The 5cm Granatwerfer 36

Diagram of German M19 5cm automatic mortar as sited in the Channel Islands and at points on the Atlantic Wall.

From the very start of the war, the German Army placed a great deal of store in mortars of various calibres and deployed them to every theatre of war, from North Africa to the Balkans and north-west Europe. The lightest calibre mortar produced expressly for the German Army was the 5cm leichte Granatwerfer 36 (leGrW36), which had a weight in action of 30.9lbs, considerably heavier than anything used by the Allied armies. Despite this it fired a HE bomb of just under 2lbs in weight, which was less than the weight of the bombs fired by the British 2in mortar or the Japanese Model Type 98 of comparable calibre. At the start of the war, the leGrW36 was standard equipment with every platoon within an infantry regiment of the German Army and required three men for its operation. It was used at company level to provide the company commander with immediate fire support to platoons and sections. At the time of Operation Barbarossa, the German invasion of the Soviet Union in June 1941, there were eighty-four of these mortars in service with each division. The crew between them carried forty-five rounds of ammunition ready to use, and with a firing rate of forty rounds per minute this gave them just over one minute in action. However, these supplies would not have been expended so quickly and targets would have been engaged selectively in order to conserve ammunition and provide the maximum fire support to those areas where it was most needed. The mortar had a barrel length of 19.3in and could fire at angles of elevation between 45 and 90 degrees, with a maximum range of 550 yards with a HE bomb.

The ammunition for the 5cm mortar was termed Werfergranate 36 and was made with a cast-steel casing. It was fitted with the Werfergranatzunder 38 fuse, which also had ‘graze’ action. For safety purposes the fuse only became armed some 60 yards out from the muzzle after firing. The graze action on the fuse meant that if the bomb were to descend through trees, there was a high possibility that it would brush against branches which would set off the detonation train of the fuse to produce an air burst action. This type of fuse was fairly common at the time and other armies also had versions incorporating similar actions for the same effect. The ammunition for the leGrW36 was carried in pressed steel containers, each holding ten rounds ready to use.

It has been argued that the 5cm mortar of the German Army was actually over-engineered and fabricated from the best quality metals. This is supported by the comments made in a report following an examination made on captured examples which were also test fired in 1941, by the British Army which stated that is was ‘well-constructed and easy to operate, but the degree of accuracy is unnecessarily high’. The barrel was attached to the baseplate by means of a locking pin, which allowed it to be moved through its arc of firing independently of the baseplate’s angle to the ground. The first examples of the mortar had been issued during the re-armament programme in the mid-1930s and these were fitted with a collimating sight. It was later decided to dispense with this, as on the British 2in mortar. Like that weapon, it was left to the experience of the firer to judge the angle of the barrel when in use. The leGrW36 could be broken down into two parts for carrying by the crew. This was achieved by removing the locking pin and disconnecting the elevating mechanism so that the barrel and baseplate became two separate loads. The 5cm mortar was used by Gebirgsjäger (Mountain Troops) during operations where they were engaged in anti-partisan actions among the peaks in regions such as Crete, Greece and Yugoslavia. The Germans nicknamed it the Zigeuner-Artillerie (Gypsy Artillery) because the weapon was quick and easy to move from one location to another on the battlefield. Despite its usefulness in such terrain, the Germans came to realise the weapons were too heavy, too expensive and too complex for the limited downrange effect they provided and eventually decided to follow the move of the Soviet Red Army concerning the use of 5cm mortars, and by 1943 the GrW34 had been withdrawn from service. Production of ammunition was halted but it remained in service with some of the more remote garrisons such as the Channel Islands, where stocks of ammunition were unused, except for a few rounds expended for training purposes.

The Gebirgsjager were specialist infantry with a typical division having 14,131 troops of all ranks, 3,506 mules and horses along with more than 550 bicycles for the ‘Cyclist Battalion’ within its organisational structure. The bicycles were a cheap and efficient method of moving a battalion over distances without having to rely on motor transport. Some of the bicycles were fitted with brackets at various points, such as the crossbar and handlebars, to permit heavy weapons including machine guns and the 5cm mortar to be carried. Ammunition could be carried in panniers on the rear or in special saddlebags. The bicycle battalion of the Gebirgasjager had six 5cm mortars and three 8cm mortars, while the two infantry regiments combined had a total of fifty-four GrW36 and thirty-six GrW34.

