Fortress Europe- European Fortifications Of World War II

by J E Kaufmann

  HISTORY

  After the Great War, the coast defenses were given less attention as Mussolini pursued his dreams of colonial expansion, investing in offensive weapons and units. The plans for the defense of the peninsula during the Mussolini era involved primarily the creation of the Vallo Alpino, because relations with France, Austria, and Yugoslavia were becoming uncertain. The Vallo Alpino was conceived in 1930 when General Guidetti of the Genio, or corps of engineers, was put in charge of studying the situation.

  The creation of the Vallo Alpino began with the renovation of many of the old Austrian forts for use as casernes or ammunition depots and the preparation of new border fortifications. On the French front, the forts of 1870s, 1880s, and World War I vintage with their high profiles, served better as casernes for Alpine units, than as active defenses. Nonetheless, some of them remained armed and were integrated into the defensive system. In the mid-1920s Fort Chaberton awaited the return of the artillery that had been transferred to the Austrian front during the Great War. It also received additional construction. Work on a cavern battery in the face of Mount Chaberton was begun but never completed.

  New construction on the Vallo Alpino began in 1931 and continued for several years to keep up with the French Maginot Line. The Northern Front with Switzerland was untouched, although a number of defensive positions built during World War I remained in service.2 Unbeknown to the general public for many years, fortifications went up on the Oriental Front.; Apparently little was done until late in 1939, well after Italy became Germany's ally, when a serious effort was made to build up the defenses against their Axis partner. Mussolini, apparently well aware of Hitler's ideas in Mein Kampf, wanted to ensure that no attempt would be made to place Trento, with its large Germanic population, in the Third Reich.

  Work began slowly on the Eastern Front when Italian troops were sent to the Brenner Pass in 1934 in response to the attempted Nazi coup in Austria, and continued through 1942. In the spring of 1935, the American consul reported that the Austrian frontier was being fortified from Fortezza to Brnico, Dobbiacco, and Tarvisio. He also noted extensive work in the Adige Valley between Verona and the Brenner Pass where several lines or systems were being built and new positions were being cut into the mountains. The consul also observed new defenses on the Yugoslav border, which, according to Italian military sources, were very light and designed to support offensive operations. He opined that the work had been going on for years and that the military used only Italian laborers for security reasons. This may well be the reason so little is known about these works.

  According to 1936 reports, the Brenner Pass was rigged with explosives wired to detonate when driven over by heavy vehicles. In the spring of 1940, the Swiss press reported the presence of twenty-eight forts in the Brenner Pass. Other observers counted as many as thirty-six to forty-two, despite the excellent camouflage. New roads were built and older ones were widened on all fronts, especially at Tarvisio, near the Austro-Italian border.

  On the whole the Italian defenses were to consist of several lines of defense. The Occidental Front bordering France included two to three lines and the Oriental Front, facing Austria and Yugoslavia, three. The sector bordering Switzerland didn't progress beyond the planning stages but the old positions, blasted into the ground to form the Cardona Line during the Great War, remained serviceable. Thus, on paper at least, the defenses of the Alpine Wall were indeed as formidable as the Little Maginot Line of the Alps.

  While Northern Italy was protected by the Alpine Wall from land invasion, the rest of the country needed protection from air and naval assault. To this end, more than a dozen key areas were selected in the early 1920s. In 1924 the military decided to fortify all major naval bases on the Mediterranean coast and certain strategic ports and economic centers extending from Genoa on the Riviera, to Maddalena on Sardinia, to Naples and Palermo in the south. These places were to receive heavy artillery ranging from 203-mm to 381-mm as well as numerous smaller weapons, including anti-aircraft guns.

  Many emplacements from World War I remained in use until 1943. The battery of Amalfi (381-mm gun turret), one of the positions opened to military attaches in 1922, was equipped with such state of the art equipment as the latest fire control system for modern forts and the Braccialini goniostadiometer that was purported to give the range of targets up to 30 km.

