by J E Kaufmann
1. The East Wall
The East Wall was the heaviest pre-war fortification system built by the Germans, who concentrated the largest positions on the OWB Line. The weapons, equipment, and construction materials were tested at a secret engineer site northeast of Magdeburg, which included the Wandern and Hillersleben testing grounds in the Krupp Polygon. The East Wall positions served as prototypes for the positions on the West Wall and other places.
The OWB Fortified Front, which consisted of three sectors and blocked the direct route to Frankfurt and Berlin, was the heart of the East Wall. Its 16-km long Central Sector contained a number of strong points or werkgruppen that formed the core of the OWB Line. After 1936, many of these Werkgruppen were linked to the vast tunnel system, which was excavated by civilian labor. The 27-km long Northern Sector consisted of a few Werkgruppen and a number of water defenses. The 34-km long Southern Sector relied heavily on defensive terrain and water obstacles, including fourteen dams and sluices. The OWB numbered a total of eleven Werkgruppen that consisted of B-Werke linked to each other by underground tunnels.' Smaller bunker positions and individual bunkers and associated anti-tank obstacles also occupied the entire front. The entire OWB Line consisted of just over 100 positions, including heavy works. There was an advance line at about 10 to 12 km in front of the main line and a third line at about the same distance to the rear, but the latter only comprised a few small structures.
A German fortress battalion trained troops for garrisoning the East Wall, but the only positions that needed a permanent garrison were the Werkgruppen. The individual bunker positions were designed for field troops who only needed to provide maintenance and technical support when the positions were unoccupied. This was also true for the fortifications of the West Wall and accounts for all the simple instructions found painted on the walls of even the oldest bunkers. These inscriptions enjoined the soldiers to "close the armored shutter while using the latrine" to prevent the enemy from seeing the light, not to block vents, and to take other such practical precautions.
The Pomeranian Line covered a larger front that extended for about 275 km and included several thousand positions and eight Werkgruppen.b Like the OWB, it comprised three lines: the main line sandwiched between a forward and a rear line of light bunkers. The positions consisted of small bunkers with anti-tank gun shelters, like in the OWB Line. The underground links of the Werkgruppen were not as long or as deep as those of the OWB Line, and often consisted of a single Panzerwerke with detached cupolas.
A total of twelve Panzerwerke were built in the Pomeranian Line. These twolevel structures had 1.5 meter thick concrete walls, housing a garrison area and usine on the lower floor and usually two weapons positions behind steel walls, and a half cloche on the upper floor'. They accommodated a garrison of about thirtyfive men. Only a few Panzerwerke were not an integral part of the eight Werkgruppen of the Pomeranian Line. In many cases, the Werkgruppen had bunkers that were not classified as Panzerwerke. In general, no specific name was assigned to the Werkgruppen, which are referred to in current literature by the name of their location:
The Oder Line spanned about 150 km, excluding the lightly defended area of Upper Silesia', and numbered no heavy works among its 778 positions. Its first line of bunkers went up on top of the dike of the Oder River between 1930 and 1932. Even though it was vulnerable, this line continued to be integrated into the defenses of the area. A second line of smaller bunkers was erected about 10 km behind the main line. Later, more bunkers were added to the main line. However, this time they were built into the dike, in less conspicuous and vulnerable positions. In most cases their weapons were able to cover each other's flank and fire along the river. All the bunkers had a single level, and every third bunker mounted an observation cloche that barely rose above the surface. All in all the Oder Line consisted of small, light bunkers for heavy and light machine guns, troop shelters, and observation posts. The river served as the main obstacle but at certain points, such as bridges, the defenses were heavily reinforced.
Before 1935, the Germans devised a classification system for defensive works for both East and West Walls based on concrete thickness. Four main types of construction were established: Type A (the heaviest), Type B, Type C, and Type D (the lightest). Type A structures had roofs 3.5 meters thick (although a variant, Al, was not as thick) while those of Type D had a concrete thickness no greater than .30 meters. Types C and D were discontinued after the summer of 1940 because they were considered to be too weak.
