The fire coming from the feature (e.g. muskets, machine-guns, case-shot etc.) sweeps along the bottom of the attendant ditch that constricts the movement of storming infantrymen to an enfilade alignment of greatest exposure and so prevents the enemy from establishing itself there. In some types of bastioned fortifications, the caponier served only as a covered means of access to the outworks, with the bastion-trace allowing for the defence of the ditch by fire from the main parapets.