Alpine Line

Alpine Line
Southeastern France
Block B1 at Rimplas
Type	Defensive line
Site information
Controlled by	France
Site history
Built	1930–40
In use	1935–69
Materials	Concrete, steel
Battles/wars	Italian invasion of France

The Alpine Line (French: Ligne Alpine) or Little Maginot Line (French: Petite Ligne Maginot) was the component of the Maginot Line that defended the southeastern portion of France. In contrast to the main line in the northeastern portion of France, the Alpine Line traversed a mountainous region of the Maritime Alps, the Cottian Alps and the Graian Alps, with relatively few passes suitable for invading armies. Access was difficult for construction and for the Alpine Line garrisons. Consequently, fortifications were smaller in scale than the fortifications of the main Line. The Alpine Line mounted few anti-tank weapons, since the terrain was mostly unsuitable for the use of tanks. Ouvrage Rimplas was the first Maginot fortification to be completed on any portion of the Maginot Line, in 1928. The Alpine Line was unsuccessfully attacked by Italian forces during the Italian invasion of France in 1940. Following World War II, some of the larger positions of the Alpine Line were retained in use through the Cold War.

As France studied measures to protect its northeastern frontier with Germany, a parallel effort was made to examine the improvement of France's defenses against Italy in the southeast. France's Italian border was a relic of the 1860 Treaty of Turin in which the Duchy of Savoy and the County of Nice were incorporated into France. The treaty boundary roughly followed the crest of the Maritime Alps inland through the Cottian Alps to Switzerland. The precise line of demarcation left the upper reaches of many westward-draining valleys in Italian hands, thus giving Italy positions on high points overlooking French territory, most notably Fort Chaberton on Mont Chaberton, which threatened Briançon.

The region had been extensively fortified in the seventeenth, eighteenth and nineteenth centuries, most notably by Vauban, whose fortifications of Briançon have been designated a UNESCO World Heritage Site, and by Raymond Adolphe Séré de Rivières in the late nineteenth century, who expanded the Fort de Tournoux and other fortifications in the area as part of the Séré de Rivières system of fortifications. Passage through the Alps was possible only at a series of comparatively low passes, and movement toward the major cities of southeastern France such as Lyon, Grenoble or Nice was possible only along a series of deep river valleys. Defenses therefore tended to concentrate in consistent locations: