Plane of Reverse Defilade

When enemy fire could pass over the interior crest of one parapet and strike the rear of another parapet the exposed parapet could be protected by either raising the parapet facing the direction of fire or by establishing a traverse (called a parados) across the parade to intercept fire that would otherwise reach the banquette of the exposed parapet. This was accomplished by establishing a plane of reverse defilade or a plane that passed from a line five feet above the highest point of ground commanding an exposed parapet to a line at least one foot above the level of the exposed parapet's interior crest. The height of the plane of reverse defilade above the interior crest of the parapet facing the direction of enemy would determine the height to which the interior crest would need to be raised to intercept enemy fire. In most cases the plane of reverse defilade passed well above the conventional limit for the height of parapets of field works (12 feet) and it was necessary to establish a parados across the parade to protect the rear of the exposed parapet.

January, 2003