Альпийская линия Мажино: Оборона юго-восточной Франции

Component of the Maginot Line
The Alpine Line 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 with the main Maginot Line of the northeast, positions took the form of concrete encased strongpoints linked by tunnels, which housed living quarters, magazines and utilities for the ouvrage. Larger ouvrages were provided with 600 narrow gauge rail lines to move materials and munitions, although unlike the northeastern positions, none were electrified. Because of the mountainous terrain and the vertical character of the sites chosen for fortification, individual blocks typically emerged from rock faces in a steep hillside or cliff with mined galleries within under rock cover. By comparison, most northeastern ouvrages were semi submerged into the gently rolling soil with galleries deeply buried beneath earth cover. In addition to the linked complexes of blockhouses that formed the grand and petit ouvrages, the country around and between each position was provided with isolated blockhouses, observation points, shelters (or abris), outposts (avants postes) and batteries, using much the same vocabulary of rounded concrete forms as the primary line of fortifications. These positions allowed the use of mobile supporting artillery, and provided rallying and control points for the necessary infantry support in the country between strongpoints, as the security of the border did not and could not depend on subterranean fortifications alone. The disposition of forward outposts, backed by heavier fortifications some kilometers to the rear, provided a defense in depth that was, in the case of the Alpine fortifications, supported by the difficult terrain.

The Alpine Line was divided into three major sectors. From north to south, they were:

Fortified Sector of Savoy (secteur fortifié de Savoie), divided into two principal sections, the Tarentaise valley around Bourg Saint Maurice, and the Maurienne valley around Modane. Fortified Sector of the Dauphiné (secteur fortifié du Dauphiné), protecting Briançon and the Ubaye Valley opposite the Col de Larche. Fortified Sector of the Maritime Alps (secteur fortifié des Alpes Maritimes), covering the Tinée and Vésubie valleys and the coast around Sospel and Menton. In addition, the area to the north of the principal fortifications was organized as the Defensive Sector of the Rhône, with virtually no fixed fortifications, since it faced neutral Switzerland. The Alpine region was under the overall command of the Army of the Alps, General René Olry in command at Valence. Its chief units were the 14th Army Corps in the SF Savoy and SF Dauphiné, and the 15th Corps in the SF Maritime Alps. Rimplas was a prototype project, not representative of other alpine or Maginot positions. CORF took over responsibility for construction in 1931, standardizing design practices, although each project was closely adapted to local circumstances. Construction was made difficult by poor access, high altitude and a short construction season. In 1931 work commenced at twenty two sites. In 1932 Ouvrage Cap Martin was sufficiently complete that it could be used in an emergency. Work continued through 1936, even though CORF had been disestablished at the end of 1935. While most of the larger positions were complete, a number of the smaller, higher altitude positions were never completed in time for war in 1940. From 1939, the main d'oeuvre Militaire (MOM) built a number of positions and blockhouses, usually in locations close to the frontier. Many of the MOM positions were incomplete in 1940. Compared with the northeastern Maginot positions, the Alpine fortifications made comparatively little use of retracting turrets, using instead concreted casemates in mountainsides surveying prepared fields of fire. The Alpine Line featured relatively few artillery ouvrages, tending instead to use mixed arms positions that combined artillery casemates and infantry positions. The main fortifications were supported by infantry shelters, or abris, of both the "passive", lightly armed type, and "active" abris with heavier armament. Some of the mountaintop gros ouvrages used aerial tramways for their primary means of access. Military roads were often constructed in the absence of existing access. All of the large positions were provided with subterranean barracks and central utility plants. Nearly all fortifications were excavated from solid rock. Coverage could therefore be reduced compared to the ouvrages of the northeast, which were at depths of up to in deep soil to resist heavy siege artillery. Independent means of power generation were a necessity in the absence of a utility distribution system. Likewise, telephone communication was problematic, with many positions using line of sight optical semaphores for communication.

Like the main Maginot Line did with the Germans, the Alpine Line achieved the goal of preventing the Italians from advancing through the protected areas. And, as the Italians had no alternative but to directly confront the fortifications, the south of France was completely protected from the Italian advance. An advance along the main coastal road was delayed by stiff resistance at the Casemate du Pont Saint Louis on the border at Menton, which was manned by seven men led by a non commissioned officer and was supported by main line fortifications at Ouvrage Cap Martin. A direct assault on Cap Saint Martin was suppressed by the ouvrage itself, supported by artillery fire from Ouvrage Mont Agel. Two more attacks were mounted, in the areas of Briançon and the Little St Bernard Pass, with little effect due to weather and the difficult terrain. Positions in the high Alps were shelled by Italian forces but were not directly attacked. Ouvrage Barbonnet traded fire with Italian positions prior to the armistice of 25 June 1940.

The Italian counterpart to the Alpine Line was Italy's Alpine Wall (Vallo Alpino), the western portions of which faced the Alpine Line across the Alpine Valleys.