  In 1931 new plans were drawn to improve strategic island positions such as Leros. The first new battery in Italy after the end of the Great War was not set up until 1934 at Maddalena, Sardinia. It consisted of two gun turrets that mounted four 203-mm/45 guns each. In addition, a new type of installation was perfected with all its facilities beneath the concrete structure and armed with 381-mm/40 guns. The first of these batteries, completed at Augusta, Sicily, in 1939, included 381-mm guns. The second battery of this type mounted two 203-mm guns.

  However, the limitations of the national industry, financial restraints, and various other problems did not always permit the fruition of Italy's ambitious defensive schemes. Thus the proposed twin turret batteries for the strategic island of Pantelleria that would have mounted 320-mm and 203-mm guns, were not even built.

  During World War I five army coast artillery fortress regiments had occupied the key regions. Between the wars the number was reduced to three in the 1920s, and replaced by the Coastal Militia in 1935.' In 1938 the Coastal Militia became the Naval Artillery Militia and defended all the major naval bases on the peninsula and Pantelleria. Between 1941 and 1943 the army organized coastal brigades that eventually formed twenty-five coastal divisions.

  DESCRIPTION

  1. The Vallo Alpino

  The Vallo Alpino consisted of three zones. The first was the Zona di Sicurezza, or Security Zone, whose mission was to prevent a surprise attack, impede an enemy advance, and allow the army time to mobilize. This zone included some strong points to stop the enemy as well as smaller outposts. The second was the Zona di Resistenza, or Resistance Zone, which had larger fortifications and whose mission was to continue resisting even after becoming isolated. It included casemates and other types of blocks for artillery, infantry, and observation with, usually, separate entrances. These large positions contained casernes with all the facilities for the garrison beneath the concrete structure. The third was the Zona di Schieramento or Marshalling Area where the artillery and other army units mobilized. This area normally included much of the anti-aircraft defenses.

  The Zone di Sicnrezza included well concealed avamposti (advance posts or outposts) made of concrete and armor. They replaced older avamposti from the last war and may have been stronger than many of the French avant-postes of the Little Maginot Line.

  The Zona di Resistenza, the main defensive zone, contained several of the older forts, some of which served mainly as casernes and/or storage areas and others as active combat positions. On the Occidental Sector, forts like Jafferau and Chaberton, rearmed with 149-mm guns, served as advanced positions. On the Oriental Sector in Trentino, about twenty to thirty former Austrian forts were converted into casernes or ammunition depots. They were located in the Zona di Resistenza as well as the Zona di Schieramento.

  All three main types of Italian fortification were found in the Zona di Resistenza. These works, known as opere, included Types A, B, and C. In Subsector IX/a (Moncenisio) of the Occidental Front, the fortifications extended from Mt. Malamot across the valley, reinforcing or replacing the older defenses from the last war. Fort Malamot's artillery was removed and replaced with 47-mm anti-tank guns in cloches, and lighter weapons. Subterranean works were also added to the fort. Additional work was done on sector IX/a after 1935 when Italy's Ethiopian adventure created more international friction. About thirty of the three types of opere were built during those last few years, and more were on the drawing board.

  An army report of 1942 mentions the creation of defensive barriers consisting of various types of bunkers, probably including all three types of opere, that were to block a valley or pass
age through it. Also, obstacles like anti-tank ditches would supplement these positions. The report noted that in many places, especially on the front with Yugoslavia, many of these positions were not satisfactory because additional work needed to be done to further secure their flanks.

  The largest type of positions, Opere A, normally required much excavation since they were built into the rock instead of exposed buildings like those associated with the casernes. They received the heaviest type of concrete protection to resist heavy artillery. The concrete thickness varied according to the amount of rock cover, but was generally no less than 3 meters of concrete in the areas where the rock cover was not sufficient. The high cost of construction limited the number of Opere A built and completed. Most consisted of five or more combat blocks linked by underground galleries and subterranean facilities with casernes, and other facilities that included a usine for generating power and a heating system. An armored chimney located outside of the opera served the electrical ventilation system and gas proof doors secured each entrance. Although individual positions could be isolated and resist for an extended period of time, they were not intended for long-term occupation. Like the French Maginot ouvrages, they provided basic life support systems with no luxuries. However, they were even more Spartan, only offering the security of being out of harm's way.

