The Maginot Line 1928–45

The line of fortifications ran roughly parallel to France’s northern border from a point near Longuyon to the Rhine River. A gap of just over 40km was left in the line astride the Sarre River south of the Saarland, the industrial border area of Germany around the city of Saarbrücken. There seem to have been several reasons why this gap, which came to be known as the Sarre Gap, was created. First, the area was low lying and had a high water table that made it unsuitable for the construction of ouvrages. Second, the Saarland was occupied by France under a provision of the Treaty of Versailles that followed World War I, and France would continue to occupy it at least until the results of a plebiscite that was to be held in 1935 were revealed. Finally, the Saarland was the only German industrial area located near the French border: should the plebiscite result in it reverting to German control and should hostilities break out between France and Germany, the Sarre Gap area was where the French Army was likely to mass for a possible offensive against Germany.

The fortifications were organised into two fortified regions, the Metz Fortified Region covering the area from Longuyon to the Sarre Gap and the Lauter Fortified Region covering the area from the Sarre Gap to the Rhine River, each of which was further divided into fortified sectors and subsectors.

The line was located 5–10km from the border. This made it possible to accurately survey likely artillery targets before the outbreak of hostilities and provided time for the garrisons to achieve full combat readiness in the unlikely event of an enemy surprise attack. Wherever possible the line followed low ridge lines. The interval casemates were situated in locations which provided optimum fields of fire and observation. The ouvrages were often situated on hilltops.