Maginot Line

There are 142 ouvrages, 352 casemates, 78 shelters, 17 observatories and around 5,000 blockhouses in the Maginot Line.[lower-alpha 1]

There are several kinds of armoured cloches. Cloches are non-retractable turrets. The word cloche is a French term meaning bell due to its shape. All cloches were made of alloy steel.

• The most widespread are the GFM cloches, where GFM means Guetteur fusil-mitrailleur (machine-gun sentry). They are composed of three to four openings, called crenels or embrasures. These crenels may be equipped as follows: light machine-guns, direct vision blocks, binoculars blocks or 50 mm (2.0 in) mortars. Sometimes, the cloche is topped by a periscope. There are 1,118 GFM cloches on the line. Almost every block, casemate and shelter is topped by one or two GFM cloches.
• The JM cloches (jumelage de mitrailleuses or "twin machine guns") are the same as the GFM cloches except that they have one opening equipped with a pair of machine guns. There are 174 JM cloches on the line.
• There are 72 AM cloches (armes mixtes or "mixed weapons") on the line, equipped with a pair of machine guns and a 25 mm (1.0 in) anti-tank gun. Some GFM cloches were transformed into AM cloches in 1934. (The aforementioned total does not include these modified cloches.)
• There are 75 LG cloches (lance-grenade or "grenade launcher") on the line. Those cloches are almost completely covered by concrete, with only a small hole to launch grenades through for local defence.
• There are 20 VP cloches (vision périscopique or "periscopic vision") on the line. These cloches could be equipped with several different periscopes. Like the LG cloches, they were almost entirely covered by concrete.
• The VDP cloches (vision directe et périscopique or "direct and periscopic vision") are similar to the VP cloches but have two or three openings to provide a direct view. Consequently, they were not covered by concrete.

• 
  GFM cloche
• 
  JM cloche
• 
  AM cloche
• 
  LG cloche
• 
  VP cloche
• 
  VDP cloche

The line included the following retractable turrets.

• 21 turrets of 75 mm (3.0 in) model 1933
• 12 turrets of 75 mm (3.0 in) model 1932
• 1 turret of 75 mm (3.0 in) model 1905
• 17 turrets of 135 mm (5.3 in)
• 21 turrets of 81 mm (3.2 in)
• 12 turrets for mixed weapons (AM)
• 7 turrets for mixed weapons + mortar of 50 mm (2.0 in)
• 61 turrets of machine-guns

• 
  75 mm (3.0 in) Turret model 1932
• 
  135 mm (5.3 in) Turret
• 
  81 mm (3.2 in) Turret
• 
  Machine-gun Turret
• 
  AM (Mixed-Weapons) Turret

Both static and mobile artillery units were assigned to defend the Maginot Line. Régiments d'artillerie de position (RAP) consisted of static artillery units. Régiments d'artillerie mobile de forteresse (RAMF) consisted of mobile artillery.[11]

• Canon de 25 mm SA Mle1934
• SA-L Mle1937 (Puteaux) L/72

The Maginot Line

The defences were first proposed by Marshal Joseph Joffre. He was opposed by modernists such as Paul Reynaud and Charles de Gaulle, who favoured investment in armour and aircraft. Joffre had support from Marshal Henri Philippe Pétain, and the government organised many reports and commissions. André Maginot finally convinced the government to invest in the scheme. Maginot was another veteran of World War I; he became the French Minister of Veteran Affairs and then Minister of War (1928–1932).

In January 1923, after Weimar Germany defaulted on reparations, the French Premier Raymond Poincaré responded by sending French troops to occupy Germany's Ruhr region. During the ensuing Ruhrkampf ("Ruhr struggle") between the Germans and the French that lasted until September 1923, Britain condemned the French occupation of the Ruhr. A period of sustained Francophobia broke out in Britain, with Poincaré being vilified in Britain as a cruel bully punishing Germany with unreasonable reparations demands. The British—who openly championed the German position on reparations—applied intense economic pressure on France to change its policies towards Germany. At a conference in London in 1924 to settle the Franco-German crisis caused by the Ruhrkampf, the British Prime Minister Ramsay MacDonald successfully pressed the French Premier Édouard Herriot to make concessions to Germany. The British diplomat Sir Eric Phipps, who attended the conference, commented afterwards that:

