The Cross Section Of A Casment. Firing Chamber Used Cartridge Trench Cannon Ammunition Hold The Cross Section And Plan Of A Casement. Concrete Roof Hook For Camouflage Netting Ventilation Duct Vertical Firing Range Concrete Foundation Sump For Streaming Water Evacuation Camouflage Netting Firing chamber Cannon Trench Ammunition hold Abutment The four casemates can be distinguished with their gun, shelters, ammunition holds and, in the foreground, the firing command post. Each artillery position, surrounded by a minefield, constituted a strong point. Firing Command Post Tobruk Or Machine Gun Emplacements Shelter And Ammunition Hold Casemates Ammunition Holds Trenches Barbed Wire Mines