The Alpine Wall ( Vallo Alpino ) was an Italian system of fortifications along the 1,851 km (1,150 mi) of Italy 's northern frontier. Built in the years leading up to World War II at the direction of Italian dictator Benito Mussolini , the defensive line faced France , Switzerland , Austria , and Yugoslavia . It was defended by the " Guardia alla Frontiera " (GaF), Italian special troops.
156-608: The Alpine line was similar in concept to other fortifications of the same era, including the Maginot Line of France, the Siegfried Line of Germany, and the National Redoubt of Switzerland . Italy's land frontiers were in most places mountainous and easily defended, but in the years leading up to World War II, Italy's relations with its neighbours were uneasy. Even in its dealings with its German ally, Italy
312-484: A principal line of resistance made up of the most heavily armed ouvrages , which can be roughly translated as fortresses or big defensive works. This consisted of blockhouses and strong-houses, which were often camouflaged as residential homes, built within a few metres of the border and manned by troops to give the alarm in the event of a surprise attack and to delay enemy tanks with prepared explosives and barricades . Approximately 5 km (3 mi) behind
468-535: A tunnel network with attached underground facilities, such as barracks, electric generators , ventilation systems, mess halls , infirmaries and supply caches. Their crew consisted of between 100 and 200 men. These fortresses were the most important fortifications on the Maginot Line, having the sturdiest construction and the heaviest artillery. These were composed of at least six "forward bunker systems" or "combat blocks" and two entrances and were connected via
624-641: A "tiny wedge" into the Line. 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 . Camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include
780-436: A background that is brighter than an animal's body or military vehicle; it is a form of active camouflage. It is notably used by some species of squid , such as the firefly squid and the midwater squid . The latter has light-producing organs ( photophores ) scattered all over its underside; these create a sparkling glow that prevents the animal from appearing as a dark shape when seen from below. Counterillumination camouflage
936-429: A clear evolutionary advantage in plants: they would tend to escape from being eaten by herbivores . Another possibility is that some plants have leaves differently coloured on upper and lower surfaces or on parts such as veins and stalks to make green-camouflaged insects conspicuous, and thus benefit the plants by favouring the removal of herbivores by carnivores. These hypotheses are testable. Some animals, such as
1092-403: A combination of the two. Most forms of camouflage are ineffective when the camouflaged animal or object moves, because the motion is easily seen by the observing predator, prey or enemy. However, insects such as hoverflies and dragonflies use motion camouflage : the hoverflies to approach possible mates, and the dragonflies to approach rivals when defending territories. Motion camouflage
1248-687: A defensive strategy was needed to counter Germany. 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. The power of properly dug-in defensive trenches had been amply demonstrated during World War I, when
1404-463: A depth of 2 m (6 ft 7 in). These anti-tank obstacles extended from end to end in front of the main works, over hundreds of kilometres, interrupted only by extremely dense forests, rivers, or other nearly impassable terrains. The anti-tank obstacle system was followed by an anti-personnel obstacle system made primarily of dense barbed wire. Anti-tank road barriers also made it possible to block roads at necessary points of passage through
1560-466: 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. 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
1716-442: A fish can be seen by a factor of 6 compared to a fish with a nominal 2% reflectance. Species with this adaptation are widely dispersed in various orders of the phylogenetic tree of bony fishes ( Actinopterygii ), implying that natural selection has driven the convergent evolution of ultra-blackness camouflage independently many times. In mimesis (also called masquerade ), the camouflaged object looks like something else which
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#17327839738731872-466: A good view of the surrounding area. Their purpose was to locate the enemy, direct and correct the indirect fire of artillery, and report on the progress and position of critical enemy units. These are large reinforced buried concrete bunkers, equipped with armoured turrets containing high-precision optics, connected with the other fortifications by field telephone and wireless transmitters (known in French by
2028-475: A high contrast pattern that could be disruptive coloration, the adults are very conspicuous when in the open. Some authors have argued that adult giraffes are cryptic, since when standing among trees and bushes they are hard to see at even a few metres' distance. However, adult giraffes move about to gain the best view of an approaching predator, relying on their size and ability to defend themselves, even from lions, rather than on camouflage. A different explanation
2184-519: A mirror oriented vertically makes animals such as fish invisible from the side. Most fish in the upper ocean such as sardine and herring are camouflaged by silvering. The marine hatchetfish is extremely flattened laterally, leaving the body just millimetres thick, and the body is so silvery as to resemble aluminium foil . The mirrors consist of microscopic structures similar to those used to provide structural coloration : stacks of between 5 and 10 crystals of guanine spaced about 1 ⁄ 4 of
2340-606: A mixture of new weaponry and older equipment from World War I . Provisions were made to deal with the use of poison gas. Much of the armour was obtained from Germany in compensation for Italian military ventures on behalf of the Axis . Little use was made of the Alpine Wall during World War II . During the Italian invasion of France in 1940, some western forts such as Fort Chaberton exchanged fire with their French counterparts of
2496-681: 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
2652-438: A network of tunnels that often had narrow gauge electric railways for transport between bunker systems. The blocks contained infrastructure such as power stations, independent ventilating systems, barracks and mess halls, kitchens, water storage and distribution systems, hoists, ammunition stores, workshops and spare parts and food stores. Their crews ranged from 500 to more than 1,000 men. These were located on hills that provided
2808-404: A particularly black skin which reflected only 0.044% of 480 nm wavelength light. The ultra-blackness is achieved with a thin but continuous layer of particles in the dermis , melanosomes . These particles both absorb most of the light, and are sized and shaped so as to scatter rather than reflect most of the rest. Modelling suggests that this camouflage should reduce the distance at which such
