Fortress Europe- European Fortifications Of World War II

by J E Kaufmann

  After September 1939, the Swedish government authorized the improvement of the coastal defenses. The main effort centered around five major commands: on the west coast at Goteborg, the south coast at Helsingborg, the southeast at Karlskrona, the Stockholm area, the north coast at Henso, and on the island of Gotland. Every year new positions that included casemates and turrets were put into operation. Between 1940 and 1945, many mobile 150-mm gun batteries with new Bofors weapons were added.

  Each of the major commands set up so-called barrier positions that defended the entrances to major fjords and key coastal sites and included individual batteries and forts. Some of the forts comprised more than one battery, old torpedo-batteries, and the more widely used mine fields. The gun batteries ranged from heavy artillery, of usually 240-mm, to medium weapons such as 120-mm. Some batteries consisted of light 57-mm guns and anti-aircraft artillery of various calibers. The total number of all types of coast-defense batteries was twenty-four in 1937 and rose to forty in 1939 and ninety in 1942. In 1939, fifteen batteries consisted of heavy guns (210-mm and larger). This number rose to twenty-one between 1942 and the end of the war. The number of medium weapons (120-mm to 150-mm) rose from fiftyseven in 1939 to seventy-nine in 1942. These numbers show that Sweden was not as vulnerable as its neighbors were in 1940.

  Between 1940 and 1942 some of the major Swedish coast defense positions were divided into divisions whose main unit was either a major battery position, a fort, or a Sparren or barrier position. The Sparren could contain one or more batteries. The major coast defense positions were distributed as follows:

  In some of the coastal defense positions the weapons were mounted on barbette carriages, but most were in casemates and turrets. Every year stronger positions were created.

  The Per Albin Line was mostly in the Helsingborg command and it consisted of bunkers with two to four machine guns covering one to two flanks. They were designated Ksp I, II, III, or IV (Ksp for machine gun, and the Roman numeral for the building phase). Bunkers designated PV had 37-mm Bofors anti-tank guns. Most positions had an observation cloche. Because of heavy concentration of defenses in this line, some bunkers were only 165 meters apart.

  On the island of Gotland the Tingstade Fortress was the main center of resistance. It was located north of Visby and consisted of six small forts built between 1911 and 1916 which formed a semicircle around the town with the lake on the open side. Only one of these was an artillery fort, and during World war II its four old 84-mm gun turrets remained in operation. The fort's garrison was 300 men. The remainder of the fortress was defended by open concrete machine gun positions.

  Sweden did not dedicate as much effort to its land borders as to the coast except for the Boden area. Five major forts and about a dozen smaller medium and light works formed the fortress ring that had a circumference of about 25 kilometers.' Its garrison consisted of about 25,000 men, both regulars and reservists. The artillery men occupied the forts and the infantrymen the intervals, and sometimes, cave-like shelters outside the forts. The large forts, located on mountains from which they took their names, included:

  -Fort Rodberget at 120 meters, south of Boden on the west side of the river.

  -Fort Gammelangsberget at 126 meters, east of Boden.

  -Fort Mjosjoberget at 115 meters, just north of Gammelangsberget.

  -Aberget at 98 meters on the opposite side of the river from Rodberget.

  -Degerberget at 171 meters to the north of Boden.

  These forts, blasted into the granite mountains, had encircling moats of a depth of over 6 meters and a width of 9 to 12 meters. The forts had one main entrance located above the fosse and, in some cases, more than one emergency exit in addition to the exits in some of the caponiers that protected the moats. The subterranean works consisted of three to five levels and a main gallery in the middle. The only tunnels below the main gallery passed beneath the fosse to access the caponiers. The tunnels were cut into the granite and were not lined with concrete, but in the rooms of the forts the walls were cemented. The roof of the forts consisted of 10 to 15 meters of granite mountainside. The forts included subterranean magazines, a caserne, a usine (power room) and other facilities at different levels.

