About 12 are multivallate as distinguished by multiple ramparts, or a large counterscarp (outer bank). Around the entire complex was a moat with a protecting counterscarp. The ditch is lined with concrete on both the scarp and counterscarp faces. By early August, the besiegers had sapped within 30 paces of the counterscarp palisade. Barbed wire entanglements were swept by 77mm guns firing from bastions or counterscarp positions. On top of the counterscarp there is a parapet to provide close-in defence. There is also a counterscarp beyond the northern rampart. The penannular earthwork consist of an inner bank, a ditch and a slight counterscarp bank. A counterscarp at Fredriksten fortress is named after Ernst von Tettau. The moat was rebuilt and a counterscarp galley was built round the edge. Wherever possible, it or its highest wall is constructed on the counterscarp. Construction of the counterscarp wall, slate pavement, and "hanging shutters and doors" was still ongoing. In permanent fortifications the scarp and counterscarp may be encased in stone. There is a small counterscarp bank on the outside lip of the ditch.