2964-411: A period of about 8000 years the single agouti gene developed 9 mutations that each made expression of yellow fur stronger under natural selection, and largely eliminated melanin-coding black fur coloration. On the other hand, all black domesticated cats have deletions of the agouti gene that prevent its expression, meaning no yellow or red color is produced. The evolution, history and widespread scope of
3120-502: A predator blends in with the background, enabling it to approach prey). His experiments showed that swallow-tailed moth pupae were camouflaged to match the backgrounds on which they were reared as larvae . Poulton's "general protective resemblance" was at that time considered to be the main method of camouflage, as when Frank Evers Beddard wrote in 1892 that "tree-frequenting animals are often green in colour. Among vertebrates numerous species of parrots , iguanas , tree-frogs , and
3276-409: A reason, such as to lure prey. For example, the nematocysts (stinging cells) of the transparent siphonophore Agalma okenii resemble small copepods . Examples of transparent marine animals include a wide variety of larvae , including radiata (coelenterates), siphonophores, salps (floating tunicates ), gastropod molluscs , polychaete worms, many shrimplike crustaceans , and fish; whereas
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#17327839738733432-693: A reproductive advantage, enabling them to leave more offspring, on average, than other members of the same species . In his Origin of Species , Darwin wrote: When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather , and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey ; and hawks are guided by eyesight to their prey, so much so, that on parts of
3588-622: A slow rate that would allow the French time to bring up reserves and counterattacks. The German Army, having reformulated their plans from a repeat of the First World War-era plan, became aware of and exploited this weak point in the French defensive front. A rapid advance through the forest and across the River Meuse encircled much of the Allied forces, resulting in a sizeable force having to be evacuated at Dunkirk and leaving
3744-505: A small elastic sac, which can be stretched or allowed to relax under the control of the brain to vary its opacity. By controlling chromatophores of different colours, cephalopods can rapidly change their skin patterns and colours. On a longer timescale, animals like the Arctic hare , Arctic fox , stoat , and rock ptarmigan have snow camouflage , changing their coat colour (by moulting and growing new fur or feathers) from brown or grey in
3900-416: A species of nudibranch that feeds on stony coral , utilizes specific cryptic patterning in reef ecosystems. The nudibranch syphons pigments from the consumed coral into the epidermis, adopting the same shade as the consumed coral. This allows the nudibranch to change colour (mostly between black and orange) depending on the coral system that it inhabits. However, P. melanocrachia can only feed and lay eggs on
4056-409: A wavelength apart to interfere constructively and achieve nearly 100 per cent reflection. In the deep waters that the hatchetfish lives in, only blue light with a wavelength of 500 nanometres percolates down and needs to be reflected, so mirrors 125 nanometres apart provide good camouflage. In fish such as the herring which live in shallower water, the mirrors must reflect a mixture of wavelengths, and
4212-452: Is acellular and highly transparent. This conveniently makes them buoyant , but it also makes them large for their muscle mass, so they cannot swim fast, making this form of camouflage a costly trade-off with mobility. Gelatinous planktonic animals are between 50 and 90 percent transparent. A transparency of 50 percent is enough to make an animal invisible to a predator such as cod at a depth of 650 metres (2,130 ft); better transparency
4368-475: Is achieved by moving so as to stay on a straight line between the target and a fixed point in the landscape; the pursuer thus appears not to move, but only to loom larger in the target's field of vision. Some insects sway while moving to appear to be blown back and forth by the breeze. The same method can be used for military purposes, for example by missiles to minimise their risk of detection by an enemy. However, missile engineers, and animals such as bats, use
4524-433: Is an important component of camouflage in all environments. For instance, tree-dwelling parakeets are mainly green; woodcocks of the forest floor are brown and speckled; reedbed bitterns are streaked brown and buff; in each case the animal's coloration matches the hues of its habitat. Similarly, desert animals are almost all desert coloured in tones of sand, buff, ochre, and brownish grey, whether they are mammals like
4680-436: Is argued that these juvenile giraffes must be very well camouflaged; this is supported by coat markings being strongly inherited . The possibility of camouflage in plants was little studied until the late 20th century. Leaf variegation with white spots may serve as camouflage in forest understory plants, where there is a dappled background; leaf mottling is correlated with closed habitats. Disruptive camouflage would have
4836-418: Is common in military usage, both for uniforms and for military vehicles. Disruptive patterning, however, does not always achieve crypsis on its own, as an animal or a military target may be given away by factors like shape, shine, and shadow. The presence of bold skin markings does not in itself prove that an animal relies on camouflage, as that depends on its behaviour. For example, although giraffes have
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4992-435: Is fossil evidence of camouflaged insects going back over 100 million years, for example lacewings larvae that stick debris all over their bodies much as their modern descendants do, hiding them from their prey. Dinosaurs appear to have been camouflaged, as a 120 million year old fossil of a Psittacosaurus has been preserved with countershading . Camouflage does not have a single genetic origin. However, studying
5148-403: Is implied by young giraffes being far more vulnerable to predation than adults. More than half of all giraffe calves die within a year, and giraffe mothers hide their newly born calves, which spend much of the time lying down in cover while their mothers are away feeding. The mothers return once a day to feed their calves with milk. Since the presence of a mother nearby does not affect survival, it
5304-525: Is less often used for military camouflage, despite Second World War experiments that showed its effectiveness. English zoologist Hugh Cott encouraged the use of methods including countershading, but despite his authority on the subject, failed to persuade the British authorities. Soldiers often wrongly viewed camouflage netting as a kind of invisibility cloak, and they had to be taught to look at camouflage practically, from an enemy observer's viewpoint. At
