Fortress Europe- European Fortifications Of World War II

by J E Kaufmann

  In addition to the bunkers and the blockhouses, the Border Line included forts built after the Great War. Each of these forts consisted of machine gun blocks and normally included two gun casemates mounting a single 75-mm gun. Fort Pre-Giroud had an additional 75-mm gun casemate that housed a 47-mm anti-tank gun. Fort Heldsberg, larger than the others, had four 75-mm gun casemates instead of the regulation two. The Swiss border forts were much smaller than the French Maginot ouvrages and had smaller blocks and subterranean facilities. Their entrance block was normally combined with a machine gun block. Where possible, one block was outfitted with an escape exit. The Swiss forts were not as strong as the French forts and they probably would not have withstood heavy bombardment as well as the Maginot forts.

  Fort Pre-Giroud, built on a mountain slope, dominated the railroad tunnel through Mont d'Or and the Joux Valley at Vallorbe, across from the French border. Some of its blocks, like those for the 75-mm guns, were camouflaged as rock outcroppings and had no close defense weapons. The machine gun blocks were disguised as chalets.' Wire obstacles and concrete anti-tank barriers covered the approaches. The garrison consisted of about 100 to 150 men.

  The new Swiss forts had some standard features in common. For instance, they had two-level gun casemates with the firing chamber on the upper level, and machine gun blocks with firing chambers on one or two levels. However, there appears to have been no standard for the location of blocks and facilities. Thus at Pre-Giroud the caserne, usine, and all other facilities were located 30 meters below the entrance where feasible. In addition, the caserne was a two-level complex behind and below the entrance. At Fort Reuenthal, on the other hand, the caserne consisted of several single-level chambers because the fort was located on the hills overlooking the Rhine and it had not been practical to dig out deep and extended galleries. Furthermore there were two magazines at Pre-Giroud, but only one at Fort Reunethal.

  The equipment of the forts, ranging from diesel engines, to ventilation systems, and weapons, was relatively standard. A decontamination shower was placed in the entrances. An underground telephone system linked the fort to other units. The weapons included old models of water-cooled machine guns and the 75-mm guns of the latest design. A pantograph with an attached magnifier was mounted on the machine gun and cannon to help aim the weapons at targets in the surrounding area.

  In the blocks of the forts there were special hookups for the crews' gas masks that supplied the men with oxygen. There were also hand-operated ventilators. Power was supplied by an usine in the fort and by the civilian grid to which the fort was hooked up by cables. Each fort maintained two months worth of supplies.

  The forts included: Pre-Giroud Plainbois Reuenthal Ebersberg Heldsberg 3 blocks for 75-mm guns 2 MG blocks 2 blocks for 75-mm guns ? MG blocks 2 blocks for 75-mm guns 3 MG blocks 2 blocks for 75-mm guns ? MG blocks 4 blocks for 75-mm guns 5 MG blocks

  At least one infantry fort, Fort Flueholz near Baden, somewhat similar to the Border Line fort's but without artillery was built on the Limmat River section of the Army Position. Actually three artillery forts with gun turrets were planned in the Limmat sector since 1938, but none were built as a result of the German attack on the Eben Emael. The military felt that line gave them more flexibility in holding back an invasion.

  Ethnic and linguistic diversity, a problem unique to Switzerland, was solved by assigning French-speaking crews to the two forts along the Jura, where the local language was French, and German-speaking garrisons to the forts located in German cantons.'

  2. The National Redoubt

  The National Redoubt contained the greatest variety of Switzerland's defenses: from the largest forts to the blocking positions prepared for demolition. After the war began, more forts were built in the redoubt. Even as the twentieth century comes to a close, and most of the forts in other countries have slid into obsolescence, a number of the Alpine forts in Switzerland have been refitted with modern weapons and their number, size, and locations remain officially secret.

  When World War II began, Switzerland was near completing or had completed twelve new artillery forts, five of which covered the important northern and western fronts. There was one fort at Tessin, one at Grisons, and four in Valais and Fortress Sargan. Nineteen large artillery forts were under construction and cavern positions for older 75-mm field guns were being prepared. The weapons mounted in the new forts included 75-mm, 105-mm, and 150-mm guns. The 150-mm gun was not installed until late in the war and still remains in service. Some of these forts even mounted cloches.

  Today Fort FUrigen, one of the small forts guarding the approaches to the redoubt, is open to the public but it probably is not typical because it was built into the rock, over the lake shore near Lucerne. It includes three machine gun blocks, one of which is located at a higher elevation than the others and is equipped with a searchlight. The fort also has two 75-mm gun blocks that include an observation position. It has the same facilities and equipment as the border forts, but its layout is very different.

  The Fortresses of St. Gotthard and St. Maurice contained the oldest forts, built at the end of the last century. Their artillery included:

  In the redoubt special caverns were carved out in the mountains to accommodate small magazines and store anti-tank guns, machine-guns, and munitions. Two to four rows of holes were drilled and capped in narrow defiles to create anti-tank obstacles similar to those used on the bridges. In certain narrow passages small chambers secured by a door were prepared and loaded with explosives, ready to be detonated by the local militia. The rail tunnels were also readied for destruction. Thus passage through this Alpine fortress was easily controlled and blocked with a judicious use of forts and explosives.

