. Owing to the great length of the lines, the same troops were often kept in the trenches for weeks, and it was necessary to give them ample protection from the weather as well as from the hostile bombardment. The bomb-proofs were long trenches cut in the ground just behind the parapets and parallel with them; the sides of these trenches were lined with rough wooden slabs, the roof was supported by uprights bearing plates, on which the cross-pieces were laid; and over these, earth was heaped to the depth required. The cross-pieces were laid close, not only for strength, but to prevent the earth from crumbling and falling through. Fireplaces and chimneys were also constructed. According to the shape of the ground, and the site, the bomb-proofs were either sunken, half sunken, or elevated; if the last, the top was sometimes used as a cavalier. In one or two places the very parapet of the main line was converted into a bomb-proof.

The general character of the fortifications was thus the same in both commands, the only important point of difference being that the batteries on the national side were absolute redoubts, while those of the enemy, south of the James, were for the most part open at the rear—a singular oversight. In all other respects the works of either army resembled those to which they were opposed. The lines of each, when seen from the advanced positions of the enemy, showed a parapet of strong profile, supported at intervals by batteries having a flanking fire to the right and left, while in front was a ditch with several rows of abatis. For months the two armies