5460-434: Is mediated by a type of chromatophore known as melanophores that contain dark pigment. A melanophore is star-shaped; it contains many small pigmented organelles which can be dispersed throughout the cell, or aggregated near its centre. When the pigmented organelles are dispersed, the cell makes a patch of the animal's skin appear dark; when they are aggregated, most of the cell, and the animal's skin, appears light. In frogs,
5616-540: Is not every reason to believe it the very best conceivable device for the concealment of its wearer", and using paintings such as Peacock in the Woods (1907) to reinforce his argument. Thayer was roundly mocked for these views by critics including Teddy Roosevelt . The English zoologist Hugh Cott 's 1940 book Adaptive Coloration in Animals corrected Thayer's errors, sometimes sharply: "Thus we find Thayer straining
5772-404: Is off the map to the left of Maginot Line sector 6 (as marked). 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
5928-739: Is possible that some plants use camouflage to evade being eaten by herbivores . Military camouflage was spurred by the increasing range and accuracy of firearms in the 19th century. In particular the replacement of the inaccurate musket with the rifle made personal concealment in battle a survival skill. In the 20th century, military camouflage developed rapidly, especially during the First World War . On land, artists such as André Mare designed camouflage schemes and observation posts disguised as trees. At sea , merchant ships and troop carriers were painted in dazzle patterns that were highly visible, but designed to confuse enemy submarines as to
6084-463: Is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 percent transparent in optimal lighting in shallow water. Therefore, sufficient transparency for camouflage is more easily achieved in deeper waters. Some tissues such as muscles can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to
6240-483: Is the likely function of the bioluminescence of many marine organisms, though light is also produced to attract or to detect prey and for signalling. Counterillumination has rarely been used for military purposes. " Diffused lighting camouflage " was trialled by Canada's National Research Council during the Second World War. It involved projecting light on to the sides of ships to match the faint glow of
6396-428: Is their mutual resemblance." He also explained the coloration of sea fish such as the mackerel : "Among pelagic fish it is common to find the upper surface dark-coloured and the lower surface white, so that the animal is inconspicuous when seen either from above or below." The artist Abbott Handerson Thayer formulated what is sometimes called Thayer's Law, the principle of countershading . However, he overstated
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6552-474: Is thought to have originated through transposition from symbiotic Aliivibrio fischeri bacteria, which provide bioluminescence to its hosts. While not all cephalopods use active camouflage , ancient cephalopods may have inherited the gene horizontally from symbiotic A. fischeri , with divergence occurred through subsequent gene duplication (such as in the case of Sepia officinalis ) or gene loss (as with cephalopods with no active camouflage capabilities). This
6708-640: Is unique as an instance of camouflage arising as an instance of horizontal gene transfer from an endosymbiont . However, other methods of horizontal gene transfer are common in the evolution of camouflage strategies in other lineages. Peppered moths and walking stick insects both have camouflage-related genes that stem from transposition events. The Agouti genes are orthologous genes involved in camouflage across many lineages. They produce yellow and red coloration ( phaeomelanin ), and work in competition with other genes that produce black (melanin) and brown (eumelanin) colours. In eastern deer mice , over
6864-696: The Alpine Line . Chaberton was hit by French 280mm field mortars and suffered disabling damage. In addition, some Alpine Wall fortifications were used defensively by Italian and German forces during the Second Battle of the Alps in 1944. At the end of the conflict, some of the western fortifications were destroyed. In the east former Austro-Hungarian territories that Italy acquired with the London treaty of 1915 were in 1947 awarded to Yugoslavia. Consequently,
7020-655: 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,
7176-568: The French Minister of War André Maginot , is a line of concrete fortifications , obstacles and weapon installations built by France in the 1930s to deter invasion by Nazi Germany and force them to move around the fortifications. It was impervious to most forms of attack; consequently, the Germans invaded through the Low Countries in 1940, passing it to the north. The line, which was supposed to be fully extended further towards
7332-652: The Natisone and Tagliamento rivers. The new line used tank turrets in a manner similar to German defences during the previous conflict, allowing 360-degree traverse and a high rate of fire. By 1976 this system was still considered useful in any type of conflict short of a nuclear war. The end of the Cold War brought an end to the usefulness of the Alpine Wall. The emplacements were partially stripped and sealed in 1991-1992. Only some active fortifications have been preserved. The fortifications were primarily constructed in
7488-538: The Soviet Union . The secret German-Soviet cooperation started in 1921. 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
7644-548: The gerbil or fennec fox , birds such as the desert lark or sandgrouse , or reptiles like the skink or horned viper . Military uniforms, too, generally resemble their backgrounds; for example khaki uniforms are a muddy or dusty colour, originally chosen for service in South Asia. Many moths show industrial melanism , including the peppered moth which has coloration that blends in with tree bark. The coloration of these insects evolved between 1860 and 1940 to match
7800-409: The green tree-snake are examples". Beddard did however briefly mention other methods, including the "alluring coloration" of the flower mantis and the possibility of a different mechanism in the orange tip butterfly . He wrote that "the scattered green spots upon the under surface of the wings might have been intended for a rough sketch of the small flowerets of the plant [an umbellifer ], so close
7956-401: The horned lizards of North America, have evolved elaborate measures to eliminate shadow . Their bodies are flattened, with the sides thinning to an edge; the animals habitually press their bodies to the ground; and their sides are fringed with white scales which effectively hide and disrupt any remaining areas of shadow there may be under the edge of the body. The theory that the body shape of
