Normally the passive defences were covered by various machine-gun positions, including the MG Panzernest. This was developed in the second half of the war and proved invaluable when the German Army was on the retreat. Weighing just less than 3,200kg it could be transported and installed relatively easily and provided valuable protection for the two-man crew against enemy small-arms fire and shrapnel.
The nest was constructed from two steel prefabricated sections that were welded together. The top half contained the aperture for the gun, air vents and the rear entrance hatch, which was hinged at the base. This section was most vulnerable to enemy fire and was cast accordingly with armour around the aperture 13cm thick and 5cm around the sides and the roof. The base of the unit, which was completely below ground, was about 12.5mm thick.
The frontal aperture was divided into two parts: the lower part accommodated the gun barrel and the upper part was for sighting. Two periscopes in the roof provided further observation. When not in use the aperture could be covered with a shield operated from within the shelter. The relatively small aperture meant that the machine gun had a limited field of fire of approximately 60 degrees. Because of this and because the nest could not be rotated they tended to be used for flanking fire with other positions providing mutual support.
A simple foot-operated ventilation system was provided that used holes at the side of the turret. These also acted as the mounting for an axle. With the nest upside down wheels could be fitted on either side. A limber was attached to the machine-gun embrasure and two further wheels were located in front. This was then hooked up to a tractor and the whole could then be towed.
Machine guns were also fitted in old tank turrets mounted on concrete bunkers. These were built to a standard design. Directly below the turret was the fighting compartment. This was fitted with wooden duckboards, which not only improved the crew's footing but also served as a repository for spent machine-gun cases. Any water that entered the fighting compartment would also collect here before being channelled through a drain to the lower level, where the floor was angled at 2 degrees to direct water out of the shelter to the soakaway at the entrance. Access to the fighting compartment was via a flight of steps from the anteroom inside the entrance, which in turn was linked to a revetted trench at the side. This room also housed the hand-operated ventilation system.
Turrets were taken from a number of obsolete German tanks. These included a number of modified PzKpfw I turrets. The original mantlet was removed and replaced with a 20mm-thick plate with openings for the machine gun and the sight. The two vision slits in the turret side were dispensed with and were covered by 20mm steel plates which were welded over the openings as ventilation ports. This meant they were much better suited for their new role. A number of PzKpfw II turrets were also used and a similar number of Czech PzKpfw 38(t)s were also made available for use in the Gothic Line.
There were also plans to use large numbers of Italian tank turrets that had fallen into German hands following their occupation of the country. These turrets were to be mounted on specially designed concrete bunkers (although a wooden design was also later developed). There were plans to install 100 P40 turrets and 100 M42 turrets in the Voralpenstellung, but it is unclear as to whether this work was completed. A number of other Italian tanks were simply dug in and used as improvised strongpoints. P40 tanks were used in this way in the Gustav Line and at Anzio when work to replace its unreliable diesel engine proved problematical; a number of L3 tankettes were used in a similar fashion.
In addition to the tank turrets, ten specially designed armoured revolving hoods (F Pz DT 4007) were installed capable of mounting either an MG34 or MG42. These were constructed from steel plate, but were sufficiently light to be man portable. They could be mounted on either a prepared concrete or wooden shelter or, if necessary, simply on firm ground.
These, and the other tank turrets, were primarily for use against infantry, but a large number of Panther tank turrets were also used as improvised fixed fortifications. They retained their powerful 75mm gun and were often the main anti-tank weapon in the defensive line. The turrets were either taken from production models (Ausf. D and A) or were specially designed for the role. The Ostwallturm (or Ostbefestigung) as it was known, differed from the standard turret in a number of ways. The cupola was removed and was replaced by a simplified hatch with a rotating periscope, and the roof armour was also increased in thickness because of the greater threat to the turret from artillery fire. The turrets were mounted on either concrete bunkers or, more often, on steel shelters. The Organization Todt had developed a series of prefabricated steel shelters and one of these was adapted to mount a Panther turret. It was constructed in two parts from electrically welded steel plates. The upper box essentially formed the fighting compartment. It held the ammunition for the main weapon and incorporated the turret ball-race onto which the turret was mounted. The lower box was divided into three compartments. The largest formed the living accommodation and was fitted with fold-down bunk beds and a stove. A further room acted as either a general store or as home to various pieces of equipment that provided power for the turret and shelter. And finally, there was a small anteroom fitted with a steel ladder that linked the upper and lower boxes and was also where the main entrance was located. A revetted trench, covered near the entrance, led away from the shelter and linked it to the main trench system at the rear.
A large number of the original steel shelters developed by the Organization Todt were also installed in the various lines to provide protection for troops against enemy artillery and air attack. Other shelters were constructed from timber with soil and rocks heaped on top for added strength. These different shelters were often linked to fighting positions mounting a variety of weapons including machine guns, mortars, Nebelwerfer, artillery pieces and anti-tank guns.
Later in the war there were plans to install tank guns in open pits as improvised anti-tank positions. The powerful 8.8cm guns taken from Jagdpanther tanks were to be fitted to pivot mounts and 5cm 39/1 L60 guns taken from PzKpfw IIIs were to be mounted on makeshift carriages. At the other extreme the Germans built a number of permanent positions. Around the Futa Pass, for example, a number of concrete bunkers to mount anti-tank guns were constructed. On the Adriatic coast near Rimini large coastal emplacements, not dissimilar to those found in the Atlantic Wall, were built. These mounted 15cm guns that had originally been designed for use on ships. Dragon's teeth, or Hockerhindernisse, which had first been employed by the Germans in the West Wall, were also used extensively around the coast in attempt to deter a further Allied amphibious assault. These were essentially reinforced concrete pyramids poured in rows and designed to either stop an enemy tank completely or to expose the thinner armour of the underside of the tank to the defenders' anti-tank guns.