  Other features included telegraph and power line links that were buried up to a meter beneath the surface. The usine's two diesel engines provided electrical power to the fort. The air intakes were in the moat or on top of the fort. The garrisons, of up to 700 men, had sufficient resources for two months. In some of the forts supplies were delivered by trucks that drove through the entrances. In others they were unloaded at the outside gate because the entrances were too small for trucks. During the construction years, only horses and wagons could reach the building sites.

  Every fort at Boden had light and heavy artillery. The light weapons were 84mm weapons and mortars. They were probably manufactured by Bofors. The forts also mounted 84-mm howitzers, but the number varied with Fort Rodberget having seven and others less. Fort Mjosjoberget had eight 84-mm caponier guns while most others had two. An 84-mm gun with water cooled machine guns (Model M/36) occupied a position in each fort's entrance. Fort Rodberget had seven mortar pits on its surface, but this number varied in other forts. The total number of light weapons may have varied between the World Wars.

  Each of Boden's forts mounted eight single gun artillery turrets. Laborers hauled the large 10-ton gun turret into the forts in four pieces. The armor thickness varied between 60 and 90 cm. The forts of Rodberget and Mjosjoberget each included four 152-mm howitzers in turrets. The range of these weapons was only 10 km. The other three forts, Aberget, Degerberget and Gammelangsberget, each had four 120mm guns in turrets. These guns, probably Bofors M/99 models, had a longer range of 18 km. The remaining four turrets each had carried an 84-mm gun.

  The forts of Boden each had one, possibly two observation cloches which could direct the fort's artillery. A single fixed searchlight position was also created, but later this was replaced with a larger mobile searchlight for use in detecting aircraft.

  One of the medium works was the Mount Svedje Battery, built in 1913 on the same mountain as Fort Gammelaling. It consisted of an eastern and western battery. In 1917, a crew of twenty-five men served the four field guns of the western battery. In 1940 the number of guns grew to six. The eastern battery consisted of two guns. Four more guns were mounted above it. This medium-size fort had no caserne for the garrison, but included a wood burning stove for cooking and heating. The troops slept in the long entrance corridor that held about thirty men. Two fallbersskansen or "sausages" at the northern and southern ends of the fort consisted of infantry positions with rifle embrasures that held 111 soldiers to defend the southeastern flank and support the eastern battery. "Sausages" like these were built along roads leading up to the forts and were on the outside shoulder of the road."

  WEAPONS AND EQUIPMENT

  A variety of weapons were employed in Scandinavia. Denmark and Norway used many foreign models, especially British and German. Sweden, on the other hand, produced many excellent weapons of its own.

  WORLD WAR II

  When Germany struck in April 1940, Denmark was unable to resist. Its army and coastal batteries offered virtually no opposition against overwhelming odds. If the Germans had been challenged by the Danish coastal batteries, the occupation of the main islands would have been costly. However, a German troop ship sailed right past the forts of Copenhagen and landed its cargo of assault troops unchallenged.

  Norway had made some preparations since the war began by 1940 while trying to maintain its neutrality, but last-ditch efforts were of little avail. The key fortress of Oscarsborg held fewer than 300 men. The other four forts of the Oslo Fjord Fortress were hardly better prepared. At Kristiansand there were only about 400 men despite the preparations made in 1939. The 65-mm guns of the shore battery were not even manned when the invasion began. The situation at Bergen and Trondheim was equally precarious. Narvik's defenses were almost non-existent.
The Germans easily entered the fjord only to be challenged by a pair of old coastal defense ships that were quickly dispatched. German troops landed at the entrance of the fjord and quickly took the forts of Ramnes and Havnes, reporting later that they consisted only of a few partially completed bunkers. German planners, who had hoped to use these forts to protect the fjord from an Allied attack, concluded that they could not implement their objective.

