by J E Kaufmann
The SF of Haute Alsace, with only seven casemates and over forty blockhouses running from Sierentz to Folgensbourg and then parallel with the Swiss border, was the only sector not dependent on the Rhine as a natural barrier. Here the French established a defensive line southeast oi= Blotzheim and south along the Swiss border.
2. The Maginot Extension and Maubeuge
The Maginot Extension was part of the New Fronts built to extend the western terminus of the Maginot Line. The new ouvrages lacked some of the features of the Old Fronts and were slightly different. Some of the changes included a new type of entrance block that no longer used a rolling bridge, but a heavy metal portcullis that came up from the floor near the entrance. In addition, whereas the forts of the Maginot Line were designed to support each other and create interlocking fires, those of the extension were spaced so far apart that they could not adequately do so, not being able to assist more than one neighboring ouvrage at a time. The subsector of Marville (part of the SF of Montmedy and attached to the SF of La Crusnes when the war began) was a heavily wooded and hilly region with a number of STG casemates and other smaller positions to defend it. The 75-mm gun turret of the ouvrage of Veslones in the extension covered the entire sector. The 75-mm gun turret of the ouvrage of Fermont, the last artillery fort on the Maginot Line Proper, also covered much of this sector.
The sub-sector of Montmedy held four of the new ouvrages: two petits ouvrages, and two gros ouvrages. One of the two petits ouvrages was protected by both gros ouvrages, while the last ouvrage on the line, La Ferte, was covered only by one of the two gros ouvrages. Furthermore, the gros ouvrage were not within range of each other and could not provide mutual support. The two gros ouvrages had a single 75-mm gun turret block each. One was outfitted with an older turret of World War I vintage, and a mixed arms turret block that was basically an infantry position. Both ouvrages had several mixed arms cloches, but these forts were not as powerful as those of the main line. The petit ouvrage of Thonnelle, located between the two larger forts, had a mixed arms turret block, two other infantry blocks and an entrance block. The smallest ouvrage, at the end of the extension, was La Ferte with only two combat blocks, one of which mounted a mixed arms turret.
The main differences between the ouvrages of the main line and those of the Maginot Extension, were the extensive use of mixed arms turrets and cloches and the new and more economical type of entrance block. In addition, the artillery ouvrages were smaller in size, had fewer artillery blocks, and were not designed to support each other effectively. Finally, the petits ouvrages of the Maginot Extension were generally better armed than many of those in the Maginot Line Proper.
The New Fronts also included, among other areas, the SF of Montmedy, the SF of Maubeuge, and the lightly defended SD of the Ardennes. The SF of Maubeuge received new fortified works in 1936, after work had already begun on the New Fronts elsewhere. Four petits ouvrages were added to four old forts that partially surrounded the town of Maubeuge. Of these, three consisted of two blocks, and one of three blocks and all four included one mixed arms turret. A similar ouvrage was built in the SF of Escaut. Even though these forts are identified as Maginot ouvrages, they were of inferior quality and were even less suited to function within the Maginot scheme of defense than those of the Maginot Extension.
