The French concept of defensive war had its maximum manifestation in the construction of the Maginot Line, a fortification system
running along 400 kilometers in the border from the Rhine River to Belgium, formed by three types of constructions. In the
foremost zone there was a fixed network of observation posts and first detention, anti-tank barriers, barbed wire entanglements,
machine guns and anti-tank pieces, being the whole ensemble accessible from the subsoil. Thereafter there were fortifications
which ensured a continuous obstacle to avoid penetrations. The forts were built without altering the landscape and the diverse
elements barely protruded from the ground: steel cupolas of 50 centimeters in thickness, armed with cannons of medium and large
caliber, turrets with periscopes and wells from where machine guns and cannons of small caliber emerged, being the whole ensemble
surrounded by deep lines of barbed wire entanglements, ditches and anti-tank obstracles. In the subsoil, within concrete walls of
three to four meters in thickness, they were installed the lodgings, the infirmaries, the storage rooms, the electric power
plants, the telephonic centrals, the elevators and the facilities for ventilation and heating. The third defensive system was
constituted by fortifications of an even higher size and complexity, armed with cannons of large caliber, besides those cannons
and machine guns intended for close defense. The whole system was connected through underground railways.
[1] Explosive charges for exploding the corridors
[2] Anti-tank obstacles ("dragon teeth")
[3] Heavy machine gun
[4] Anti-infantry obstacles
[5] Anti-infantry traps ("wolf holes")
[6] Light caliber cannon
[7] Armored doors
[8] Medium and heavy caliber cannons
[9] Anti-aircraft guns
[10] Main observation post
[11] Telephonic central
[12] Main command and operations room
[13] Air conditioning
[14] Generators
[15] Kitchens
[16] Troop accommodation
[17] Main storage
[18] Ammunition storage
[19] Elevators
[20] Stairs
[21] Railway
[22] Water deposit
[23] Reinforced concrete protection
[24] Infirmary
[25] Recreation and resting room
[26] Guard corps
[27] Corridor to the exterior