Features of an Atlantic Wall Bunker
The bunker was primarily an instrument of defence. For that purpose, most but not all Regelbauten included a number of standard features. The fortress engineer staff selected designs they needed and adapted them to local conditions. As a result, some bunkers in areas that were less vulnerable might lack some of the standard features designed to counter any assault. Shortage of construction materials also affected the design.
Whether the bunker was a weapons position, an Unterstand or a supporting position, the desired features included a protected entrance, and some bunkers had two. The simplest Regelbau bunkers had a 3cm-thick steel armoured door usually located inside a protected entrance hall with an open entranceway in the outside wall.67 The hallway connected at right angles to a small corridor with the door at the end. An embrasure for small arms covered the outside access to this corridor. A grating gate often closed off the open access to the entrance corridor. In some instances, where an entrance corridor was not present, the armoured door was on the outer wall. Often the armoured door was a heavy ‘Dutch Door’ that allowed the top half to open if the bottom section were blocked by rubble resulting from damage. The armoured doors included a double lever lock system and a rubber seal lined the edges to render them airtight and gas proof. A peephole with a cover allowed the occupants to inspect newcomers before letting them in. Except in the H-702, the armoured door opened into a gas lock for added protection. These entrance corridors included a decontamination niche, usually located at the opposite end from the entrance to the air lock.
Some bunkers included a close-combat room, a defensive position for a light machine-gun or small arms on a wall section that projected slightly beyond the outside wall so that its embrasure could cover the entire exposed wall and the entrance. One or two Tobruks at the rear of the bunker served as observation positions and provided additional protection for the entrance.
All bunkers, except the smallest, had some type of ventilation system. Armoured grilles covered air intakes on the outer walls. Larger bunkers included steel air ducts suspended along the ceilings and a ventilation system to which air filters could be introduced in the event of a gas attack. In multi-room bunkers and bunkers with gunrooms there were valves on the internal walls to control the internal air pressure, to provide gas protection and to reduce the effects of blasts on the human body. In the case of the latter, it proved not to be very effective. Most Regelbauten had additional heating vents, especially in the crew quarters. Although the larger, more complex bunkers usually had a form of central heating (even air-conditioning for cartridge rooms), most bunkers used a small standard type of heater, a WT80, in the crew areas; this type of heater had a roof vent that was designed to trap a grenade should the enemy get that close. Many of these features, including the anti-gas protection, were common in the permanent fortifications of most nations during this era.
Although the size of the bunkers varied widely, the height of rooms was established at 2.1–2.3 metres. The number of rooms was determined by the size and purpose of the bunker. Usually the interior walls were of concrete poured during the construction of the bunker, but in some cases they were made of brick. The interior doors, if armoured, were of thinner steel, but wooden doors were also common, especially if the door was for a brick wall. Normally, wood lined the walls and served as insulation because bunkers were cold and often damp. A standard concrete thickness was prescribed for all floors, but some were also covered with asphalt tiles to counter blast pressure effects from a direct hit on the bunker. These floor coverings enhanced the protection provided by the pressure valves between rooms.
Almost every type of Regelbauten had an emergency exit that consisted of a well on an exterior wall that led to the roof. This well had handrails for the troops to climb out, but it was filled with sand or gravel. The emergency exit was accessed through a small door on an inside wall. One or two small brick walls beyond this door had to be broken to allow the contents of the escape well to spill on to the floor of the bunker. The men inside would have to clear away the debris before they climbed out the escape well.
Larger bunkers normally included some type of communications equipment. For internal communication between rooms, the voice pipe was a standard feature. This fast and effective method was found in the many permanent fortifications of other nations as well. For external communication, the most common method was by runner, but telephones or even radios linked most large bunkers, especially artillery bunkers, to their command post. When a radio was present, the antenna was often located in the entrance hallway. The antenna extended and retracted through a tube in the ceiling. The command post usually had a telephone and radio link to higher headquarters. Telephone cables buried about 2 metres deep linked most of the bunkers in a strong-point to one another and to a higher headquarters.