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#17327839738738112-442: The leopard 's spotted coat, the battledress of a modern soldier , and the leaf-mimic katydid 's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration , eliminating shadow, and countershading . In
8268-538: 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. 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. The drop in
8424-613: The British Empire. 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 . Germany had to import most of its iron, rubber, oil , bauxite , copper and nickel , making naval blockade a devastating weapon against the German economy . For economic reasons, the success of the strategy of la guerre de longue durée would at
8580-600: The British army having adopted "coats of motley hue and stripes of paint" for snipers. Cott takes the example of the larva of the blotched emerald moth, which fixes a screen of fragments of leaves to its specially hooked bristles, to argue that military camouflage uses the same method, pointing out that the "device is ... essentially the same as one widely practised during the Great War for the concealment, not of caterpillars, but of caterpillar-tractors, [gun] battery positions, observation posts and so forth." Movement catches
8736-663: The Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. The English zoologist Edward Bagnall Poulton studied animal coloration , especially camouflage. In his 1890 book The Colours of Animals , he classified different types such as "special protective resemblance" (where an animal looks like another object), or "general aggressive resemblance" (where
8892-730: 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
9048-522: The French could only go so far with alienating the British. 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 . In 1926, The Manchester Guardian ran an exposé showing the Reichswehr had been developing military technology forbidden by the Treaty of Versailles in
9204-537: The French occupation of the Ruhr. 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
9360-736: 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
9516-417: The Germans were exhausted, France would begin an offensive to win the war. 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. 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
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#17327839738739672-578: The Maginot Line. 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 line included the following retractable turrets. 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. The defences were first proposed by Marshal Joseph Joffre . He
9828-518: 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 . 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
9984-585: The Rhineland. 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. France had an alliance with Belgium and with the states of the Cordon sanitaire , as the French alliance system in Eastern Europe
10140-532: The Ruhr within a year. 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;
10296-529: The Treaty of Versailles, was abolished as a goodwill gesture reflecting the "Spirit of Locarno ". 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
10452-472: The acronym T.S.F., Télégraphie Sans Fil ). This system connected every fortification in the Maginot Line, including bunkers, infantry and artillery fortresses, observation posts and shelters. Two telephone wires were placed parallel to the line of fortifications, providing redundancy in case a wire was cut. There were places along the cable where dismounted soldiers could connect to the network. These were found from 500–1,000 m (1,600–3,300 ft) behind
10608-409: The adults of most of these are opaque and pigmented, resembling the seabed or shores where they live. Adult comb jellies and jellyfish obey the rule, often being mainly transparent. Cott suggests this follows the more general rule that animals resemble their background: in a transparent medium like seawater, that means being transparent. The small Amazon River fish Microphilypnus amazonicus and
10764-644: 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. The entire French crew of 107 soldiers
10920-483: The agouti gene shows that different organisms often rely on orthologous or even identical genes to develop a variety of camouflage strategies. While camouflage can increase an organism's fitness, it has genetic and energetic costs. There is a trade-off between detectability and mobility. Species camouflaged to fit a specific microhabitat are less likely to be detected when in that microhabitat, but must spend energy to reach, and sometimes to remain in, such areas. Outside
11076-662: 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. 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
11232-438: The body outline, making it harder to precisely identify and locate. However, disruptive patterns result in higher predation. Disruptive patterns that specifically involve visible symmetry (such as in some butterflies) reduce survivability and increase predation. Some researchers argue that because wing-shape and color pattern are genetically linked, it is genetically costly to develop asymmetric wing colorations that would enhance
11388-456: The body. On these, the nymph spreads an inner layer of fine particles and an outer layer of coarser particles. The camouflage may conceal the bug from both predators and prey. Similar principles can be applied for military purposes, for instance when a sniper wears a ghillie suit designed to be further camouflaged by decoration with materials such as tufts of grass from the sniper's immediate environment. Such suits were used as early as 1916,
11544-570: The border there was a line of anti-tank blockhouses that were intended to provide resistance to armoured assault, sufficient to delay the enemy and allow time for the crews of the C.O.R.F. ouvrages to be ready at their battle stations. These outposts covered the main passages within the principal line. This line began 10 km (6 mi) behind the border. It was preceded by anti-tank obstacles made of metal rails planted vertically in six rows, with heights varying from 0.70–1.40 metres (2 ft 4 in – 4 ft 7 in) and buried to
11700-442: The branches of host-coral, Platygyra carnosa , which limits the geographical range and efficacy in nudibranch nutritional crypsis. Furthermore, the nudibranch colour change is not immediate, and switching between coral hosts when in search for new food or shelter can be costly. The costs associated with distractive or disruptive crypsis are more complex than the costs associated with background matching. Disruptive patterns distort
11856-457: The camouflage consists of two surfaces, each with the simple function of providing concealment against a specific background, such as a bright water surface or the sky. The body of a shark or the fuselage of an aircraft is not gradated from light to dark to appear flat when seen from the side. The camouflage methods used are the matching of background colour and pattern, and disruption of outlines. Counter-illumination means producing light to match