The ouvrages in these New Fronts included:
OUVRAGES SF of Escaut PO Eth SF of Maubeuge PO Les Sarts PO Bersillies PO Salmagne PO Le Boussois Maginot Extension PO La Ferte GO Le Chesnois POThonelle GOVeslones ENTRANCES BLOCKS 1 AM-Tur/Inf Cas, 1 Inf Cas 1 AM-Tur/Inf Cas, 1 Inf Cas _ 1 AM-Tur/Inf Cas, 1 Inf Cas 1 AM-Tur/Inf Cas, 1 Inf Cas 1 AM-Tur/Inf Cas, 2 Inf Cas 1 AM-Tur/Inf Cas, 1 Inf Cas 1 1 75-Tur, 1 AM-Tur/Inf Cas, 2 Inf Cas, 1 Obs 1` 1 AM-Tur/Inf Cas, 1 Inf Cas, 1 Obs 1 1 75-Tur, 1 AM-Tur/Inf Cas, 2 Inf Cas
NOTES: Obs=Observation and/or GFM cloches, Cas=Casemate,Tur=Turret, / = combination, lnf=lnfantry, MG=Machine Gun, 75=75-mm Gun, AM=Mixed Arms. *These entrance block served as a combat block. Cas=Casemate, Tur=Turret, / = combination, lnf=Infantry, AM=Mixed Arms
3. The Little Maginot Line (Alpine Defenses)
The Alpine or Southeastern Front included some of the most impressive Maginot fortifications. Three SFs ran from the Swiss border to the Mediterranean Sea. Mountainous terrain formed almost impenetrable gaps between the fortifications. The SFs included the following from north. to south:
The ouvrages of the SF of Savoie sealed the Arc Valley and the approaches to Modane. Other works defended the Valley of the Isere leading to Chambery. The ouvrages of the SF of Dauphine blocked the approaches to Briancon. The largest sector, the SF Alpes Maritimes, closed the southern approaches through the Maritime Alps and shielded Nice. The entrance block of its last ouvrage rested near the beach adjacent to Menton, while the rest of the ouvrage perched at a higher elevation directly above. Several more ouvrages of the SF of Alpes Maritimes actually overlooked the sea.
The Alpine ouvrages did not conform to the CORF designs of the Maginot Line Proper. In fact, they were usually smaller and held smaller garrisons. In addition, their service areas lay virtually within the combat areas. The firepower of the gros ouvrages usually equaled that of the forts of the Northeastern Front, but some petits ouvrages were more like shelters than actual combat positions.
Some ouvrages were located in hilltop positions in valleys, while others were either built into mountain sides or on mountains tops. Some had two subterranean gallery levels instead of a single level, but none had train engines since the wagons needed to be pushed only short distances. Their usines normally held three diesel engines, but did not rely on the outside electrical power grid. Because all the facilities were so close together, their entrance blocks were always of the mixed type, and were normally located close to the combat blocks. However, they were quite secure because the mountain terrain permitted much greater overhead cover than in the Maginot Line Proper. The combat blocks usually consisted of two floors and housed artillery combinations unlike similar blocks in the Northeast Front. Indeed, in the Alps it was not unusual to find an artillery block with 81-mm mortars and 75-mm guns or mortars. Many blocks had firing chambers on both levels often covering two different directions. Monte Grosso, the largest ouvrage of the Little Maginot Line, housed the only 135-mm casemate and turret in the Alps. In the SF Alpes Maritimes, Monte Grosso, L'Agaisen, and Mont Agel mounted the only 75-mm gun turrets in the Alps. The latter ouvrage had two of these turrets.
Many of the Alpine gun casemates faced forward, requiring additional concrete protection and added armor. The artillery was concentrated in two or three blocks in most cases. Turret blocks were seldom used in the Alps because the surrounding terrain did not allow a 360 degree unobstructed field of fire. Like the Maginot Line Proper, the Little Maginot Line relied on interlocking fields of fire for its defense. In most cases the terrain was so rugged that anti-tank obstacles were unnecessary, although wire obstacles remained in use.
The garrisons of the gros ouvrages averaged 160 men in the SF of Savoie, 200 men in the SF of Dauphine, and 290 men in the SF of Alpes Maritimes.
The petits ouvrages of the Southeastern Front were small and unlike similar positions in the Northeast Fronts. Normally, they mounted nothing larger than JMs and held no diesel engines. They were also classified as active abris since they seldom had more than a few cloches or embrasures and usually mounted only light weapons.
Most of the Alpine ouvrages were not finished because priority was given to the Northeast Front. In addition, the construction of such positions in the Alpine sectors involved a great deal of money because of their location and the ruggedness of the terrain. Some of the ouvrages were almost inaccessible in the winter because of the snow and in the spring because of landslides that often blocked their access roads. A few, located high in the mountains, were reached by a type of ski lift with small cable cars known as a telepherique.
