German military maneuvers and river traffic made the population increasingly nervous, so in the spring of 1940 fortifications were erected along the borders with Germany and France.
Manuver militer Jerman dan lalu lintas sungai membuat penduduk semakin khawartir, sehingga pada musim semi tahun 1940, benteng dibangun di sepanjang perbatasan dengan Jerman dan Prancis.