This classification system was also extended to the armor plate. Thus Type A armor was from 400-mm to 600-mm thick while Type D positions used nothing greater than 20-mm. It must be noted that the thickness of Type A concrete, 3.5 meters, was identical to the thickness of the heaviest French positions. Nonetheless, the French and the Germans used different methods of concrete mixing and reinforcement, coming up with far different results. Thus Type A armor could resist weapons of 520-mm and direct hits from 1,000 kg bombs while the French walls could only withstand guns of 420-mm. Except for a bridge position on the autobahn between Berlin and Konigsberg, no Type A positions were completed on the East Wall.
Since most German Type A positions, with the exception of a few on the West Wall, never passed the planning stage, Type B became by default the more common type of position. Called B-Werke, Type B positions were capable of resisting a single 300-mm artillery round and continuous fire from 210-mnm guns and withstand a hit from a 500 kg bomb, as Hitler had desired. The older variants of Type B, only 1.0 meter thick, could only withstand bombardment from 150-mm artillery pieces. The old Type C could resist weapons under 105-mm caliber while the Type D could only stand up to the lightest weapons. However, Types C and D could not withstand any direct bomb hit.
The Pnnzerzverke made up most of a fortified group, known as Werkgruppen. Panzerwerke were single- or multiple-level structures usually designed to fire in all directions, mounting their armament in the roof. This armament normally consisted of one or more heavy machine guns and, on Hitler's insistence, also a flame-thrower and a mortar after July 1938. However, only a few dozen flame-throwers and mortars were actually installed.
A 50-mm breech loaded automatic mortar (designation M-19 automatic granade launcher) with a frequency of fire of 30 to 60 rounds per minute, was developed for mounting in a cloche flush with the ground'. It was operated by an officer and seven men, including a gunner and two assistants on the controls in the cloche.
The rotating nozzle of the flame-thrower projecting through the steel collar and mounted in the roof, was able to spray its flames in a full 360 degree arc on the surface. Its fuel supply was stored in a large room beneath the control room. In a few rare instances the fuel room was on the same level as the control room. The whole mechanism was operated by a three-men crew.
Each Panzerwerk needed its own power source to operate some of its specialized weapons and other supporting equipment. The Panzerwerke that formed part of a Werkgruppe received their power from an usine located in the subterranean facilities. The automatic weapons could also be operated manually, but with less efficiency.
The entrances to the Panzerwerke usually consisted of an "L" shaped hall with a decontamination shower at the end nearest the outside entrance. Another armored door with a crenel for small arms at the other end of the corridor, covered the entrance. In addition, part of the entrance floor leading to the interior door consisted of a trap several meters deep that was exposed when the floor was pulled up like a drawbridge to cover the interior doorway. These positions had garrisons of 50 to 70 men.
None of the Werkgruppen had rotating turrets, but had full (six embrasure) on the roof and/or half (three embrasure) cloches projecting from a wall instead.10 The ubiquitous cloches, found in most major fortification of Europe of the time, varied in size and function. The smallest were an observation cloches and the largest, in France, were capable of holding a small cannon. The cloches of the Panzerwerke were among the largest in Europe.
They had six crenels for two heavy machine guns that could be rotated to each crenel individually and small observation points for periscopes in between. Many had a small roof periscope and a searchlight (used in the weapons embrasures) with a range of about 300 meters. Several men occupied the rotating floor with two serving each machine gun. The cloche was made of chrome molybdenum steel with about .5% to .7% molybdenum content imported from the U.S. The first cloche was tested in late 1934 at Meppen, and installation began in 1938.
The half cloche was not set above the roof of the bunker, but projected from the wall, its roof jutting just below that of the bunker and its rear opening into the bunker. Its three embrasures together could cover almost 180 degrees.
The weapons rooms for heavy machine guns and anti-tank guns were actually armored casemates with a steel plate wall and sometimes a similar armored plate roof. The main weapon in both cloche and casemate was a machine gun, but casemates with 37-mm and 50-mm anti-tank guns, and 105-mm guns were projected.