The Alpine defenses also included a line of avant-postes that were, however, very different from tho
se of the Northeast. They were designed by the STG and usually built by military labor (Main d'oeuvre or MOM). Seventeen of the twentyfive avant-postes built after 1935 were sited near the frontier of the SF Alpes Maritimes. Many were multi-block and connected by trenches or tunnels, but none could be considered as strong as an ouvrage. Their main defensive advantage was in their location, since many lacked roofs over their thin walls.
In some places the advance line included upgraded older fortifications. For instance, in the early 1930s the late nineteenth-century fort of La Turra, located on a ridge dominating the pass of Mont Cenis in the SF of Savoie, received a new caserne and two gun casemates for 75-mm field pieces that opened onto the rock cliff overlooking the plateau below.
Some older fortifications to the rear of the main line were also modernized to support the newer positions. Thus the two-block gros ouvrage of Barbonnet was built into the old fort of Suchet whose old 155-mm Mougin turrets served as long range support.
The Alpine ouvrages consisted of the following:
OUVRAGES SF of Savoie PO Chatelard PO Cave a Canon GO Sapey GO Saint Gobain GO Saint Antoine GO Le Lavoir GO Pas du Roc PO Arrondaz PO Les Rochilles SF of Dauphine GOJanus PO Col du Buff ere PO Col du Granon PO Les Aittes PO Le Gondran GO Roche Lacroix GO Saint Ours Haut PO Plate Lombarde PO NW de Fontvive PO NE de Saint Ours PO Bas de Saint Ours PO Restefond PO Col de Restefond PO Granges Communes PO La Moutiere SF of Alpes Maritimes PO Col de Crous GO Rimplas PO Fressinea POValdeblore PO Col du Fort GO Gordolon GO Flaut PO Plan Caval PO La Beole PO Col d'Agnon PO La Dea GO Col de Brouis GO Monte Grosso PO Champ de tir de LAgaisen GO LAgaisen GO Saint Roch BLOCKS ENTRANCES 1 nf Cas _ _ 1 Inf Cas 1 2 75-Cas (1 gun each), 1 75-Cas, 1 Obs 1 2 81 -Cas, 2 Inf Cas, 1 Obs 1 1 75+-Cas/81-Cas, 1 Obs 2 75+-Cas, 1 75+-Cas/81-Cas, 2 Obs 2 1 1 75+-Cas, 1 81-Cas, 1 Inf Cas, 1 Obs 2 Obs 1 2 Inf Cas, 1 Obs 2 1 1 95-Cas, 1 75+Cas 181 -Cas, 2 Inf Cas, 2 Obs 1 nf Cas 1 1 1 Inf Cas, 1 Obs 1 3 Inf Cas 1 nf Cas, 1 Obs 1 1 75-Tur/75+/81 Cas, 2 Inf Cas, 2 Obs 1 1 2 81 -Cas, 1 Inf Cas, 2 Obs 1 3 Obs 2 nf Cas _ 2 Inf Cas _ 1 nf Cas _ 1 75-Cas/75+-Cas, 2 Obs _ 3 Inf Cas _ 1 Inf Cas _ 2 Inf Cas, 1 Obs _ 1 Obs _ 2 75-Cas/75+-Cas, 181 -Cas, 1 Inf Cas, 1 Obs 1 1 1 Inf Cas, 1 Obs 1 Inf Cas, 1 Obs 1 1 Inf Cas, 1 Obs _ 1 75+-Cas/81 -Cas, 181 -Cas 1 1 1 75-Cas, 2 81 -Cas, 1 Inf Cas 2 Inf Cas, 1 Obs _ 1 Obs 2 1 Obs 2 2 1 Obs 2 81-Cas 1 1 1 75-Tur, 1 75-Cas, 1 135-Tur, 1 81-Cas, 2 IN Cas 2 1 Inf Cas 1 75-Tur/81-Cas,1 75+-Cas/81-Cas, 1 Inf Cas 1 1 1 75-Cas/81 -Cas, 2 Obs GO Le Barbonnet GO Castillon PO Col des Banquettes GO Sainte Agnes PO Col des Gardes GO Mont Agel GO Roquebrune PO Croupe du Reservoir GO Cap Martin 1 1 75-Cas/81 -Cas 1 1 75-Cas/81-Cas, 181 -Cas, 2 Inf Cas 2 1 Inf Cas 1 1 135-Cas/75+/81-Cas, 75+-Cas, 1 Inf Cas 2 1 Inf Cas, 1 Obs 3 2 75-Tur, 1 Inf Cas, 1 Obs 1 2 75+-Cas/81 -Cas, 1 Inf Cas - 1 Inf Cas, 1 Obs _ 2 75-Cas, 181 -Cas
