Civil War Field Fortifications

Bastion Lines

A bastion was a field work very much like a lunette that consisted of two faces that formed a salient angle and two flanks that connected to curtains which were more or less straight stretches of parapet and ditch to form strong re-entering angles. A bastion's flanks were positioned to project columns of fire across the faces of collateral bastions which crossed the columns of fire projected by both the curtain between bastions and collateral bastions' faces. Bastion lines combined a series of bastions and curtains to form a continuous line of works. Each line of defense, or distance from the re-entering angle formed by the joint of a flank and curtain to the capital of the salient angle of a collateral bastion, was supposed to be no more than 160 yards long so that the entire line would be covered by close range small arms fire.

Complete bastion lines were rarely constructed during the Civil War. Though this type of line projected the most thorough network of crossing columns of fire of any of the line forms, like tenaille lines, bastion lines required a certain refined degree of geometrical symmetry that was difficult to achieve in the field over an extended position. Again like tenaille lines, bastion lines required greater depth of ground than other forms of lines and consequently required relatively more troops to adequately defend the parapet. Most manuals tended to emphasize the difficulty of properly laying out a series of bastions and the extra time, labor, and materials necessary to construct the bastions when compared to indented or redan lines. A bastion, for example, required five separate angles, two re-entering and three salient, where a redan required three (one salient, two re-entering) and a cremaillere only required one salient and one re-entering angle for each complete field work within the line.  These limitations usually restricted the use of bastions to important and appropriate points within lines that included other forms of field works.

One of the best examples of the use of multiple bastions within a continuous line occurred in the Confederate defenses of Selma, Alabama. But in this case the profile of the line was very weak with a shallow ditch and low parapet that amounted to little more than an average rifle pit. Selma's bastions, which were combined with redans to allow crossing columns of fire, inhibited the defense of the line when it was attack by Federal cavalry in 1865 by requiring more troops for a good defense than the Confederates could gather. Though the trace of Selma's defensive line seems to have been quite effective, in an abstract sense, its length and profile actually prevented the Confederates from concentrating their small garrison for a sound defensive effort while their weak profile opposed the Federal attack with an insignificant obstacle.

Note: Lunettes and bastions basically had the same shape: two faces and two flanks. Lunettes are distinguished from bastions by their use as detached works or as retired elements in continuous lines.

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