The French army employed them in the Maginot Line, while many were laid in the United Kingdom in 1940–1941, as part of the effort to strengthen the country's defences against a possible German invasion.
Frankrig benyttede dem i Maginot-linjen, imens mange blev benyttet i England i år 1940-1941 til at styrke det britiske forsvar imod en mulig tysk invasion.