In 1939 a commission, called Commission d'Etudes des Zones Fortifiés or Commission for the Study of Fortified Zones, was installed to design a second line. This line had to stop any breakthrough. It would consist of large blockhouses with infantry weapons. Only the construction of small parts of the second line was ever started, like near Kassel. However all the blockhouses were not finished. Here is the blockhouse near Arnecke. It should be armed with two 47 mm guns, two 8 mm machine guns and a cloche GFM. However neither of these weapons was installed.