by J E Kaufmann
3. The Little Maginot Line (The Alpine Defenses)
The Little Maginot Line spanned an area greater than the Maginot Line Proper, but its fortified lines actually occupied slightly less territory. In fact, almost half of the Alpine line had no fortifications, due to the forbidding nature of the terrain. This line included four major fortified positions: the first covered the city of Modane and the valley leading to the Mount Cenis Pass, the second guarded Briancon and the pass of Montgenevre, the third protected Barcelonnette, and the fourth shielded the Larche, Pourriac, and Fer passes. Finally, an almost continuous line of fortifications defended the Maritime Alps and ended on the Mediterranean, spanning about 60 to 70 kilometers. In addition, a smaller position covered the Little St. Bernard Pass, near Bourg St. Maurice, at the northern end of the Alpine sector.
4. Coast Defenses
The most important of France's inter-war coastal defenses were built on the southern tip of Corsica to defend against an Italian invasion force crossing over from Sardinia. France also created other coastal batteries in the 1920s and 1930s at key ports and had completed some modern works by 1939. The major coastal defenses guarded French harbors such as Toulon, Marseilles, Brest, and Cherbourg. Most were designed to cover the approaches to the harbors and included forts on dominating terrain overlooking the area and on islands controlling the approaches. Many of the French coastal batteries, some dating back to the eighteenth and nineteenth centuries, were later incorporated into the German Atlantic Wall.
HISTORY
After the Great War, the French High Command took a closer look at the forts of the Verdun ring, finding a number of disquieting flaws such as a lack of gas protection and proper ventilation under heavy fire. On the other hand, the old forts also had some strong points in their favor, such as the retracting turrets and the Case mates de Bourges, which had proved their worth in combat. Forts Douaumont and Vaux had demonstrated that the forts needed better infantry positions and interior defenses. Despite emphatic disclaimers on the part of the French, it appears that the German Feste, acquired with the return of Metz and Thionville, had a decided influence on the architects of the Maginot Line.
Before the Ministry of War finally made a decision regarding the type of fortifications to build, a disagreement arose between Marshal Philippe Petain and Marshal Joseph Joffre. In March 1920, the Minister of War, Andre Lefevre, directed the Conseil Superieur de la Guerre to make a study of the defensive needs of the new eastern frontier. In 1922, the War Ministry formed the Commission de Defense du Territoire (Commission of Territorial Defense) under the leadership of Joffre to further examine the problem. Joffre suggested building strong fortified positions like the ring of Verdun, but Petain insisted on lighter defenses supported by a parc mobile de fortifications (mobile park of fortifications), which could reinforce any sector and give depth to the defenses. Other commission members such as General Louis Guillaumat, Marshal Ferdinand Foch, and General Marie Debeney, who replaced a member of Petain's faction who had died in 1923, finally opted for two heavily fortified regions. In deference to Petain, a compromise solution was suggested; the defenses would form a continuous line.
In 1926, the War Ministry created the Commission de Defense des Frontieres (Border Defense Commission) under General Guillaumat, which prepared the plans for the new defensive system. At the end of the year the commission recommended three RFs on the Northeastern Front, but the third, the RF of Belfort, was soon eliminated. The commission recommended the creation of several Fortified Sectors (SFs) on the Southeastern Front to defend the likely invasion routes through the Alps. Most of the initial work for the new fortified line was undertaken by Minister of War Paul Painleve and his administration. When Andre Maginot replaced Painleve in 1929, the work was finally set into motion. The new defenses were given the name of the hero of Verdun, who was then in charge and had vigorously endorsed their creation. The Maginot Line was first planned and designed to act as a temporary shield that would hold the enemy at bay for several weeks, giving the army time to mobilize. However, early in the 1930s the original concept underwent a significant modification. The new fortifications would no longer serve as a temporary front, but would stop the enemy from advancing.
Maginot urged that the new line be completed before the French army was scheduled to withdraw from the Rhineland in 1935. By the time he became War Minister, the government had moved the pull-out date to 1930. The legislature appropriated a huge sum for the construction work in January 1930. However, by the time the line was completed the cost had soared to more than double the amount originally appropriated.