The Germans occupied the British Channel Islands in July 1940 after the surrender of France, and the islands would remain in German hands for almost five years. During that time the three main islands in the archipelago, Jersey, Guernsey and Alderney, were fortified out of all proportion to their actual strategic value. The garrison spread across the islands increased to an eventual strength of around 46,000, including some 15,000 forced labourers who were taken to the islands to build the defences which encircled each of them. Although there were elements of the Luftwaffe and Kriegsmarine, which provided anti-aircraft batteries and coastal artillery units, the main bulk of the force was provided by the infantry. Initially this had been 216th Division but this was replaced by 319th Division in May 1941. The infantry deployed all the usual standard weapons such as machine guns and flamethrowers, but they also prepared defensive emplacements for mortars, including the 5cm GrW36 and the heavier 8.1cm GrW34, of which there were about thirty-nine and forty-three respectively deployed to Jersey. One of these positions was located at La Crete Fort, built on a promontory between the harbour at Bonne Nuit Bay and Giffard Bay on Jersey’s north coast. The site had been used as a defensive point since the seventeenth century and updated in the nineteenth century. The buildings were modified by the Germans to accept mortars and machine guns, and included a guardhouse that could be used by the garrison of twenty troops. The site overlooked the sea on three sides and from there the mortars could be traversed in all directions with unimpeded views to engage any would-be assault force. Another mortar-firing position was built at St Aubin’s Fort, which dates from the sixteenth century and lies at the western end of St Aubin’s Bay on the south coast of the island. The special emplacement had a concrete platform from which the crew could traverse the mortar to engage targets at all angles of approach.

Apart from the two standard types of service mortars, the occupying forces also bolstered the defences with captured weapons which included a range of French and Soviet mortars. On Jersey this included at least twenty-eight French 50mm mortars which were given the German Army service nomenclature of 5cm GrW210(f) and are understood to have been taken from the defences of the Maginot Line. Soviet weapons included eleven 52-PM 37 mortars known in German service as 5.2cm GrW205(r) and a few 82-PM 36 which the Germans referred to as the 8.2cm GrW274(r). These began arriving on the island in late 1941 and 1942. One of the units recorded as using these weapons on Jersey was the 4th Battalion, 582nd Infantry Regiment, which included the 643th Battalion, the Russiskaya Osvoboditelnaya Armiya (Russian Liberation Army). Soviet troops volunteering to serve with German units were posted at low key defensive positions along the Atlantic Wall in those areas where it was considered unlikely that an Allied invasion would come. One of these areas was the Channel Islands and, as such, most of the Soviet troops sent here would have been trained in the use of Soviet weaponry.

The islands had been under occupation for more than fifteen months when Hitler issued a directive on 20 October 1941 which ordered that permanent defences be prepared on each of the islands. Directive No. 441760/41 for the ‘Fortification and Defence of the British Channel Islands’ was marked ‘secret’ and contained instructions that: ‘Defence measures on the Channel Islands must guarantee that a British attack will be repulsed before reaching the islands irrespective of whether the attacks are by air, by sea, or a combination of both. It must be taken into account that the enemy may use bad weather for a surprise attack. Immediate steps to strengthen the defence measures have already been ordered.’ The campaign into the Soviet Union was only three months old and going very much in Germany’s favour, and one would have thought this would be Hitler’s main priority, but in this directive we see that he is concerning himself with a minor aspect in the overall conduct of the war. This concern has led historians to conclude that he became obsessed with holding on to these British possessions at whatever cost. The war was also going in favour of Rommel’s Afrika Korps in North Africa, where the British and Commonwealth forces had been pushed back to Egypt. Yet, here he was devoting time to draft directives concerning occupied territories of little importance other than for propaganda.