The London Conference was for the French 'man in the street' one long Calvary as he saw M. Herriot abandoning one by one the cherished possessions of French preponderance on the Reparations Commission, the right of sanctions in the event of German default, the economic occupation of the Ruhr, the French-Belgian railway Régie, and finally, the military occupation of the Ruhr within a year.[12]

The great conclusion that was drawn in Paris after the Ruhrkampf and the 1924 London Conference was that France could not make unilateral military moves to uphold Versailles as the resulting British hostility to such moves was too dangerous to the republic. Beyond that, the French were well aware of the contribution of Britain and its dominions to the victory of 1918. French decision-makers believed they needed Britain's help to win another war; the French could only go so far with alienating the British.[13] From 1871 forward, French elites had concluded that France had no hope of defeating Germany on its own, and France would need an alliance with another great power to defeat the Reich.[14]

In 1926, The Manchester Guardian ran an exposé showing the Reichswehr had been developing military technology forbidden by the Treaty of Versailles in the Soviet Union. The secret German-Soviet cooperation started in 1921.[15] The German statement following The Manchester Guardian's article that Germany did not feel bound by the terms of Versailles and would violate them as much as possible gave much offence in France. Nonetheless, in 1927, the Inter-Allied Commission, which was responsible for ensuring that Germany complied with Part V of the Treaty of Versailles, was abolished as a goodwill gesture reflecting the "Spirit of Locarno".[16] When the Control Commission was dissolved, the commissioners in their final report issued a blistering statement, stating that Germany had never sought to abide by Part V and the Reichswehr had been engaging in covert rearmament all through the 1920s. Under the Treaty of Versailles, France was to occupy the Rhineland region of Germany until 1935. Still, the last French troops left the Rhineland in June 1930 in exchange for Germany accepting the Young Plan.[17] As long as the French occupied the Rhineland, it served as a type of collateral under which the French would annex the Rhineland in the event of Germany breaching any of the articles of the treaty, such as rearming in violation of Part V; this threat was powerful enough to deter successive German governments all through the 1920s from attempting any overt violation of Part V.[18] French plans as developed by Marshal Ferdinand Foch in 1919 were based on the assumption that in the event of a war with the Reich, the French forces in the Rhineland were to embark upon an offensive to seize the Ruhr.[18] A variant of the Foch plan had been used by Poincaré in 1923 when he ordered the French occupation of the Ruhr.[18]

French plans for an offensive in the 1920s were realistic, as Versailles had forbidden German conscription, and the Reichswehr was limited to 100,000 men. Once the French forces left the Rhineland in 1930, this form of leverage with the Rhineland as collateral was no longer available to Paris, which from then on had to depend on Berlin's word that it would continue to abide by the terms of the Versailles and Locarno treaties, which stated that the Rhineland was to stay demilitarised forever.[18] Given that Germany had engaged in covert rearmament with the co-operation of the Soviet Union starting in 1921 (a fact that had become public knowledge in 1926) and that every German government had gone out of its way to insist on the moral invalidity of Versailles, claiming it was based upon the so-called Kriegsschuldlüge ("War guilt lie") that Germany started the war in 1914, the French had little faith that the Germans would willingly allow the Rhineland's demilitarised status to continue forever, and believed that at some time in the future, Germany would rearm in violation of Versailles, reintroduce conscription and remilitarise the Rhineland.[18] The decision to build the Maginot Line in 1929 was a tacit French admission that without the Rhineland as collateral, Germany was soon going to rearm and that the terms of Part V had a limited lifespan.[18]

After 1918, the German economy was twice as large as that of France; Germany had a population of 70 million compared to France's 40 million, and the French economy was hobbled by the need to reconstruct the enormous damage of World War I, while German territory had seen little fighting. French military chiefs were dubious about their ability to win another war against Germany on its own, especially an offensive war.[18] French decision-makers knew that the victory of 1918 had been achieved because the British Empire and the United States were allies in the war and that the French would have been defeated on their own.[17] With the United States isolationist and Britain stoutly refusing to make the "continental commitment" to defend France on the same scale as in World War I, the prospects of Anglo-American assistance in another war with Germany appeared to be doubtful at best.[17] Versailles did not call for military sanctions in the event of the German military reoccupying the Rhineland or breaking Part V, while Locarno committed Britain and Italy to come to French aid in the event of a "flagrant violation" of the Rhineland's demilitarised status, it did not define what a "flagrant violation" would be.[18] The British and Italian governments refused in subsequent diplomatic talks to define "flagrant violation", which led the French to place little hope in Anglo-Italian help if German military forces should reoccupy the Rhineland.[18] Given the diplomatic situation in the late 1920s, the Quai d'Orsay informed the government that French military planning should be based on a worst-case scenario that France would fight the next war against Germany without the help of Britain or the United States.[18]