Most Werkgruppen had underground facilities that included a caserne area with all necessary facilities such as the living quarters, usine, and storage areas. The subterranean facilities were located between 15 to 20 meters below the level of the Panzerwerke and were connected to them by a staircase and an elevator. The whole position was gas-proofed with filters and airtight doors. A transformer room located at the lower level of the Panzerwerke converted power from the civilian grid. Each Panzerwerke included one to three emergency exits that led to the surface and were filled with sand that had to be shovelled out before use. These positions, and most bunkers, were connected by underground telephone lines. Few Werkgruppen had special entrance blocks like the Maginot ouvrages. Werkgruppe Ludendorff in the Northern Sector is a rare exception to this rule. Plans were made to connect most Werkgruppen in the Central Sector that had two to four Panzerwerke, to the underground tunnel system. Seven of the nine Werkgruppen in the area were actually linked to it.
On the East Wall, 83 Panzerwerke were completed, 41 of which were located in the Central Sector of the OWB Line. Of these, 23 were grouped into 9 Werkgruppen. The Northern Sector included 24 Panzerwerke, 8 of which formed 3 Werkgruppen. The Southern Sector comprised 18 Panzerwerke that could also be classified as BWerke, 4 of which formed a single fortified group:
WERKGRUPPEN Northern Sector Ludendorff Roon Moltke Central Sector Schill Nettelbeck Li tzow York Gneisenau Scharnhorst Friesan Jahn Korner (no tunnels) Southern Sector Lietzmann NUMBER OF BLOCKS 6 1 1 3 3 4 5 2 3 1 4 3 4
The fortified group of Ludendorff was the first to be built and was used to test new types of Panzerwerke. By 1944 it included five Panzerwerke and a special entrance block. Werkgruppen Roon and Moltke were unusual in that both consisted of a single Panzerwerke, but had underground works and two detached cupolas. A tunnel of about 30 meters connected Moltke's two detached positions, consisting of half cloches, with the Panzerwerke. The usine and caserne occupied the lower level of this large bunker. Additional positions were added to the defenses as the Russians advanced westward in 1944.
One of the most striking features of the East Wall was the vast tunnel system built in great secrecy in the Central Sector that would have become a veritable underground city if it had been completed. The German engineers took advantage of the numerous old mine shafts that honeycombed the area, connecting some of them to form the tunnel and using others as dumps for the spoil from new excavations. Workers completed 32.5 km of underground works and more were planned.
The main galleries were wide enough to accommodate an underground railroad that was to extend for several kilometers. A small underground train would haul supplies from the entrances to the access galleries leading to the various Werkgruppen. Only a small section of track was laid and the train engine and cars were never delivered. The main tunnel of the underground system, 4.0 meters wide and 4.2 meters high, included twenty-two stations spread over a distance of about 10 km. The entrances to the tunnel were located over 2 km behind the main line. The secondary galleries were smaller and led to chambers for two-level magazines and casernes and usines for four to six diesel engines. The subterranean works were located 20 to 40 meters below the surface. In 1938, as most of the tunneling was being completed and the equipment was being installed, Hitler demanded all work to cease. Thus none of the entrances with level access, allowing trucks to drive straight in, were completed. All heavy loads had to use the elevators that were part of the positions already completed with the Werkgruppen. At key points in this complex blockhouses and iron gratings controlled access. Efficiently designed water drains beneath the floor kept the galleries dry and are still mostly functional today. Ventilation was assured through eleven tall chimneys towering above the complex. In accordance with German military planning, the entire elaborate system was primed for destruction thanks to special niches for explosives located throughout the network of galleries.
When he visited the project, Hitler concluded that it was a massive waste of resources, particularly because the dozen Werkgruppen connected with the tunnels mounted only light armament. Actually several large Panzer batteries were planned and would have been installed in A-Werke of three individual blocks mounting a single 105-mm turret gun each. Seven of these batteries were projected for the Central Sector, which was also supposed to include four similar batteries of 150-mm howitzers. The turrets, similar to those used on the Feste, were non-retracting and were designed for long barrel weapons. Each cupola was to be mounted on the end of a rectangular-shaped block. Each battery would have required about 470 men. Work actually began on Panzer Battery 5 and the foundations for a couple more blocks were poured by 1940. The lower level of a massive entrance block for this battery that led to the tunnel system below was completed, and was changed into the principal entrance, after work stopped on the tunnel system. A complex of munition rooms and supporting facilities encircled by a gallery was built in the tunnel system below the battery. Plans for positions with 50-mm guns in rotating turrets and special cloches for 105-mm howitzers were also projected, but none of these positions were built.