  The story of the German invasion of Oslo Fjord is well known. The flotilla first encountered the little guard ship Pol III, then sailed through the fog, past the guns of Fort Bolaerne, until it was challenged late in the evening of April 8, 1940, by Fort Rauoy. Unharmed, the invaders sailed up the fjord until, shortly after 4:00 AM, they came within firing range of Fortress Oscarsborg. Despite the fact that there were not enough Norwegian gunners to fire and reload the three 280-mm guns of the Main Battery, the German cruiser Blucher was hit by the first shots of the Main Battery and then by the 150-mm guns of Kopas Battery. After taking two hits from 280-mm rounds, thirteen from 150-mm rounds, and thirty from 57-mm rounds, the German warship sailed beyond the reach of the guns only to be struck by two torpedoes from the ancient Torpedo Battery. About one hour after the first salvo of the battle, the Blucher went down. It was the first major success achieved by coastal guns during the war and probably the only one by a coastal torpedo battery.

  The Norwegian gunners at Oscarsborg next directed their fire against the cruiser Liitzow, scoring three hits with 150-mm rounds and knocking out its forward gun turret before the Germans withdrew. Later, German troops landed further down the fjord and took the Husvik and Kopas Batteries before forcing Oscarsborg to surrender on the next day. Meanwhile, in the afternoon of April 9, Fort Rauoy was captured and the Germans turned its guns on Fort Bolaerne. On April 4, the remaining forts surrendered even though most took no part in the battle.

  The story was repeated at Kristiansand, where, on the morning of April 9, a 150-mm round struck the German cruiser Karlsruhe as it led an invasion force to within 6,000 meters of its landing site. After a brief exchange of fire with Fort Odderoya, the Germans retired and waited for air support. About an hour later, at 6:00 AM, a second German attempt was rebuffed again. The cruiser finally withdrew beyond the range of the coastal guns and began bombarding the town but missed the fort. An air attack detonated a magazine at the fort, then a third attempt was made at 10:00 AM. The Germans finally succeeded thanks to an error in judgment. Believing that they were French ships, the Norwegians allowed the vessels to land at the harbor, realizing too late that they carried German soldiers. With no supporting infantry, the Norwegian garrison had to surrender. Errors and confusion had prevented the Gleodden Battery from firing.

  At Bergen, German troops landed at the entrance to By Fjord at 4:30 AM to take out the batteries of Kvarven guarding the passage. The cruiser Koenigsberg led the German squadron. At 5:15 AM the Norwegians opened fire, hitting the cruiser three times and a supporting ship once, as they sailed past the battery. The Sandviksfjell Battery fired on the cruiser Koln, but the German cruisers and aircraft forced it to give up. The defenders of Bergen surrendered late in the morning, but not before another German cruiser was disabled. Less heavily protected seaports such as Arendal, Egersund, and Stavanger fell quickly.

  At Trondheim a German task force, led by the cruiser Hipper, slipped past the searchlight batteries of the forts of Brettignes and Hysnes. The guns of Fort Hysnes opened fire on the accompanying German destroyers, forcing the cruiser to fire back as three destroyers landed troops to attack the batteries. The Trondheim forts remained under Norwegian control on April 9 despite the loss of the city.

  As the German invasion force moved inland toward Oslo, the forts of the Fossum Fortress went into action. Forts Tregstad and Hoytorp, like most of the frontier forts, had either no garrison or only a caretaker force. Nonetheless, they fired their 120mm gun turrets on the Germans between April 13 and 15. They were forced to surrender after they expended all their ammunition.

  The little fort of Hegra, on the road to Sweden from Trondheim, distinguished itself when Major Reidar Holtermann organized a motley force of Norwegian volunteers that quickly grew from fifty to two hundred men. Holtermann prepared the 75-mm and 150-mm guns and the snow-covered positions of the fort for battle. Despite the fact that the fort's guns could not be aimed at the railway to Sweden, the fort continued to resist, even after the Germans had cleared it with an armored train. One German attack was repelled as the garrison prepared to fight in the galleries. The main assault came on April 23, but failed. On April 25, the Germans simply gave up the idea of taking the fort, which finally surrendered on May 5.

  The Norwegians demonstrated that obsolescent coastal defenses and forts were still effective in modern war. Had they been properly defended and prepared, they would have exacted a far heavier price from the Germans.

