Counterscarp
The Century Dictionary and Cyclopedia
noun.
In
fortification
, the exterior talus or slope of the ditch, or the talus that supports the earth of the covered way.
the GNU version of the Collaborative International Dictionary of English
noun.
The exterior slope or wall of the ditch; -- sometimes, the whole covered way, beyond the ditch, with its parapet and glacis.
Wiktionary, Creative Commons Attribution/Share-Alike License
noun.
The outer
slope
of a defensive or fortified
ditch
Word Usage
"The counterscarp is substantially built of plank, and spread with turf."