  WEAPONS AND EQUIPMENT

  Much of the equipment for the new forts was locally produced, especially the weapons and optical instruments. However, armor plate for the border forts initially came from the German Krupp Works, but slow or delayed deliveries before and during the war forced Switzerland to produce its own. Many of the cloches for machine-guns and observation for the National Redoubt were purchased from Czechoslovakia, about a year before the Munich Crisis. However, the turrets for 105-mm guns, the guns themselves, and the 75-mm anti-aircraft guns were manufactured in Switzerland. The 75-mm ant-aircraft guns were built under license from the French Schneider Creusot Company. The 105-mm and 150-mm guns were produced under a license from the Swedish Bofors Company. The 75-mm guns, used in casemates (BK or BunkerKanone), were designed in Switzerland but derived from the Bofors 75-mm mountain gun.

  WORLD WAR II

  The Swiss army mobilized as soon as the war began. In 1938, secret talks concerning a French advance into Switzerland to head-off a possible German attack took place between the military leaders of both countries. Some Swiss officers inspected the Maginot Line and information was exchanged.

  During the summer of 1939, the army took over the newly completed border forts and the frontier brigades took up defensive positions on the border. However, many soldiers returned home during the Phony War but the defenses remained fully manned. In March 1940 about 60,000 border troops returned to active duty. It is at this time that the Swiss fortifications caught media attention. The press coined the name of Winkelried Line for the Army Position or, perhaps, for the Army Position and the Border Line combined.

  After the collapse of France in the summer of 1940, the Swiss commander-inchief, General Guisan, decided to concentrate on the defense of the National Redoubt since the country was now surrounded. Since he did not think that the border could be held for more than a couple of days, he decided to redeploy the army. At the same time new infantry and artillery forts and other defenses were added to the redoubt. In addition to casemated artillery, a number of turret positions in the rock with underground facilities were set up. Swiss manufacturers produced new 75-mm, 105-mm and 155-mm guns for these positions, replacing the older 120-mm and 150-mm howitzers.

  Nonetheless, the frontier positions were no
t abandoned and additional work was done there. By 1941 Fort Pre-Giroud received three new bunkers that were not connected with underground galleries. At Fort Reuenthal a non-linked bunker with a 47-mm anti-tank gun was added. Some forts, such as those in the Redoubt, re ceived Bofors anti-aircraft guns. Finally, in 1942, the Corps de Garde de Fortifications replaced the border brigades in the fortifications.

  Switzerland's war preparations were not unwarranted. Indeed, the German General Staff had drawn up "Operation Tannenbaum" for the invasion of Switzerland in 1934. The 1940 version of the plan involved a surprise assault that would bring Switzerland to its knees within one week with the participation of only eleven divisions and an Italian army attacking from the south. Documents show that the German strategists were concerned about their ability to take the Swiss border forts, which indicates that there might have been intelligence gaps on the subject. If the German invasion had materialized, the Swiss would most likely have destroyed many vital points on the lines of communications, such as tunnels, crippling the main rail routes between the Reich and Italy. This contributed to the Germans abandoning their invasion plans.

  Ft. Reuenthal on German border near Koblenz (Switz.).The guard post and entrance, located beneath the large MG block (see plan). (Kaufmann)

  Swiss 75-mm fortress gun on mount inside an artillery block. Note the metallic map above the gun with a pointer and magnifying glass which shows where the weapon is pointed. The Czechs used a similar device on their weapons, but the French did not. (Kaufmann)

  Ft. Pre-Giroud. One of the fort's MG blocks covered with artificial metal trees for camouflage. (Kaufmann)

  Ft. Pre-Giroud. Main gallery leading down to one of the fort's 75-mm blocks and a MG block. (Kaufmann)

  Standard Heavy Swiss Bunker for MG and AT Gun. Built 1940.

  Three Swiss Border Forts:

  Chapter 6

  GREAT BRITAIN

  BACKGROUND

  For centuries Great Britain depended on the sea for its first line of defense. Ever since William the Conqueror's successful invasion in 1066, no force larger than a raiding party had struck the British coastline. Napoleon Bonaparte's planned invasion in the early 1800s, which never materialized, forced the British to prepare for war on their own shores. When Napoleon III took power, just as the steam powered ship increased the capabilities of the navy, the British became alarmed again. So the army undertook the construction of coastal defenses. However, by the 1880s Parliament reaffirmed its confidence in the navy, allowing it to remain the first line of defense.

  By the turn of the century, however, the winds of war were sweeping through Europe again and Britain deemed it prudent to prepare for the protection of its empire. Thus the Committee of Imperial Defence was founded in 1904 and given the task of advising the prime minister on the best means and methods of defense. Nonetheless, little changed in Britain's defensive policy, since on the eve of the Great War the Committee was still declaring that:

  The maintenance of sea supremacy has been assumed as the basis for the system of Imperial Defence against attack from over the sea. This is the determining factor in shaping the whole policy of the defence of the Empire and is fully recognized by the Admiralty, who have accepted the responsibility of protecting all British territory abroad against organized invasion from the sea.