France had an alliance with Belgium and with the states of the Cordon sanitaire, as the French alliance system in Eastern Europe was known. Although the alliances with Belgium, Poland, Czechoslovakia, Romania and Yugoslavia were appreciated in Paris, it was widely understood that this was no compensation for the absence of Britain and the United States. The French military was especially insistent that the population disparity made an offensive war of manoeuvre and swift advances suicidal, as there would always be far more German divisions; a defensive strategy was needed to counter Germany.[18] The French assumption was always that Germany would not go to war without conscription, which would allow the German Army to take advantage of the Reich's numerical superiority. Without the natural defensive barrier provided by the Rhine River, French generals argued that France needed a new defensive barrier made of concrete and steel to replace it.[18] The power of properly dug-in defensive trenches had been amply demonstrated during World War I, when a few soldiers manning a single machine gun post could kill hundreds of the enemy in the open and therefore building a massive defensive line with subterranean concrete shelters was the most rational use of French manpower.[19]

The American historian William Keylor wrote that given the diplomatic conditions of 1929 and likely trends – with the United States isolationist and Britain unwilling to make the "continental commitment" – the decision to build the Maginot Line was not irrational and stupid, as building the Maginot Line was a sensible response to the problems that would be created by the coming French withdrawal from the Rhineland in 1930.[19] Part of the rationale for the Maginot Line stemmed from the severe French losses during the First World War and their effect on the French population.[20] The drop in the birth rate during and after the war, resulting in a national shortage of young men, created an "echo" effect on the generation that provided the French conscript army in the mid-1930s.[20] Faced with a manpower shortage, French planners had to rely more on older and less fit reservists, who would take longer to mobilise and would diminish the French industry because they would leave their jobs. Static defensive positions were therefore intended not only to buy time but to economise on men by defending an area with fewer and less mobile forces. However, in 1940, France deployed about twice as many men, 36 divisions (roughly one third of its force), for the defence of the Maginot Line in Alsace and Lorraine. In contrast, the opposing German Army Group C only contained 19 divisions, fewer than a seventh of the force committed in the Manstein Plan for the invasion of France.[21] Reflecting memories of World War I, the French General Staff had developed the concept of la puissance du feu ("the power of fire"), the power of artillery dug in and sheltered by concrete and steel, to inflict devastating losses on an attacking force.[22]

The principal fortified section of the Maginot Line

French planning for war with Germany was always based on the assumption that the war would be la guerre de longue durée (the long war), in which the superior economic resources of the Allies would gradually grind the Germans down.[23] The fact that the Wehrmacht embraced the strategy of Blitzkrieg (Lightning War) with the vision of swift wars in which Germany would win quickly via a knockout blow was a testament to the fundamental soundness of the concept of la guerre de longue durée.[23] Germany had the largest economy in Europe but lacked many of the raw materials necessary for a modern industrial economy (making the Reich vulnerable to a blockade) and the ability to feed its population. The guerre de longue durée strategy called for the French to halt the expected German offensive meant to give the Reich a swift victory; afterwards, there would be an attrition struggle; once the Germans were exhausted, France would begin an offensive to win the war.[23]

The Maginot Line was intended to block the main German blow if it should come via eastern France and divert it through Belgium, where French forces would meet and stop the Germans.[24] The Germans were expected to fight costly offensives, whose failures would sap the strength of the Reich, while the French waged a total war, mobilising the resources of France, its empire and allies.[25] Besides the demographic reasons, a defensive strategy served the needs of French diplomacy towards Great Britain.[26] The French imported a third of their coal from Britain, and 32 per cent of all imports through French ports were carried by British ships.[26] Of French trade, 35 per cent was with the British Empire and the majority of the tin, rubber, jute, wool and manganese used by France came from the British Empire.[26]