12012-468: The case in the 1909 book Concealing-Coloration in the Animal Kingdom , arguing that "All patterns and colors whatsoever of all animals that ever preyed or are preyed on are under certain normal circumstances obliterative" (that is, cryptic camouflage), and that "Not one ' mimicry ' mark, not one ' warning color '... nor any ' sexually selected ' color, exists anywhere in the world where there
12168-676: 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). The World War II German invasion plan of 1940 ( Sichelschnitt )
12324-403: The change is controlled relatively slowly, mainly by hormones . In fish, the change is controlled by the brain, which sends signals directly to the chromatophores, as well as producing hormones. The skins of cephalopods such as the octopus contain complex units, each consisting of a chromatophore with surrounding muscle and nerve cells. The cephalopod chromatophore has all its pigment grains in
12480-411: The changing colour of the tree trunks on which they rest, from pale and mottled to almost black in polluted areas. This is taken by zoologists as evidence that camouflage is influenced by natural selection , as well as demonstrating that it changes where necessary to resemble the local background. Disruptive patterns use strongly contrasting, non-repeating markings such as spots or stripes to break up
12636-540: The colour-changing abilities, both for camouflage and for signalling , of cephalopods including the octopus, in his Historia animalium : The octopus ... seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also when alarmed . Camouflage has been a topic of interest and research in zoology for well over a century. According to Charles Darwin 's 1859 theory of natural selection , features such as camouflage evolved by providing individual animals with
12792-411: The combination of behaviours and other methods of crypsis involved, young giraffes seek cover, lie down, and keep still, often for hours until their mothers return; their skin pattern blends with the pattern of the vegetation, while the chosen cover and lying position together hide the animals' shadows. The flat-tail horned lizard similarly relies on a combination of methods: it is adapted to lie flat in
12948-588: 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. When
13104-500: The concept of la guerre de longue durée . 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
13260-489: 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
13416-504: The countershaded animal nearly invisible against a suitable background. Thayer observed that "Animals are painted by Nature, darkest on those parts which tend to be most lighted by the sky's light, and vice versa ". Accordingly, the principle of countershading is sometimes called Thayer's Law . Countershading is widely used by terrestrial animals , such as gazelles and grasshoppers; marine animals, such as sharks and dolphins ; and birds, such as snipe and dunlin . Countershading
13572-712: 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. 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. French planning for war with Germany
13728-492: The defences 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
13884-513: The east. Three zones were designated at increasing distances from the frontier: Three types of fortifications were provided: The work, which was carried out in secrecy using Italian labor, was a significant economic burden, resulting in 208 installations with 647 machine guns and fifty artillery pieces. Construction continued until 1942; a report by General Vittorio Ambrosio on 3 October 1942 recorded that 1,475 bunkers had been completed and 450 more were under construction. The forts were armed with
14040-502: The efficacy of disruptive cryptic patterning. Symmetry does not carry a high survival cost for butterflies and moths that their predators views from above on a homogeneous background, such as the bark of a tree. On the other hand, natural selection drives species with variable backgrounds and habitats to move symmetrical patterns away from the centre of the wing and body, disrupting their predators' symmetry recognition. Camouflage can be achieved by different methods, described below. Most of
14196-622: The entire eastern part of the pre-WW2 fortifications were thus on the Yugoslav side and are now on Slovenian territory. The 1947 Paris Peace Treaty forbade the construction or expansion of fortifications within twenty kilometers of the border. However, with Italy's membership in NATO , construction began on a new defensive line from Austria to the Adriatic along the Yugoslavian border along
14352-558: The event of an enemy offensive. These were built near the major fortifications so fortress ( ouvrage ) crews could reach their battle stations in the shortest possible time in the event of a surprise attack during peacetime. A network of 600 mm ( 1 ft 11 + 5 ⁄ 8 in ) narrow gauge railways was built to rearm and resupply the main fortresses ( ouvrages ) from supply depots up to 50 km (31 mi) away. Petrol-engined armoured locomotives pulled supply trains along these narrow-gauge lines. (A similar system
14508-555: 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. 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
14664-419: The eye of prey animals on the lookout for predators, and of predators hunting for prey. Most methods of crypsis therefore also require suitable cryptic behaviour, such as lying down and keeping still to avoid being detected, or in the case of stalking predators such as the tiger , moving with extreme stealth, both slowly and quietly, watching its prey for any sign they are aware of its presence. As an example of
14820-400: The features of their bodies, and to match their backgrounds. For example, a caddisfly larva builds a decorated case and lives almost entirely inside it; a decorator crab covers its back with seaweed, sponges, and stones. The nymph of the predatory masked bug uses its hind legs and a ' tarsal fan' to decorate its body with sand or dust. There are two layers of bristles ( trichomes ) over
14976-738: The fish accordingly has crystal stacks with a range of different spacings. A further complication for fish with bodies that are rounded in cross-section is that the mirrors would be ineffective if laid flat on the skin, as they would fail to reflect horizontally. The overall mirror effect is achieved with many small reflectors, all oriented vertically. Silvering is found in other marine animals as well as fish. The cephalopods , including squid, octopus and cuttlefish, have multilayer mirrors made of protein rather than guanine. Some deep sea fishes have very black skin, reflecting under 0.5% of ambient light. This can prevent detection by predators or prey fish which use bioluminescence for illumination. Oneirodes had