The first bunkers built in the Nischlitz-Obra Line were Type C-strength. The earliest, the two-level Hindenburg Stands, served as troop shelters and had a garage for a 37-mm anti-tank gun that was rolled out into an open position when needed. Some of these bunkers included a forward-facing machine gun position. The German firing positions on both the East and West Walls usually comprised a large armored 60-mm shield that formed most of the exposed facade and a rear entrance covered by a crenel for a light weapon. The small doors on these positions were similar to those of a ship and those of the B-Werke.
Late in the war, log machine gun bunkers with a concrete facade and open to the rear were created on the Pomeranian Line. Also in 1944 thousands of prefabricated one-man bunkers were deployed on the East Wall.
Other defenses employed on the OWB Line included rows of concrete dragon's teeth to stop tanks. Set at different heights they were usually poured in four rows and covered approximately 20 km of the Central Sector of the OWB Line in front of the werkgruppen.
According to a 1944 document, the hundred positions of the OWB Line required a garrison of about 4,300 fortress troops, including a regiment-size formation that would operate the vast tunnel system and service the fortifications. The subterranean complex would need up to 6,000 men, the Pomeranian Line, 7,500 fortress troops for its 4,000 positions, and the Oder Line another 7,500.
In East Prussia the strongest concrete positions were the older fortifications of Konigsberg. The terrain was the best defensive asset so that most positions set up in the area were of Types C and D. The Hohenstein Position relied on obstacles, water defenses and flooding devices for its defense, but also included a small number of concrete positions. It covered the border with Danzig, along the Vistula River. Christburg, a similar position, ran east of Elbing to Allenstein where it merged with the Ortelsburg Wald Position. Here, concrete bunkers covered the forest paths. Final
ly, the Lotzen and Hohenstein positions, much stronger than Christburg, relied mainly on the terrain for protection.
2. The West Wall
The older positions of the West Wall included light machine gun bunkers along the Upper Rhine and the Ettlinger Barrier, which became a switch-back position after the West Wall was built. The Ettlinger Barrier was built before the occupation of the Rhineland and included an anti-tank ditch and over fifty bunkers-mostly Type Cand the standard wire obstacles. Additional switch positions encircled the cities of Aachen and Saarbriicken.
The West Wall consisted in actuality, of three positions: the forward position, the main line, and the rear position. The forward position was 2 to 20 km deep, depending on the terrain. The main line, on the other hand, had a depth of 3 to 8 km. The rear position was a few kilometers behind the main line.
The West Wall is usually divided into three sectors: Northern, Central, and Southern. The Northern or Aachen Sector, which ran from the point where the Rhine entered the Netherlands to the cities of Aachen and Trier, was lightly defended. The Central Sector, sometimes identified as the two sectors of Trier and Pfalz, covered the area between Trier and Karlsruhe on the Rhine and concentrated its heaviest defenses in the Pfalz.11 The Southern or Oberrhein Sector covered the Upper Rhine and included Werkgruppe Istein and mostly light defenses covering the river crossings. By the time the war began the entire West Wall included 22,000 positions and an almost continuous anti-tank barrier.
Behind the three positions of the West Wall collectively known as the Army Position, lay the Luftwaffe Position, whose existence owed more to propaganda than actuality and was purported to bristle with anti-aircraft weapons capable of shielding Germany from aerial attacks.
Most of the bunkers built on the West Wall were standardized models that could mount a machine gun or a 37-mm anti-tank gun. A large number of troop shelters built for the Army came in sizes that could accommodate ten to twenty-six men as well as a machine gun position. Artillery observation positions for six men occupied key sites.