The islands had already been subjected to several raids by British commando units, conducted mainly against Guernsey, with the aim of establishing the strength of the garrison. By interrogating prisoners, the British were able to build up a picture of what was happening by 1941 and gauge morale of both the civilian population and the military government. These raids achieved more through their irritating effect by keeping the Germans on a state of alert rather than any genuine military success. However, they did create a reason in Hitler’s mind to continue defending the islands. His October 1941 directive continued by stating: ‘For the permanent fortification of the Channel Islands, which must be pressed forward energetically in order to create an impregnable fortress, I therefore order the following …’ The document continues by outlining the responsibilities of the Luftwaffe and Kriegsmarine on the islands, but emphasis is given in particular to the role and duties of the army. One of the paragraphs of the directive states that: ‘For the Army the most important constructions are close-meshed flanking installations spacious enough to contain guns with a calibre sufficient to penetrate armour 100mm thick, and for defence against tanks which may be landed from barges.’ Recommendations for storage of ammunition are all outlined and how such construction work, in keeping with installations along the Atlantic Wall, would be built using ‘foreign workers, especially Russians, Spaniards, but also Frenchmen’. These were slave labourers under the direction of Organisation Todt. The Atlantic Wall defences they built would eventually stretch for over 1,600 miles, from Norway to the Spanish border. It absorbed 18.6 million cubic yards of concrete and almost 1.2 million tons of steel to create thousands of emplacements, from the smallest to the largest, which housed long-range guns which could fire shells more than 30 miles across the English Channel to bombard the town and harbour facilities at Dover in Kent.

There were many different types of installations built, into which were mounted weapons of all types from machine guns to massive pieces of artillery capable of firing shells many miles. One design mounted automatic mortars in armoured cupolas, an idea which had occurred to military planners as early as 1934, and the Dusseldorf-based company of Rheinmettall-Borsig was awarded a contract to develop such a design. At the time the French Maginot Line was at an advanced stage of building and some of the defences incorporated mortars mounted in steel cupolas, and this idea may have inspired the German planners. The French opted to equip their cupolas with either 50mm or 81mm mortars, while the Germans decided on just mortars of 5cm calibre based on the GrW36 weapon, which, by coincidence, was also manufactured by Rheinmettall-Borsig. One theory put forward as to why the lighter calibre was chosen is because it would not have placed too much of a strain on production and supply in the way a larger calibre would have. Armament factories in Germany could have coped with extra production and certainly those armaments factories in occupied countries, such as France, could have added to the supply. The truth is probably due to size and weight of the ammunition, which could be handled by infantrymen instead of requiring specialist handling equipment. The M19 automatic mortar fired standard bombs from a metal tray-like magazine which was pre-loaded with six bombs. The 5cm HE bomb weighed 1lb 15.5oz, and together with the weight of the complete magazine each would be just over 12lbs. If this had been done with the GrW34 8cm HE bombs, each of which weighed 7lbs 8oz, the weight would have been over 45lbs and the magazine tray would have been much larger and heavier. Indeed, size was a major contributing factor and to put it in simple terms of logistics, more of the smaller 5cm bombs could be stored inside the bunker than the larger 8cm bombs.

Rheinmettall-Borsig produced ten studies into developing a complete system for an automatic mortar before making a final choice which would become the M19 5cm Maschinengranatwerfer. The operational role of the system was to provide firepower to cover areas of ‘dead ground’ which could not otherwise be observed. This was usually an area on the coastline with steep cliffs, but that was not exclusive. Apart from firing the 5cm calibre mortar bomb, the weapon used in the M19 system was completely different to the standard GrW36 used by the infantry. Using standard dismountable mortars in such a defensive role would have only been a short-term solution and they would have needed to be removed periodically for service. Emplacing a weapon mounted in a specially-produced turret or cupola would provide a permanent position, ready to provide all-round 360-degree traverse and able to come into action at a moment’s notice to cover all points of approach to the defensive site. Initially, these automatic mortars were intended for installation in the Westwall and the Eastwall, a defensive system also known as the Oder-Warthe-Bogen Line. This was built between 1938 and 1940 on the border between Germany and Poland. It covered a length of around 20 miles and included around 100 main defensive emplacements. After the successful campaigns in 1939 and 1940, it was decided not to install the weapons in these locations and instead they would be sited at intervals along the Atlantic Wall, which included several being built on the Channel Islands of Jersey, Guernsey and Alderney.