NOTES: Obs=Observation and/or GFM cloches, Cas=Casemate,Tur=Turret, / = combination, Inf=Infantry, MG=Machine Gun, 81=81-mm Mortar, 135=135-mm Howitzer, 75=75-mm Gun,75+=75-mm Mortar. Many of the ouvrages were not completed and those POs with only an entrance block completed are not listed.
4. The Coast Defenses
The French coastal defenses did not receive the same priority as the Maginot Line because it was unlikely the Germans would present a serious threat from the sea. From 1932 the 3,000 kilometers of coast line were divided into four naval districts, each commanded by an admiral. During the First World War many of the large guns were removed to be used at the front and they remained with the army after the war. Nonetheless, the French continued to maintain coastal fortifications, which were mostly concentrated in their major ports. However, with few exceptions, these installations had become obsolete before 1939.
The 1st Naval District extended from Dunkirk on the Belgian border to St. Malo, covering most of the 1,100 kilometers of the North Sea and Channel coast line. Dunkirk, Calais, and Boulogne were relatively small ports. The navy set up light defenses at Dunkirk where sand dunes and embankments dominated a large part of the coast. To the east of Dunkirk, a coastal battery and searchlight unit occupied a position north of the old Fort des Dunes (west of Zuydcoote), and further east was the Battery of Bray-Dunes. West of Dunkirk lay gun batteries at Ouvrage Ouest and at Fort Mardyck, also equipped with a searchlight. All these defenses were oriented seaward.
Further along the coast, the port of Calais included the Battery de la Digue, located opposite its West Mole and guarding the approach to the port. The ship basin on the northeast end of the town was covered by a battery and searchlight position at Bastion II. A battery at Bastion XII, defended the channel entrance toward the city in the proximity of old Fort Risban. A battery position with turret guns lay west of Calais at old Fort Lapin. In 1928 there were eight old 240-mm and 190mm guns and four railway pieces at Calais. By the beginning of the war, the defenses included no gun heavier than 120-mm. However, many weapons were in open emplacements with a 360 degree field of fire like the battery of 138-mm guns at Cap Gris Nez. The French made little effort to protect either Calais or Dunkirk from land assault. However, they did plan some water barriers for the protection of Calais.
The port of Boulogne was more extensively protected than Dunkirk or Calais. At the east end of its ship basin, north of the town, stood the gun battery of La Creche with its searchlight. Batterie de la Digue was located on the mole and Batterie du Bassin lay inside the port. Batterie du Mont de Couple, with a searchlight, and Batterie d'Alprech were on the southwest side of the town, on either side of Le Portel. Batterie d'Equilen stood about three kilometers to the south. Landward defenses were absent and the town had to rely on its old medieval walls for protection.