In 1927, the Commission de Defense des Frontieres set up the Commission d'Organisation des Regions Fortifiees (Commission for the Organization of the Fortified Regions or CORF) to prepare the designs for various types of fortifications. General Fillonneau, the Inspector General of Engineers, was nominated president of CORF. He appointed other officers to the commission, including representatives of the artillery and the infantry. General Belhauge replaced Fillonneau in 1929, before the actual construction began, and directed CORF until its dissolution in 1935.
In 1928 work began on Rimplas in the Alps, the first fort to be built. This led to CORF making many design changes. Full scale construction work on the Maginot Line's CORF- designed installations began in early 1930. The main priority work was on the Maginot Line Proper and the Rhine Defenses, which later were designated as the "Old Fronts" after plans were drawn up for "New Fronts." As Hitler ascended to power in 1934, a new sense of urgency arose in France for the completion and expansion of the fortifications. Unfortunately, Marshal Petain, who was the Minister of War at the time, did little to help their cause when he declared that the Ardennes were "impenetrable." In 1935, his successor began to work on the "New Fronts." By 1936, the government authorized new funds to improve the Southeastern Front when Mussolini's war with Ethiopia led to the creation of the BerlinRome Axis.
The military considered using new 145-mm guns with a range of about 29 km in turrets and the 340-mm naval guns from the Normandie Class battleships. However, these plans were indefinitely postponed, making the 75-mm gun the largest gun to be used.
The Maginot Line went on active duty in 1936, when the Germans reoccupied the Rhineland. After this crisis a number of problems, such as the organization of the garrisons and defects of design, became apparent. Since the New Fronts had not been completed by the time, and much work still needed to be done on the Maginot Line Proper and the Southeastern Front, it was possible to resolve most of these problems during the last years of the decade.
Nonetheless, a planned stop line behind the main line was never adequately completed and the linkage between the forts and the outside electrical power grid remained unfinished. Some of the weapons for the ouvrages, such as the 25-mm guns for machine gun turrets and 60-mm mortars for special bomb throwing cloches, were also not ready for installation either when the war began. Despite these shortcomings, both the Northeastern and Southeastern Fronts of the Maginot Line and their forts were practically ready for action by September 1939.
The task of protecting France's coast was turned over to the navy in 1917. However, a plan for the reorganization of the coastal gun batteries was not formulated until 1922 and was revised in 19.26. The program called for the installation in concrete emplacements of artillery from warships headed for the scrap heap. These weapons included the mostly obsolete 75-mm, 138-mm (Mle 1910), 164-mm (Mle 93-96), and 194-mm guns as well as the old 220-mm cannons. Many, especially the light weapons under 138-mm caliber, were placed in open positions with light armored shields and 360 degrees of fire.
The navy also intended to use the 305-mm guns from two older classes of battleship slated for the scrap heap, but their equipment turned out to be unsuitable. Instead it ordered the newly-designed twin gun turrets from Schneider, Mle 1924, for mounting the 340-mm guns in coastal positions since the quadruple turrets of the Normandie Class battleships were not practical for land installat
ions. Key ports received these new batteries during the 1930s.
DESCRIPTION
1. The Maginot Line
The Maginot Line included two Fortified Regions (RFs): the RF of Metz and the RF of La Lauter. Each RF had several Fortified Sectors (SFs).
The RF of Metz consisted of:
The RF of La Lauter consisted of:
The Defensive Sector (SD) of the Sarre, which occupied the gap between these two RFs, did not include any of the standard types of positions found in the RFs, except for four small artillery casemates. The sub-sectors of Kalhouse and Bining, which were part of the New Fronts built after 1935, joined the older subsector of Legeret to form the SF of Rohrbach, of the RF of Lauter.
