An escarp wall, originally invented by Carnot, and revived by the Prussians, removed some distance to the front of the rampart; which latter, being finished exteriorly at the natural slope of the earth, remains effective after the destruction of the wall by a besieger. It was at first intended, being kept low and covered by a near counterguard, to offer extraordinary difficulties to the besieger's breaching batteries; but improved artillery has nullified that supposed advantage.