In April 1915, the German High Command took an important decision that had a major impact on the work of particularly the British secret services, their representatives in the Netherlands and their Belgian spy networks. Despite the presence of border guards of the Landsturm, who patrolled the Dutch-Belgian border constantly, many smugglers, deserters, refugees and resistance couriers got through. As the border was 450km long with lots of curves and corners in a then lightly populated and forested area, it was difficult to monitor.
The fence consisted of three parts: a centrepiece that was electrified and a barbed wire fence either side of it to prevent people and animals electrocuting themselves accidentally. The electrified centrepiece was generally between 1.35m and 1.6m high and consisted of five separate wires. In some parts it was later increased to 2.5m and ten wires. In mid-July 1915, the power was put on. The current ranged from 500 to 4,000 volts or more. The voltage was not constant and it could occasionally fall out or be increased further. How many victims the so-called Death Wire claimed is unclear, but according to estimates it could have been as many as 3,000 people.