Each SF was organized as a fortress brigade consisting of one active fortress infantry regiment and one artillery regiment. The SFs consisted of three or four sub-sectors. On mobilization the regiments quickly expanded into three regiments with the addition of reservists. At that time, a whole fortress infantry regiment would occupy each sub-sector. During mobilization, as the brigade expanded, an additional artillery regiment was formed, one or two battalions of which was assigned to each sub-sector. After September 1939, the SFs were dissolved. Some, mainly those outside of the Maginot Line Proper, were formed into fortress divisions.
The Maginot Line Proper consisted of a thin line of blockhouses and casemate positions with barbed wire and anti-tank obstacles. The ouvrages, which formed the backbone of its defenses, were far better built than the forts of Verdun, but their fire-power was not much different. The French classified the larger works as ouvrages d'artillerie (artillery ouvrages) or gros ouvrages (big ouvrages) and the smaller as petits ouvrages (small ouvrages). The former wielded the firepower of the Maginot Line while the latter, usually lacking artillery, were supplied with infantry-type support weapons.
The RFs consisted of an almost continuous line of ouvrages that covered each other with fire. The ouvrages also received support from, and in turn gave support to, the interval casemates and observatories. The abris, or infantry shelters, acted as command posts and service positions for the regiments occupying the sectors. In many cases the petits ouvrages were placed between gros ouvrages to cover gaps. In a number of places there were no artillery forts because they were not completed as originally planned and were transformed into petits ouvrages instead. This happened especially in the SFs on either side of the Sarre Gap and the SF of Haguenau on the right flank of the RF of La Lauter. The Sarre Gap was defended by positions that were mostly not designed as part of the permanent fortifications. The distinctive feature of the SD of the Sarre was its network of dams designed to create and maintain water reservoirs whose water would be released to flood the surrounding area. Most of these dams had their own defenses.
In front of the main line of defenses was an advanced line of light positions whose mission was to give early warning and delay an enemy advance. This line of avantpostes (advanced positions) usually consisted of small concrete structures for automatic weapons that, in many cases, also included road barriers and other obstacles. Fortified houses were located in this forward line, or probably even closer to the border. They usually stood in towns along the routes of advance from Germany. These houses varied in style, often consisting of a concrete bunker surmounted by a residentiallike structure. In other instances, the residential structure was attached to a bunker on one of its ends, or was sandwiched between two bunkers.
In the Maginot Line itself, the main line ouvrages occupied key terrain. CORF selected and/or designed all the positions and components of the ouvrages, casemates, abris and special blockhouses. Interval positions were placed to cover lines of advance and relay information to the forts. The interval casemates and most of the casemates of the ouvrages were oriented for flanking fires so that they could support each other. They were also designed to engage the enemy in close combat and thus were not equipped with heavy artillery.
The artillery ouvrage had a number of standard features, even though no two forts were identical. Each ouvrage consisted of two parts; the combat section and the support section. The combat section included several concrete blocks, normally of two levels, that came in several types and usually had one main function. The block types included casemate positions, turret positions, and a combination of both. In addition, each block functioned primarily as an infantry or an artillery position. In most cases the entire block was covered with earth and rock with the exception of the casemate weapons positions. Most blocks also sported a small non-movable turret, known as a cloche, that became the trademark of the Maginot Line.
The casemate blocks could be classified under two basic types, according to their function. The first was the infantry casemate position, which usually mounted a single 47-mm anti-tank gun. However, those positions built before these weapons came into production, held a smaller 37-mm anti-tank gun. The anti-tank gun shared a firing embrasure with a water-cooled twin machine gun, known as jumelage de mitrailleuse or JM. The infantry casemate sometimes had and additional position for JM or a single automatic rifle, known as Fusil Mitrailleur or FM.
Along the facade, in front of the weapons crenels, a small moat known as fosse diamant, served as a receptacle for shell casings and the gases of expended ordnance and concrete debris off the facade caused by artillery and bomb hits. Its function was to keep the firing embrasures from being blocked. A grenade launcher, or lancegrenade, ejected small grenades into the fosse to prevent the enemy from crossing it and attaching explosives to the embrasures. The fosse diamant was a standard feature on all casemates.