15132-494: The flanking heights of the valleys, with works within the valleys only where they were sufficiently wide. Anti-tank guns, artillery and machine guns were trained on prepared fields of fire, with observation stations at higher points. Shelters for infantry were located rearwards. A system of communications links and roads, or for higher locations, ropeways were provided for communication and supply. The individual fortifications were typically built in rock on valley sides. Where this
15288-539: 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. In January 1945 von Luck with 21 Panzerdivision
15444-516: The fortresses. They were also accommodated in complexes of wooden housing adjacent to each fortress, which were more comfortable than living inside, but were not expected to survive wartime bombardment. The training was carried out at a fortress near the town of Bitche in Moselle in Lorraine , built in a military training area and so capable of live fire exercises. This was impossible elsewhere as
15600-482: The genetic components and various ecological pressures that drive crypsis. Camouflage is a soft-tissue feature that is rarely preserved in the fossil record, but rare fossilised skin samples from the Cretaceous period show that some marine reptiles were countershaded. The skins, pigmented with dark-coloured eumelanin , reveal that both leatherback turtles and mosasaurs had dark backs and light bellies. There
15756-436: The genetic components of camouflage in specific organisms illuminates the various ways that crypsis can evolve among lineages. Many cephalopods have the ability to actively camouflage themselves, controlling crypsis through neural activity. For example, the genome of the common cuttlefish includes 16 copies of the reflectin gene, which grants the organism remarkable control over coloration and iridescence. The reflectin gene
15912-573: The geographical limits of the Maginot Line; when Germany invaded the Netherlands and Belgium , they carried out plans to form an aggressive front that cut across Belgium and connected to the Maginot Line. The French line was weak near the Ardennes . General Maurice Gamelin , when drafting the Dyle Plan , believed this region, with its rough terrain, would be an unlikely invasion route of German forces; if it were traversed, it would be done at
16068-594: The heavy guns, and the engineers were responsible for maintaining and operating other specialist equipment, including all communications systems. All these troops wore distinctive uniform insignia and considered themselves among the elite of the French Army. During peacetime, fortresses were only partly manned by full-time troops. They would be supplemented by reservists who lived in the local area and who could be quickly mobilised in an emergency. Full-time Maginot Line troops were accommodated in barracks built close to
16224-399: The horned lizards which live in open desert is adapted to minimise shadow is supported by the one species which lacks fringe scales, the roundtail horned lizard , which lives in rocky areas and resembles a rock. When this species is threatened, it makes itself look as much like a rock as possible by curving its back, emphasizing its three-dimensional shape. Some species of butterflies, such as
16380-475: The line did not extend to the English Channel . French strategy, therefore, envisioned a move into Belgium to counter a German assault. Based on France's experience with trench warfare during World War I , the massive Maginot Line was built in the run-up to World War II , after the Locarno Conference in 1925 gave rise to a fanciful and optimistic "Locarno spirit". French military experts believed
16536-470: 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
16692-431: The line would deter German aggression because it would slow an invasion force long enough for French forces to mobilise and counterattack. The Maginot Line was invulnerable to aerial bombings and tank fire; it used underground railways as a backup. It also had state-of-the-art living conditions for garrisoned troops, supplying air conditioning and eating areas for their comfort. French and British officers had anticipated
16848-423: The local environment. As there is a lack of evidence for camouflage in the fossil record, studying the evolution of camouflage strategies is very difficult. Furthermore, camouflage traits must be both adaptable (provide a fitness gain in a given environment) and heritable (in other words, the trait must undergo positive selection ). Thus, studying the evolution of camouflage strategies requires an understanding of
17004-534: The method mainly for its efficiency rather than camouflage. Animals such as chameleon , frog, flatfish such as the peacock flounder , squid, octopus and even the isopod idotea balthica actively change their skin patterns and colours using special chromatophore cells to resemble their current background, or, as in most chameleons, for signalling . However, Smith's dwarf chameleon does use active colour change for camouflage. Each chromatophore contains pigment of only one colour. In fish and frogs, colour change
17160-428: The methods help to hide against a background; but mimesis and motion dazzle protect without hiding. Methods may be applied on their own or in combination. Many mechanisms are visual, but some research has explored the use of techniques against olfactory (scent) and acoustic (sound) detection. Methods may also apply to military equipment. Some animals' colours and patterns match a particular natural background. This
17316-466: The microhabitat, the organism has a higher chance of detection. Generalized camouflage allows species to avoid predation over a wide range of habitat backgrounds, but is less effective. The development of generalized or specialized camouflage strategies is highly dependent on the biotic and abiotic composition of the surrounding environment. There are many examples of the tradeoffs between specific and general cryptic patterning. Phestilla melanocrachia ,
17472-538: The night sky, requiring awkward external platforms to support the lamps. The Canadian concept was refined in the American Yehudi lights project, and trialled in aircraft including B-24 Liberators and naval Avengers . The planes were fitted with forward-pointing lamps automatically adjusted to match the brightness of the night sky. This enabled them to approach much closer to a target – within 3,000 yards (2,700 m) – before being seen. Counterillumination
17628-514: The open desert, relying on stillness, its cryptic coloration, and concealment of its shadow to avoid being noticed by predators. In the ocean, the leafy sea dragon sways mimetically, like the seaweeds amongst which it rests, as if rippled by wind or water currents. Swaying is seen also in some insects, like Macleay's spectre stick insect, Extatosoma tiaratum . The behaviour may be motion crypsis, preventing detection, or motion masquerade, promoting misclassification (as something other than prey), or
17784-442: The open ocean, where there is no background, the principal methods of camouflage are transparencying, silveringing, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid . Some animals, such as chameleons and octopuses , are capable of actively changing their skin pattern and colors , whether for camouflage or for signalling. It