  In many cases the Opera A consisted of more than one level but had no special equipment such as monte-charges for moving munitions up to the blocks or engines to pull the carts through the long galleries. Munitions and supplies were moved strictly by manpower.

  The combat blocks received information from observers located in armored cloches. The armament for these blocks included machine guns and, in some cases, 47-mm anti-tank guns. They were usually located where they could effectively dominate an important town or road and were expertly concealed into the terrain.

  A good example of a very large Opera A, also serving as a battery position, was #17 of Gravere, located at an elevation of 930 meters and consisting of fifteen combat blocks.' It occupied the upper part of a mountain and had two entrances leading to two separate galleries linked by several access tunnels. The interior included all the facilities necessary to support the 240 man garrison. This opera consisted of four artillery blocks that mounted a 75-mm gun each and three observation positions located near the top of the mountain. Two blocks for 47-mm anti-tank guns covered the eastern side of the opera, near the entrances. The other blocks of the opera held heavy or light machine guns and defended every side of the mountain. Opera #17 did not have diamond fosses because it overlooked a steep mountain side.

  More common fortifications were the medium opere known as Type B with a maximum of four combat positions but the same amount of concrete protection as Type A. They housed smaller garrisons and contained even fewer interior facilities.

  Some positions designated as battery positions, usually in caverns excavated into the face of a mountain, may also have been included in the count of Type A and B opere. They usually consisted of several artillery pieces mounted in individual blocks linked by a tunnel to a service area and entrance.

  Opera #32 at Moncenisio belonging to Gruppo Gran Croce with two entrance blocks and three combat blocks, is a good representative of Type B opere. Most of its underground facilities were situated midway between the entrances and the combat blocks. Its combat block consisted of a small firing chamber for a single heavy weapon, flanked by a smaller position for a light weapon, such as an automatic rifle. The smaller position covered the facade of the bigger position with flanking fire. In front of the crenels was a diamond fosse similar to those used in France.

  The most common fortifications were the small, Type C opere that consisted of only two combat positions for machine guns or AT guns. Their concrete protection was less than 2.5 meters thick. It was able to withstand the fire of small to medium caliber artillery. The interior facilities of these opera were decidedly limited.

  Opera 15-bis of Gruppo Rivera Rivero, located near Lake Moncenisio, is a fine example of a large Type C. It was a large two-level casemate with the troop facilities on the lower floor. The entrance, located in a rear corner of the upper level, was protected by a caponier-like position with three crenels for an automatic weapon that fired across the entrance, to the front, and the opposite side. Another exit was located on the other side of the opera, just behind the front of the casemate and diagonally opposite of the entrance, and was covered by another caponier that formed part of the front of the casemate. Grenade launchers protected the facade overlooking the front. Small firing rooms for an anti-tank gun and two heavy machine guns gave frontal fires, and two other small crenels for automatic weapons covered the curved face of the block and the embrasures of the main weapons.

  Type A and B Opere, like the ouvrages of the Maginot Line, were built to suit the terrain, and their features were so individual that it is difficult to classify them according to a common standard for size, type of weapons, and organization. What many had in common was the great number of one- or, in some cases, two-weapon combat blocks that occupied a minimal amount of space. Diamond fosses that protected crenels and entrances were also common, except in difficult terrain such as cliff faces.

  Anti-tank obstacles like walls, ditches, and barbed wire, formed part of the defenses where necessary. Many opere included cloches designed either for observation or for weapons of a distinctly Italian style. Many observation cloches were reached by handrails or long stairways since there were no lifts.

