Fortification Friday: “a redan or a lunette, is thrown up on the exterior to cover the outlet”

Before we close the discussion of openings for forts (see what I did there?), let me circle back to compare Mahan and Wheeler in regard to one of the fine points considered.  That being the use of a detached redan or lunette in advance of the outlet.  Recall that in pre-war writing, Mahan suggested: In