Engineers tried to build the casemates into the sides of hills or large mounds of earth in order to conceal the concrete from the enemy.
Most casemates had a concrete protection level 2 or 3. The walls which were not shielded by earth were protected by a moat (fossé in French) approximately 2m wide and 3m deep. These ditches served several purposes: they prevented an enemy from attacking embrasures and doors with explosive charges and provided space for chunks of concrete to fall into, during bombardments. This way they did not pile up and block the embrasures.
Another use for the ditch was that spend cartridges could be ejected into it. Ditches were defended by machine guns as well as special launchers to allow hand grenades to be dropped directly into the ditch.
Interval casemates were surrounded by low barb-wired entanglements.
Very often the area in front of the fortifications were further protected by anti-tank obstacles.
These consisted of six rows of steel rails set vertically in concrete. The depth was around 11.25 m. Especially in the Old Fronts, these rows were a few miles long, running through the landscape. German artillery often tried to get rid of these obstacles by means of an artillery-barrage just before an attack.
An armoured door in the rear provided acces to the casemate. One could walk through this door via a removable bridge,
crossing the ditch.
It was defended by one or two embrasures for automatic rifles: one flanking the entrance and sometimes a second inside the corridor, positioned to fire through the doorway when the door was open.