About 55 per cent of overseas imports arrived in France via the Channel ports of Calais, Le Havre, Cherbourg, Boulogne, Dieppe, Saint-Malo and Dunkirk.[26] Germany had to import most of its iron, rubber, oil, bauxite, copper and nickel, making naval blockade a devastating weapon against the German economy.[27] For economic reasons, the success of the strategy of la guerre de longue durée would at the very least require Britain to maintain a benevolent neutrality, preferably to enter the war as an ally as British sea power could protect French imports while depriving Germany of hers. A defensive strategy based on the Maginot Line was an excellent way of demonstrating to Britain that France was not an aggressive power and would only go to war in the event of German aggression, a situation that would make it more likely that Britain would enter the war on France's side.[28]

The line was built in several phases from 1930 by the Service Technique du Génie (STG), overseen by Commission d'Organisation des Régions Fortifiées (CORF). The main construction was largely completed by 1939, at the cost of around 3 billion French francs (around 3.9 billion in today's U.S. dollar’s worth). The line stretched from Switzerland to Luxembourg and a much lighter extension was extended to the Strait of Dover after 1934. The original construction did not cover the area ultimately chosen by the Germans for their first challenge, which was through the Ardennes in 1940, a plan known as Fall Gelb (Case Yellow), due to the neutrality of Belgium. The location of this attack, chosen because of the location of the Maginot Line, was through the Belgian Ardennes Forest (sector 4), which is off the map to the left of Maginot Line sector 6 (as marked).

81 mm (3.2 in) mortar

The specification of the defences was very high, with extensive and interconnected bunker complexes for thousands of men; there were 45 main forts (grands ouvrages) at intervals of 15 km (9.3 mi), 97 smaller forts (petits ouvrages) and 352 casemates between, with over 100 km (62 mi) of tunnels. Artillery was coordinated with protective measures to ensure that one fort could support the next in line by bombarding it directly without harm. The largest guns were, therefore 135 mm (5.3 in) fortress guns; larger weapons were to be part of the mobile forces and were to be deployed behind the lines.

The fortifications did not extend through the Ardennes Forest (which was believed to be impenetrable by Commander-in-Chief Maurice Gamelin) or along France's border with Belgium because the two countries had signed an alliance in 1920, by which the French army would operate in Belgium if the German forces invaded. However, after France had failed to counter the German remilitarisation of the Rhineland, Belgium—thinking that France was not a reliable ally—abrogated the treaty in 1936 and declared neutrality. France quickly extended the Maginot Line along the Franco-Belgian border, but not to the standard of the rest of the line. As the water table in this region is high, there was the danger of underground passages getting flooded, which the line designers knew would be difficult and expensive to overcome.

In 1939 U.S. Army officer Kenneth Nichols visited the Metz sector, where he was impressed by the formidable formations which he thought the Germans would have to outflank by driving through Belgium. In discussion with General Brousseau, the commander of the Metz sector and other officers, the general outlined the French problem in extending the line to the sea in that placing the line along the Belgian-German border required the agreement of Belgium, but putting the line along the French-Belgian border relinquished Belgium to the Germans. Another complication was Holland, and the various governments never resolved their problems.[29]

Corridor inside the Fort Saint-Gobain near Modane in the Alps. The Decauville

When the British Expeditionary Force landed in France in September 1939, they and the French reinforced and extended the Maginot line to the sea in a flurry of construction from 1939 to 1940, accompanied by general improvements all along the line. The final line was strongest around the industrial regions of Metz, Lauter and Alsace, while other areas were, in comparison, only weakly guarded. In contrast, the propaganda about the line made it appear far greater a construction than it was; illustrations showed multiple storeys of interwoven passages and even underground rail yards and cinemas. This reassured allied civilians.

Czechoslovakia also feared Hitler and began building its own defences. As an ally of France, they got advice on the Maginot design and applied it to Czechoslovak border fortifications. The design of the casemates is similar to the ones found in the southern part of the Maginot Line, and photographs of them are often confused with Maginot forts. Following the Munich Agreement and the German occupation of Czechoslovakia, the Germans were able to use the Czech fortifications to plan attacks that proved successful against the western fortifications (the Belgian Fort Eben-Emael is the best-known example).