Further down the coast lay the two most important seaports of the 1st Naval District: Le Havre and Cherbourg. Le Havre in particular was not only an important commercial sea port, but also the key to the Seine and, therefore, to the important inland port of Rouen. The harbor of Le Havre was defended by three batteries, and the mouth of the Seine by two. Two old forts from the Vauban era overlooked the northern part of the city. In 1928 its weapons included four old 240-mm guns, two 140-mm naval guns, and two 95-mm coast guns. However, these guns may have been retired and not part of the batteries mentioned, before the war began. On the south side of the mouth of the Seine, the small harbors of Trouville and Deauville were given a battery of guns. All of these defenses overlooked the net and mine barriers installed at the mouth of the river. All these important measures were taken because the Le Havre area was considered to be one of the most important access points on the northern coast.
However, Cherbourg, which served as a naval base and headquarters for the admiral commanding the district, was the most heavily defended port in the district. Here, the moles created an inner and outer anchorage area. The outer moles linked several islands defended by forts. On the coast, up to ten kilometers east and west of the city, stood the artillery batteries. To the east lay Batterie Brulay, with its 135-mm guns and large, but still unfinished concrete observation post. There were two more batteries between Batterie Brulay and the city. Additional batteries were still under construction when the war began, including Batterie Tourville with its 340-mm Mle 1912 guns originally intended for the Normandie class battleships. Work on this position stopped in June 1940. Three others were situated west of the city. Old Fort du Roule, on the south side of the city, overlooking Cherbourg and its harbor, was one of the old Vauban positions protecting the city.
The 2nd Naval District began at St. Malo and ended south of Brest on the southwest corner of Brittany. It encompassed the easily defended major naval base of Brest, headquarters of the commander of the 2nd Naval District. Its old Vauban forts formed part of the outdated defenses of the landward and seaward fronts. However, sixteen newer battery positions protected the approaches to the anchor age outside of Brest. Not all the positions were completed in time of the war. For instance, the battery of Minou had only four of its guns. To the west of Minou lay Batterie Toulbroch with its 240-mm guns in open and unshielded concrete positions. South of the anchorage of Bres
t, on the southern end of the Crozon Peninsula, was the Batterie of Cap de la Chevre with its modem concrete command post completed in 1939. The guns of this battery, like the others, were mounted in armored shields, on pedestal positions. A mobile anti-aircraft and searchlight battery was also used. To the west of the Brittany Peninsula, the island of Ouessant served as an advance post with a gun battery on its eastern and western ends. The old fort of St. Michel, located on an island near Brest, had received two 75-mm gun turrets in 1910, one of which was still operational when the Germans incorporated the fort into their Atlantic Wall.
The 5th Naval District covered about 1,300 kilometers of Atlantic coast. It began where the 2nd Naval District ended, and continued to the Spanish frontier. The naval port of Lorient, almost defenseless in 1928, was fortified with batteries at the mouth of the river leading to the harbor. Additional defenses were being erected along this stretch of the coast when the war began.
The mouth of the Loire, leading to St. Nazaire, was covered by a battery of 194mm guns. Further down the coast La Rochelle and La Pallice were also protected by battery positions that included the batteries on the Island of Re. Batteries for 164mm and 240-mm guns were projected for Royan, at the mouth of the Gironde. Their mission would be to cover the approaches to Bordeaux. Most of these positions, including those of the 1st and 2nd Naval Districts, were improved, completed and incorporated into the German Atlantic Wall between 1942-1944.
The 3rd Naval District, which included the major seaport of Marseilles and the main naval base of Toulon, encompassed the entire Mediterranean coastline and Corsica. Marseilles, like Toulon, was heavily defended by fortifications going back to the Vauban era. In addition, it was protected by a number of coastal batteries mostly concentrated on the fortified islands of Ratonneau and Pomeque that guarded the harbor entrance. The most notable of these defenses were a 305-mm gun battery, consisting of weapons from a Danton Class battleship, located outside the port and a few 240-mm coastal guns.