マジノ線
The Maginot Line was invulnerable to aerial bombings and tank fire and had underground railways as a backup; it also had state-of-the-art living conditions for garrisoned troops, supplying air conditioning and eating areas for their comfort. French and British officers had anticipated the geographical limits of the Maginot Line; when Germany invaded the Netherlands and Belgium, they carried out plans to form an aggressive front that cut across Belgium and connected to the Maginot Line.