Combat block 1 at the fortress Limeiln (ouvrage Four-à-Chaux, Alsace), showing signs of German testing of explosives inside some fortresses between 1942 and 1944

The World War II German invasion plan of 1940 (Sichelschnitt) was designed to deal with the line. A decoy force sat opposite the line while a second Army Group cut through the Low Countries of Belgium and the Netherlands, as well as through the Ardennes Forest, which lay north of the main French defences. Thus the Germans were able to avoid a direct assault on the Maginot Line by violating the neutrality of Belgium, Luxembourg and the Netherlands. Attacking on 10 May, German forces were well into France within five days and they continued to advance until 24 May, when they stopped near Dunkirk.

During the advance to the English Channel, the Germans overran France's border defence with Belgium and several Maginot Forts in the Maubeuge area whilst the Luftwaffe simply flew over it. On 19 May, the German 16th Army captured the isolated petit ouvrage La Ferté (south-east of Sedan) after conducting a deliberate assault by combat engineers backed up by heavy artillery, taking the fortifications in only four days.[30] The entire French crew of 107 soldiers was killed during the action. On 14 June 1940, the day Paris fell, the German 1st Army went over to the offensive in "Operation Tiger" and attacked the Maginot Line between St Avold and Saarbrücken. The Germans then broke through the fortification line as defending French forces retreated southward. In the following days, infantry divisions of the 1st Army attacked fortifications on each side of the penetration, capturing four petits ouvrages. The 1st Army also conducted two attacks against the Maginot Line further to the east in northern Alsace. One attack broke through a weak section of the line in the Vosges Mountains, but the French defenders stopped a second attack near Wissembourg. On 15 June, infantry divisions of the German 7th Army attacked across the Rhine River in Operation "Small Bear", penetrating the defences deep and capturing the cities of Colmar and Strasbourg.

By early June, the German forces had cut off the line from the rest of France, and the French government was making overtures for an armistice, which was signed on 22 June in Compiègne. As the line was surrounded, the German Army attacked a few ouvrages from the rear but was unsuccessful in capturing any significant fortifications. The main fortifications of the line were still mostly intact, many commanders were prepared to hold out, and the Italian advance had been contained. Nevertheless, Maxime Weygand signed the surrender instrument and the army was ordered out of their fortifications to be taken to POW camps.

When the Allied forces invaded in June 1944, the line, now held by German defenders, was again largely bypassed; fighting touched only portions of the fortifications near Metz and in northern Alsace towards the end of 1944. During the German offensive Operation Nordwind in January 1945, Maginot Line casemates and fortifications were utilised by Allied forces, especially in the Bas-Rhin department in Grand Est, and some German units had been supplemented with flamethrower tanks in anticipation of this possibility.[31] Stephen Ambrose wrote that in January 1945, "a part of the line was used for the purpose it had been designed for and showed what a superb fortification it was." Here the Line ran east-west, around the villages of Rittershoffen and Hatten, south of Wissembourg.[32]

The view from a battery at Ouvrage Schoenenbourg in Alsace. A retractable turret is in the left foreground.

After the war, the French re-manned the line and underwent some modifications. With the advent of French nuclear weapons in the early 1960s, the line became an expensive anachronism. Some of the larger ouvrages were converted to command centres. When France withdrew from NATO's military component in 1966, much of the line was abandoned, with the NATO facilities turned back over to French forces and the rest of it auctioned off to the public or left to decay.[33] A number of old fortifications have now been turned into wine cellars, a mushroom farm, and even a disco. Besides that, a few private houses are built atop some blockhouses.[34]

View of the village of Lembach in Alsace (north-east), taken from combat unit number 5 of the fortress ouvrage Four-à-Chaux

Ouvrage Rochonvillers was retained by the French Army as a command centre into the 1990s but was deactivated following the disappearance of the Soviet threat. Ouvrage Hochwald is the only facility in the main line that remains in active service as a hardened command facility for the French Air Force known as Drachenbronn Airbase.

In 1968, when scouting locations for On Her Majesty's Secret Service, producer Harry Saltzman used his French contacts to gain permission to use portions of the Maginot Line as SPECTRE headquarters in the film. Saltzman provided art director Syd Cain with a tour of the complex. Still, Cain said that the location would be challenging to light and film inside and that artificial sets could be constructed at the studios for a fraction of the cost.[35] The idea was shelved.