  The first significant shift in British defensive philosophy occurred during World War I, when fortified positions went up on the coast. These new positions included battery positions with modern weapons as large as the 9.2-inch guns, emplacements for land-launched torpedoes, pillboxes or bunkers, and barb wire obstacles near likely landing sites.' Trenches created Stop Lines beyond the likely invasion sites such as the vicinity of the Medway. A mine barrage across the Channel blocked the passage of German vessels during the war.

  The advent of the airplane brought a new element to the defenses of the Britons, who concluded that aircraft must become the first buffer against invasion.

  The other key British positions in Europe requiring special attention included Gibraltar, acquired during the War of the Spanish Succession early in the eighteenth century, and the island of Malta taken from the French in 1814. These two outposts guarded the route to the Suez Canal and allowed the Royal Navy to maintain a presence in the Mediterranean.

  MAJOR FORTIFICATION

  Coastal Defenses

  The Stop Lines

  Gibraltar

  Malta

  LOCATION

  1. Coastal Defenses and Stop Lines

  Great Britain was divided into six commands in addition to the London District. The Scottish Command covered Scotland, the Northern the east-central half of the island, the Western Command the west-central half, the Eastern Command the area between the Wash and the Thames, the Southeastern Command the coastline of Kent to Portsmouth, the Southern Command the area from the Isle of Wight to Land's End, including many of the sectors of the GHQ Line.2 The main beach defenses and Stop Lines occupied the southern part of the island south of a line running from the Wash to the Bristol Channel.

  The majority of the coastal positions protected the south and east shores of England, from Cornwall to Northumberland. A large part of the coastline between Devon and Kent was dominated by the cliffs that are part of the white chalk hills behind the coastline. A number of excellent ports on the south coast were the probable targets of any invader who would need to secure them to establish a supply line. A German invasion force attempting a landing on the south coast of England would have faced many of the problems faced by the Allies after 1941. However, the English coastline had a greater concentration of ports suitable for the establishment of a secure beachhead.

  The east coast was less favorable to invasion even though its concentration of major ports was similar to the south coast's. Indeed, its ports were not as evenly distributed so that the defenders would be able to concentrate their defensive efforts around clusters of harbors. Further north, the Scottish coast, with its jagged coastline broken by numerous sunken valleys known as lochs and firths, was less vulnerable. The west coast of Great Britain, which consisted of Welsh, English, and Scottish territory, was also rugged in many places. Its major ports were concentrated in a few areas.

  The advent of air-power turned these sections of Great Britain into secondary targets. Before the war, the British had been uncertain of Germany's capabilities as they planned their own defenses. However, it became apparent in 1940 that no German invasion force would be able to penetrate very far north as long as any part of the Royal Air Force (RAF) remained operational because it would be far beyond the range of its own air support. Fortunately for Great Britain, the pre-war planning became irrelevant because no major work was begun until 1940.

  The western part of England, most of Wales, and Scotland was mountainous. Much of the heavy industry was concentrated in the west and central part of England, in the Midlands. This allowed some room for maneuver in the event of an invasion of the south coast. The GHQ Line, which ran between Bristol and London and was to be extended northward to Edinburgh, was located 25 to 80 km behind the coastline. It was considered the final defensive position that could be held or Stop Line. In addition to the GHQ Line, a number of smaller Stop Lines were prepared by lower formations of the army, such as corps, who made the most of the terrain located between the coast and GHQ Line.

  2. Gibraltar and Malta

  Gibraltar and Malta guarded the line of communications through the Mediterranean to the Suez Canal. Gibraltar allowed the British to control Axis shipping into or out of the Mediterranean. Although submarine transit could not be effectively blocked from Gibraltar, it could be made difficult. The anchorage on the "Rock" sheltered a sufficient naval force to stop the passage of surface units with the help of the artillery.

  The limestone mountain of Gibraltar, honeycombed with caves and manmade tunnels, occupied much of a peninsula little more than a kilometer wide and no more than about 5 km long. The mountain rose sharply from the sea on its east
side to a maximum elevation of 426 meters. The town and anchorage were found along the western, more gently sloping side of the mountain. The only low ground was on the north end of the peninsula, where more than half of the airfield extended into Gibraltar Bay.

  Located south of Sicily, the islands of Malta and Gozo served as a British base. Thanks to the advent of aviation, they were at the mercy of whoever controlled Sicily. The main city, Valletta, occupied the site of the Grand Harbor, strategically the most important part of the island. A number of large bays were found around the hilly island offering potential invasion sites. The beaches between Valletta and St. Thomas Bay on the southeast coast, and those between Valletta and St. Paul's Bay on the east coast were the most vulnerable invasion sites. The southwestern coast included a large area of beaches suitable for invasion, while the hills in the west precluded any type of major operation in that area. The north had only a few suitable landing beaches. Southern Italy could easily serve as an assembly area for an invasion force, which had only a short distance to travel to reach Malta.

  HISTORY

  1. Coastal Defenses and Stop Lines