Some combat bunkers and the larger Unterstände included a periscope for all-round surveillance. In the smaller bunkers the crews had to rely on the few embrasures to survey their surroundings. Most weapons embrasures had a stepped opening that narrowed towards the armoured embrasure. This feature, known as an anti-ricochet device, prevented enemy rounds from being funnelled into the embrasure. Some types of casemate with a large opening that allowed the gun a field of fire of up to 120° sometimes did not have or could not accommodate the stepped anti-ricochet device. Additional protection for large gun artillery bunkers often consisted of a stepped carapace extending beyond the roof. Some observation bunkers had cantilevered roofs to protect the observers.
Bunkers were usually covered with earth. Only their roof positions, walls with embrasures and entrances were exposed fully or partially. For additional protection many of the post-West Wall era bunkers had a stepped entranceway so that their floor level was below ground level for additional protection. In some locations it was not possible to cover the bunkers with earth because the terrain lacked relief. In some cases an artificial hill was raised around the bunker. In other cases the engineers employed various types of camouflage, even disguising the bunkers as civilian structures with a judicious coat of paint. Exposed walls received a camouflage paint job. Different types of texturing on the concrete surface were done in the mould when the concrete was poured. Bunkers that were not earth-covered and those with exposed walls had rounded corners to deflect enemy shells.
The interiors of the bunkers were rather spartan. Whenever possible there was electric lighting, but kerosene and/or acetylene lamps were the only light sources available in isolated areas. The men ate at wooden tables, slept on steel bunks and stored their personal effects and equipment in lockers. The soldiers cheered up their environments with wall paintings, but they were not allowed to conceal the painted wall signs that identified the rooms, the instructions for operating equipment, the warnings or the components of the bunker. Most interior rooms were painted white; it is believed that green and black were used on most of the metal components. A personnel shelter often had a nearby water source, unless it had its own well. While a large bunker normally had latrine facilities, most combat bunkers and Unterstände had none. Instead, the troops used a latrine bucket with a seat (a portable toilet) that was often located in the close-defence position, which gave the soldiers some privacy. Otherwise, the gas lock or the decontamination niche served as a latrine. The men probably used the latrine bucket only during combat. Most Wn would have some type of latrine facilities outside the bunkers for the troops. The StP was likely to have a latrine bunker.
The German Infantry Company and Platoon in Coastal Defence
The actual composition of German infantry units in coastal defence is a bit confusing. The organization of the company changed after 1940 when its standard composition was three rifle platoons and a heavy weapons platoon. In 1939 the platoon or zug (Schutzenzug or rifle platoon) consisted of a three-man light mortar section with a 50mm mortar and three thirteen-man rifle squads, each of which had a light machine-gun – an MG-34. Between 1941 and 1944 modifications took place, which reduced the rifle squad to ten men. A complete reorganization in 1943 introduced the ‘1944 Infantry Division’ with platoons of four rifle squads. The squad leader carried a submachine-gun. The standard rifle squad was referred to as gruppe (Schutzengruppe or rifle squad), which translates as ‘section’ instead of ‘squad’ and causes some confusion in written accounts. In 1944 many platoons numbered only three squads, which reduced their firepower to three light machine guns. The platoon’s mortar team initially had light 50mm mortars that were eventually replaced with 81mm mortars, and then eliminated in the ‘1944 Division’. The infantry company also included a machine-gun section with two heavy machine-gun teams. The heavy machine-guns were the same MG-34 or MG42s used in the rifle platoons, but with different mounts. In the battalion heavy weapons company, which had a heavy machine-gun platoon and two 81mm mortar platoons before 1944, one of the mortar platoons received 120mm mortars.
The change in the organization and appearance of the ‘1944 Infantry Division’ had little effect on the divisions assigned to coastal defence since most were static formations. The companies and platoons of these old divisions did not update to the new standards and they received older weapons and captured foreign models. Thus a rifle platoon assigned to beach defence might have more than the allotted number of machine-guns and could even have heavier weapons. Since their primary mission was to defend a Wn or StP, their internal organization was modified based on the position they held. The elements of these divisions that were not assigned to a Wn or StP and were held as reserve units conformed more closely to the standard table of organization for the pre-1944 division.