After World War Two it was expected that a future war would cost the live of many civilians. To save as many lives as possible it was decided to found the Bescherming Bevolking (Civil Protection). This service had several command posts, many of them in the large cities. However some of them were built inside existing forts. Fort Nieuwersluis, built in 1851 and between 1880 and 1882, was also used. The main barracks were modified. The facade of the first floor was covered with earth. The rooms were converted, so they could serve as a command post. They also installed a filter installation to protect the crew against a chemical and nuclear attack. The filter on the foreground could filter 10 cubic metres per hour and held 64 kg of carbon. Behind you can see the typical bicycles, used to provide fresh air in case of a power-cut.