17940-563: The other parts of the line were located in civilian areas. Although the name "Maginot Line" suggests a relatively thin linear fortification, it was 20–25 kilometres (12–16 miles) deep from the German border to the rear area. It was composed of an intricate system of strong points, fortifications and military facilities such as border guard posts, communications centres, infantry shelters, barricades, artillery, machine-gun and anti-tank-gun emplacements, supply depots, infrastructure facilities and observation posts. These various structures reinforced
18096-408: The outlines of an animal or military vehicle, or to conceal telltale features, especially by masking the eyes , as in the common frog . Disruptive patterns may use more than one method to defeat visual systems such as edge detection . Predators like the leopard use disruptive camouflage to help them approach prey, while potential prey use it to avoid detection by predators. Disruptive patterning
18252-618: 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", deeply penetrating
18408-514: The principal line of resistance. These were buried concrete bunkers designed to house and shelter up to a company of infantry (200 to 250 men). They had amenities such as electric generators, ventilation systems, water supplies, kitchens and heating, which allowed their occupants to hold out in the event of an attack. They could also be used as a local headquarters and counterattack base. Flood zones were natural basins or rivers that could be flooded on demand and thus constitute an additional obstacle in
18564-432: 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
18720-524: The resources of France, its empire and allies. Besides the demographic reasons, a defensive strategy served the needs of French diplomacy towards Great Britain. 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. 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
18876-585: The rest of the structure by gas-tight doorways. Units built after 1939 were designed to operate independently, cut off from utilities and supplies. Fortifications were camouflaged so that they appeared to blend with the surroundings, whether doors or embrasures were open or closed. Emergency escape routes were also provided. Armament typically included an anti-tank gun and a number of machine guns. Post-war units used tank turrets. Usual armament included: Fortifications were usually surrounded by minefields and barbed wire . Where feasible, an anti-tank ditch
19032-474: The same time in Australia , zoologist William John Dakin advised soldiers to copy animals' methods, using their instincts for wartime camouflage. The term countershading has a second meaning unrelated to "Thayer's Law". It is that the upper and undersides of animals such as sharks, and of some military aircraft, are different colours to match the different backgrounds when seen from above or from below. Here
19188-467: The shrimps it associates with, Pseudopalaemon gouldingi , are so transparent as to be "almost invisible"; further, these species appear to select whether to be transparent or more conventionally mottled (disruptively patterned) according to the local background in the environment. Where transparency cannot be achieved, it can be imitated effectively by silvering to make an animal's body highly reflective. At medium depths at sea, light comes from above, so
19344-477: The sides of a tank. The Peltier plate panels are heated and cooled to match either the vehicle's surroundings (crypsis), or an object such as a car (mimesis), when viewed in infrared. Countershading uses graded colour to counteract the effect of self-shadowing, creating an illusion of flatness. Self-shadowing makes an animal appear darker below than on top, grading from light to dark; countershading 'paints in' tones which are darkest on top, lightest below, making
19500-412: 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. The decision to build the Maginot Line in 1929
19656-462: The speckled wood, Pararge aegeria , minimise their shadows when perched by closing the wings over their backs, aligning their bodies with the sun, and tilting to one side towards the sun, so that the shadow becomes a thin inconspicuous line rather than a broad patch. Similarly, some ground-nesting birds, including the European nightjar , select a resting position facing the sun. Eliminating shadow
19812-465: 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,
19968-722: The summer to white in the winter; the Arctic fox is the only species in the dog family to do so. However, Arctic hares which live in the far north of Canada , where summer is very short, remain white year-round. The principle of varying coloration either rapidly or with the changing seasons has military applications. Active camouflage could in theory make use of both dynamic colour change and counterillumination. Simple methods such as changing uniforms and repainting vehicles for winter have been in use since World War II. In 2011, BAE Systems announced their Adaptiv infrared camouflage technology. It uses about 1,000 hexagonal panels to cover
20124-464: The tank obstacles. These bunkers were armed with twin machine-guns (abbreviated as JM — Jumelage de mitrailleuses — in French) and anti-tank guns of 37 or 47 mm (1.5 or 1.9 in). They could be single (with a firing room in one direction) or double (two firing rooms in opposite directions). These generally had two floors, with a firing level and a support/infrastructure level that provided
20280-835: The target's speed, range, and heading. During and after the Second World War , a variety of camouflage schemes were used for aircraft and for ground vehicles in different theatres of war. The use of radar since the mid-20th century has largely made camouflage for fixed-wing military aircraft obsolete. Non-military use of camouflage includes making cell telephone towers less obtrusive and helping hunters to approach wary game animals. Patterns derived from military camouflage are frequently used in fashion clothing, exploiting their strong designs and sometimes their symbolism. Camouflage themes recur in modern art, and both figuratively and literally in science fiction and works of literature. In ancient Greece, Aristotle (384–322 BC) commented on
20436-533: The terms of the Versailles and Locarno treaties, which stated that the Rhineland was to stay demilitarised forever. 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
20592-470: The theory to a fantastic extreme in an endeavour to make it cover almost every type of coloration in the animal kingdom." Cott built on Thayer's discoveries, developing a comprehensive view of camouflage based on "maximum disruptive contrast", countershading and hundreds of examples. The book explained how disruptive camouflage worked, using streaks of boldly contrasting colour, paradoxically making objects less visible by breaking up their outlines. While Cott