  The smaller Type C Opere conformed to no particular standard type but, like the larger works, were superbly camouflaged.

  Financial restraints limited the use of armor so that entrance doors, crenel plates, turrets, and observatories had to be used sparingly. The opere were linked to each other with underground telephone cables, special light signals, and radios. However, the Italian forts were not as lavishly armed or equipped as their Maginot counterparts because of financial limitations.

  The weapons used in the Vallo Alpino consisted of medium artillery ranging from 120-mm to 149-mm guns mostly installed in older forts. Some opere had mortars and even flame throwers in fixed positions. Plans were also made to employ poison gas in some valleys in the event of a successful enemy advance. In some cases additional large anti-tank ditches blocked access to the opere and in at least in one case, at Pont Ventoux, they completely closed off a valley.

  The following is only a partial list of some Italian positions on the Occidental Front to serve as an example of their size and armament:

  Moncenisio area with about 30 Type A and B Opere.

  Gravers area covering Monte Morone and Susa had about 30 opere.

  Gruppo Coma Rossa with

  4 combat blocks -Machine guns and anti-tank guns.

  Opera #21 near Ospizio with

  6 combat blocks -Machine guns and small cannon.

  Opera #19 near Oiano dellaVaccheria with

  5 combat blocks - One small caliber gun and a machine gun in each block.

  Opera #7 under Fort Combe extremely large Type A with

  several combat blocks -Two 75-mm guns, one 65-mm gun, six 47-mm AT guns, two 20-mm guns, eight heavy machine gun.

  Opera #10 near Gravere large Type A with

  9 combat blocks - four 81-mm mortars, three anti-tank guns, twelve heavy machine guns.

  Opera #116 at Cros du Rey

  Some old forts refurbished:

  Fort Bramafan - new machine gun positions and emplacements for two batteries of 149-mm guns.

  Fort Pramand - four 149-mm gun turrets.

  This is only a small sample of the numerous positions on the Occidental Front. The positions described were in the sectors defending the passes at Monginevro (Montgenevre), Frejus, and Moncenisio (Mont Cenis). Smaller works covered the Petit St. Bernard Pass. Additional opere defended the passes of the Maritime Alps, including the key Tende Pass. Here a number of opere were carefully sited to control the terrain. In this area was the large ope
ra of Balcone di Marta with a number of blocks including four with 75-mm guns that formed a cavern battery, and over 1,300 meters of tunnels with elevation between the highest and lowest level of over 100 meters.

  The Oriental Front included about: 50 Type A opere, many incomplete, approximately 160 Type B, and fifty artillery pieces. The armored forts of Montecchio, near the eastern shore of Lake Como at Colico, Il Canale near Tirano, and Venini, near Bormio were also in service. Montecchio-completed in 1915-and 11 Canale had four turrets mounting 149-mm guns while Venini had four turrets with 120-mm guns.

  In 1939, on the Occidental Front of the Alpine Wall, about 460 opere mounting 133 pieces of artillery were manned. At the same time, work continued on all fronts, including the border with the Reich. In some places civilian construction companies worked around the clock as Mussolini prepared to enter the war. By June 1940 the number of occupied forts grew to over 550.6

  By 1942 the frontier with Germany was mostly protected by medium to heavy opere that were better armed than positions on the Western Front. The total number of opere on all fronts of the Alpine Wall by August 1942 increased to 1,475; another 450 were still under construction. In addition, about 700 defensive casernes and shelters were finished and another 60 were still being built. There were also plans to build another 1,400 opere, casernes, and shelters, two-thirds of which were to be erected on the German front.

  The frontier was defended by the Guardia alla Frontiera, or Frontier Guard, that formed eleven commands along the Alpine border and garrisoned the opere. During World War II, the Occidental Front was divided in three sectors under the jurisdiction of three active army corps. The I Corps was responsible for Sectors VI, VII, VIII, IX, X, the II Corps for Sector II, III, and IV, the XV Corps for Sector I and V.

  2. Coast Defenses