On the roof of the infantry casemate could be found one or more cloches that provided small-arms and mortar fire in all directions. The firing rooms were located in the upper level of this type of block, above a rest area. The roof of the infantry casemate normally consisted of 3.5 meters of concrete with an earth covering that could resist 420-mm artillery. In addition, the rear-facing wall was usually about 1.75 meters in thickness so that it could be breached by friendly heavy artillery if the position had to be recaptured.
The second type of casemate block was the artillery casemate, which usually mounted three 75-mm guns. As in most casemates, its exposed facade faced to the rear and its firing chambers were angled so that the guns covered an angle of approximately 45 degrees to the flank. Some artillery casemate blocks featured a single 135-mm howitzer-like weapon, a special type of weapon with the characteristics of a mortar and a howitzer, known as a lance-bombe. Other types of artillery blocks normally mounted a pair of 81-mm mortars, but these were usually at the lower level and fired out of the fosse. Each artillery block usually had an M-3 magazinenot found in infantry blocks-equipped. with a set of overhead rails that hauled ammunition cases in and out to the firing chambers.
In most infantry and artillery casemates, armored air vents attached to the wall drew air into the block's filter-room. In some of these blocks, an emergency exit allowed access to the surface and was used for patrolling the fort's superstructure. More commonly, however, the emergency exit opened into the fosse from the lower level. This exit was sealed by an armored door and was covered by an interior firing position for small arms. The length of the fosse was usually covered by an FM crenel. The turret blocks also came in two categories, according to their function: infantry turret blocks and artillery turret blocks. They included no more than one turret but could have several cloches. Most also had a small armored air vent that drew air into the filter room. Used air was normally expelled through the cloches. A ntonte- charge, or small lift, carried ammunition up to the turret. The turret-similar to the earlier models-had more armor, rotated 360 degrees, and eclipsed. Both eclipse and rotation operations could be carried out manually as well as electrically in all turrets. Different types of turrets were used for machine guns, 81-mm mortars, 135mm howitzers and 75-mm guns. At a later date, turrets that combined different types of weapons were added to the inventory.
The infantry turret block, included
one of three types of turrets: a machine gun turret and two types of mixed-arms turrets. The machine gun turret mounted a JM. Plans were made to add a 25-mm gun at a later date, however, this gun was not ready for mounting until the onset of the 1940 campaign. The mixed-arms turrets were developed for the New Fronts. One type mounted two JMs, each with a 25-mm gun. The other had two machine guns with a 25-mm gun. It also had a 50-mm mortar that fired through the roof even when the turret was retracted. The mixed-arms turret also included a periscope for observation. The turret was usually located in a commanding position above the block to give maximal fields of fire.
The largest turrets were located in artillery turret blocks for 75-mm guns. Like the machine gun turrets, they stood on a slight concrete rise that facilitated direct fire. The 135-mm howitzer and 81-mm mortar turrets sat in a small concrete depression to reduce their silhouette since these weapons used a high trajectory. The shells from the 75-mm gun and 135-mm howitzers were returned to the lower level in turrets and casemates through a funnel or hopper known as an entonnoir, into a toboggan, ending in a storage area inside the fort. All the artillery turrets mounted two weapons, but only the 75-mm turret had an observation position. In addition to the turrets, the ouvrage had cloches that came in several types and sizes. The GFM (Guet and Fusil Mitrailleur or observation and automatic rifle) was the most common type. It came in various sizes but normally had three or four crenels and special mounts for an episcope, an FM, and a special 50-mm breech-loaded mortar. Most cloche types also had a roof mounting for a small observation periscope. Access was by a ladder, but in most cloches the floor could also be raised and lowered. The cloches served as an exit for the fort's filtered air. The rush of air leaving the block made such a din that it was difficult to hear in cloches, besides being drafty and uncomfortable. The greatest weakness of these cloches was that they usually towered above the block, and, unless they were heavily camouflaged, they were quite vulnerable to direct enemy fire.