20748-420: The troops to the south unable to mount an effective resistance to the German invasion of France . The Maginot Line was built to fulfill several purposes: Maginot Line fortifications were manned by specialist units of fortress infantry, artillery and engineers. The infantry manned the lighter weapons of the fortresses and formed units with the mission of operating outside if necessary. Artillery troops operated
20904-484: The troops with rest and services ( power-generating units , reserves of water, fuel, food, ventilation equipment, etc.). The infantry casemates often had one or two "cloches" or turrets located on top of them. These GFM cloches were sometimes used to emplace machine guns or observation periscopes. 20 to 30 men manned them. These small fortresses reinforced the line of infantry bunkers . The petits ouvrages were generally made up of several infantry bunkers, connected by
21060-534: 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
21216-455: 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
21372-537: 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. 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. Versailles did not call for military sanctions in
21528-471: The war on France's side. 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
21684-508: The wavelength of visible light. A familiar example is the transparency of the lens of the vertebrate eye , which is made of the protein crystallin , and the vertebrate cornea which is made of the protein collagen . Other structures cannot be made transparent, notably the retinas or equivalent light-absorbing structures of eyes – they must absorb light to be able to function. The camera -type eye of vertebrates and cephalopods must be completely opaque. Finally, some structures are visible for
21840-401: The west to avoid such an occurrence, was finally scaled back in response to demands from Belgium . Indeed, Belgium feared it would be sacrificed in the event of another German invasion. The line has since become a metaphor for expensive efforts that offer a false sense of security. Constructed on the French side of its borders with Italy , Switzerland , Germany , Luxembourg and Belgium ,
21996-614: 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. 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. French decision-makers knew that
22152-524: 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. 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
22308-572: Was concerned about German ambitions towards the province of South Tyrol , inhabited by a German majority. Due to the rugged nature of the Alpine frontier, defences were confined to passes and observation posts in accessible locations. Work on the Alpine Wall began in 1931, intended to cover an arc from the Mediterranean coast at Ventimiglia in the west to Fiume on the Adriatic coast in
22464-558: 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
22620-682: 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
22776-497: Was developed with armoured steam engines in 1914–1918.) Initially above-ground but then buried, and connected to the civil power grid, these provided electric power to the many fortifications and fortresses. This was hauled by locomotives to planned locations to support the emplaced artillery in the fortresses, which was intentionally limited in range to 10–12 km (6–7 mi). There are 142 ouvrages , 352 casemates , 78 shelters, 17 observatories and around 5,000 blockhouses in
22932-682: Was identified as a principle of military camouflage during the Second World War . Many prey animals have conspicuous high-contrast markings which paradoxically attract the predator's gaze. These distractive markings may serve as camouflage by distracting the predator's attention from recognising the prey as a whole, for example by keeping the predator from identifying the prey's outline. Experimentally, search times for blue tits increased when artificial prey had distractive markings. Some animals actively seek to hide by decorating themselves with materials such as twigs, sand, or pieces of shell from their environment, to break up their outlines, to conceal
23088-404: 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
23244-425: 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;
23400-464: Was made obsolete by radar , and neither diffused lighting camouflage nor Yehudi lights entered active service. Many marine animals that float near the surface are highly transparent , giving them almost perfect camouflage. However, transparency is difficult for bodies made of materials that have different refractive indices from seawater. Some marine animals such as jellyfish have gelatinous bodies, composed mainly of water; their thick mesogloea
23556-498: Was more systematic and balanced in his view than Thayer, and did include some experimental evidence on the effectiveness of camouflage, his 500-page textbook was, like Thayer's, mainly a natural history narrative which illustrated theories with examples. Experimental evidence that camouflage helps prey avoid being detected by predators was first provided in 2016, when ground-nesting birds ( plovers and coursers ) were shown to survive according to how well their egg contrast matched
23712-406: Was not suitable, concrete was used for protection, with a minimum of openings and three to five metres of concrete thickness. Combat blocks were to the front, with ammunition rooms behind. Underground galleries connected the combat blocks and their support areas, such as the utility rooms, barracks, storage and command centres, with the main entry farthest to the rear. Combat areas were isolated from
23868-517: 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 ,
24024-480: Was powerful enough to deter successive German governments all through the 1920s from attempting any overt violation of Part V. 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. A variant of the Foch plan had been used by Poincaré in 1923 when he ordered
24180-636: Was provided. The Vallo Alpino was mainly defended by the 21,000 strong " Guardia alla Frontiera " (G.A.F.), a special Italian corps created in 1937. They defended the 1,851 km (1,150 mi) of northern Italian frontiers with the so-called "Vallo Alpino Occidentale" (487 km (303 mi) with France ), "Vallo Alpino Settentrionale" (724 km (450 mi) with Switzerland and 420 km (260 mi) with Austria ) and "Vallo Alpino Orientale" (220 km (140 mi) with Yugoslavia ). Maginot Line The Maginot Line ( French : Ligne Maginot , [lˈiɲ maʒinˈo] ), named after
24336-443: Was tasked with cutting through the old Maginot Line defences and severing Allied links with Strasbourg as part of Operation Nordwind. He was told there were no plans available of the Line but that it was “barely manned and constituted no obstacle”. However they came up against fierce resistance and concentrated American artillery fire. They had to withdraw on 6 January 1945 and again after another attack on 8 January, although they drove
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