In fortification, a commanding ground is an area that overlooks any post, or strong place. Of this there were three sorts: first, a front commanding ground, which is a height opposite to the face of the post, which plays upon its front; second, a reverse commanding ground, which is an eminence that can play upon the back of any place or post; and third, an enfilade commanding ground, or curtain commanding ground, which is a high place, that can with its shot scour all the length of a straight line.
This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed (1728). "article name needed". Cyclopædia, or an Universal Dictionary of Arts and Sciences (first ed.). James and John Knapton, et al.
The original article can be found at Commanding ground and the edit history here.