  Sweden's many coastal positions and land forts were better prepared than Denmark's and Norway's. Surprisingly, on April 9, 1940, the Per Albin Line was not even manned and many of its positions had not even received their armament yet. The Swedes soon reacted. Although the Germans prepared an invasion plan for Sweden, their associated naval operations were less ambitious than those under taken in Norway. They only scheduled a couple of landings in lightly defended areas because they had learned their lesson in Norway, where they had already lost a number of vessels.

  In February 1943, the German commanders in Norway were instructed to prepare plans for the occupation of Sweden in the event of an Allied landing. The first of the two main invasion routes considered was east of Oslo, into southern Sweden and Stockholm. The other line of advance was from Trondheim to the Gulf of Bothnia, to prevent the allies from making contact with southern Sweden, assuming an Allied invasion force advanced from Narvik to Kiruna.

  The Germans, who thought that two successive lines of defenses faced southern Norway, along Lake Vanern, planned to bypass them by moving across the border, to the northeast of Oslo and down the Klaralven River. They also believed that there was a line between Lake Vanern, via Filipstad, to Ludvika, Falun, and the sea and a fortified zone around Stockholm as far West as Vasteras and Avesta, forming a semicircle about 200 kilometers long.

  Thanks to its efforts to strengthen the coastal defenses and the army after April 1940, Sweden saved itself from invasion. During 1941 the Germans pressured the Swedish government to allow troop trains to carry German units from Norway to Finland through Sweden. The forts of the Boden fortress kept their guns trained upon the German trains to prevent the type of surprise-operation that had distinguished the Germans earlier in the war. As the war progressed the Germans committed themselves elsewhere, making it impossible to undertake a major campaign against the improved defenses of Sweden.

  280-mm gun of main Battery of Oscarsborg Fort. (Svein W. Olsen)

  Frontal view of 280-mm gun "Moses" of Main Battery of Oscarsborg Fort. (Svein W. Olsen)

  210-mm Gun Emplacement at Ft. Kvarven, Bergen. The German 150-mm SK U45 replaced it. Note observation position to its right. (Svein W. Olsen)

  Ft. Kvarven, Bergen. Torpedo Battery, similar to others used in Norway and Yugoslavia. These were old positions from the last century in many cases. (Svein W. Olsen)

  Map of Norway, Sweden, Finland

  Example of fort at Boden.

  Denmark

  Chapter 9

  CZECHOSLOVAKIA

  BACKGROUND

  Czechoslovakia's history as an independent nation began after World War I. During the nineteenth century its key components, Bohemia, Moravia and Slovakia, had been under the control of different empires. Bohemia, once called the "Cockpit of Europe" by Otto von Bismarck, had formed part of the Austro-Hungarian Empire. It had no modern fortress rings but many older fortifications dating from the Renaissance and earlier because other Austrian territories had shielded it in the last century.

  When it gained its independence, Czechoslovakia found itself faced with hostile neighbors. I
ndeed, Germany and Austria felt that too much of their territory had been taken to create this new nation. Furthermore, in 1919 Czechoslovakia incurred the enmity of Poland when it seized its territory of Teschen (Cieszyn) at a time when the Poles were engaged in a life or death struggle with Soviet Russia. Finally, on the southern border, the Hungarians were trying to reclaim some Slovak territory, which, they felt, were rightfully theirs.

  To hold its enemies at bay, in the 1920s Czechoslovakia formed a rather tenuous alliance, known as the Little Entente, with Yugoslavia and Rumania with the tacit support of France. This move succeeded in holding only Hungary at bay but failed to impress Germany, Austria, and Poland. By the 1930s, after the rise of Hitler, the Czechs, realizing that the mountainous border region was no longer sufficient to shield them from the two German states, decided that it was critical to create a defensive barrier.

  The length of the Czech border made the creation of a continuous fortified barrier difficult. It consisted of approximately 1,100 km on the German side, 400 km on the Austrian, and 600 km with Hungary. The 200 km long Rumanian border did not necessitate defenses and the 700 km Polish border was easily defended for most of its length by the Carpathian Mountains. Thus the Czechs were faced with a Herculean task, especially with the onset of the Great Depression.

  MAJOR FORTIFICATIONS

  The Czech Maginot Line or Benes Line

  The Slovak Defenses