The M19 installation on the island of Jersey was built at Corbière Point at the western end of the island, which was turned into a strongpoint to defend the headland. From here its high rate of fire could be useful in engaging targets at close quarters and overlap with the firepower of machine guns and two 10.5cm field guns also sited at the point. The neighbouring island of Guernsey had four M19 automatic mortar installations, including one located at Hommet, overlooking Vazon Bay on the north-west coast, where its firepower could be integrated with that of machine guns, at least three pieces of artillery with 10.5cm calibre and a 4.7cm gun of Czechoslovakian origin. On Alderney there were two M19 strongpoints with other similar installations built along the much-vaunted Atlantic Wall, including three in Norway, nine in Holland, one in Belgium, twenty-two along the French coast and twenty along the Danish coastline, with four more planned but not built. For such a small weapon it absorbed a huge amount of resources in manpower to build the emplacement, with tons of concrete and steel in its construction. The sites of the M19 automatic mortars were out of all proportion compared to those built for heavier weaponry in defensive positions. The M19 mortar could fire HE bombs at a rate of between sixty and 120 rounds per minute, although the higher rate of fire was rarely used in order to minimise stresses and prevent the weapon from overheating. The crew could engage targets at ranges between 54 and 820 yards, which was closer than artillery could achieve, and together with support fire from other weapons such as machine gun, any infantry attack would have been met with fierce opposition. Indeed, one M19 position on the Eastwall held out for forty-eight hours when attacked by troops of the Red Army in early 1945.

The M19 weapons were mounted in steel cupolas which had an internal diameter of 6ft 6in to accommodate the three-man crew during firing. Initially, there were two main designs of cupola, the 34P8 and the 49P8, but it was a third type, the 424PO1, which became the most widely used with armour protection 250mm thick. The cupolas were mounted on specially-prepared bunkers designated ‘135’, with concrete protection up to 11.5ft thick, and the ‘633’, which was the most common design and the type used in the Channel Islands. The M19 bunkers were divided into several rooms including the firing room and had accommodation for up to sixteen men. Each bunker had its own independent generator to provide power to traverse the firing platform and cupola, but in the event of a power failure the weapon and cupola could be elevated and traversed by means of hand-operated wheels. The ammunition storage room had racks for thirty-four trays, each pre-loaded with six bombs, giving a total of 204 bombs ready to fire. Ammunition boxes containing ten bombs each to reload the spent trays were stored in this room, and it was the task of the crew members to reload these. In total an M19 bunker could have ammunition reserves of up to 3,944 bombs stored in readiness for use. These bunkers were equipped with field telephones and optical sight units such as the Panzer-Rundblick-Zielfernrohr, an armoured periscope with a magnification of × 5. Because it was an indirect fire weapon, the M19 had to be directed on to its targets and integrate its fire by overlapping with neighbouring weaponry.

The firing platform on which the mortar was mounted could be elevated when firing and lowered when not in use. The loaded ammunition trays were fed up to the platform by means of an elevator where the loader removed them and fed the trays into the left-hand side of the weapon’s breech. As it fired, a mechanism moved the tray along to feed the next bomb into the weapon, and the process continued until the empty tray emerged on the right-hand side of the weapon, where a handler removed them and placed them in the descending elevator section. These were removed by another member of the crew and taken to the ammunition room, where they were reloaded ready for reuse. The M19 could fire the standard types of Wurfgranate 36 bombs, which these were fitted with colour-coded graduated propellant charges to be used according to the range required. The red charge was for use at ranges from 22 to 220 yards and the green charge was for ranges from 220 to 680 yards. There were training bombs which had no filling and could not be fired, which were really for familiarising crews with handling procedures of the weapon. There were two training systems developed to teach crews how to operate the M19; the first was the Sonderanhangar 101 mounted on a trailer and the other was the Ubungsturm, which replicated the complete cupola layout

Preparing the weapon to fire, the operator lifted the barrel clear of the breech by means of a cam and lever mechanism which allowed a bomb on the loading tray to be aligned with the chamber. As the barrel was lowered over the bomb, the firing pin in the breech was activated to initiate the propellant charge. The recoil forces on firing unlocked the barrel a fraction of a second later and the cam mechanism lifted the barrel clear of the breech, and another bomb was loaded ready to fire as the tray was fed through.

As the Allied campaign to liberate Europe continued in the second half of 1944, the Germans had to rethink their defensive strategy. From September 1944 they renewed construction work on the Westwall to improve defences and began to install M19 systems at certain locations. The actual numbers of M19 systems built and turrets installed varies according to sources. Some, for example, state that perhaps seventy-three such installations were built in the Atlantic Wall. These did not cause the Allies any unnecessary problems and those along the Westwall were largely ineffective, while those in the Channel Islands never fired a shot in anger. In summary, it was indeed a great deal of effort for such a small weapon which did not play a decisive role in stopping or even slowing down the Allied advance.