WORLD WAR II GERMAN SUPER- HEAVY SIEGE GUNS MARC ROMANYCH ILLUSTRATED BY ADAM TOOBY AND AND MARTIN RUPP ANDREA RICCIARDI DI GAUDESI NEW VANGUARD 280 WORLD WAR II GERMAN SUPER-HEAVY SIEGE GUNS MARC ROMANYCH ILLUSTRATED BY ADAM TOOBY AND AND MARTIN RUPP ANDREA RICCIARDI DI GAUDESI CONTENTS INTRODUCTION 4 THE RETURN OF FORTRESS EUROPE 4 DESIGN AND DEVELOPMENT 6 • 60cm and 54cm Karl-Gerät • 80cm Railway Gun Gustav-Gerät • 35.5cm Haubitze M1 • World War I-Era Guns • Skoda Siege Guns • Ammunition OPERATIONAL HISTORY 28 • Siege Gun Units • 1939 – Poland • 1940 – Campaign in the West • 1941 – Eastern Front • 1942 – Sevastopol and Leningrad • 1943–45 – Decline of the Siege Guns CONCLUSION 46 BIBLIOGRAPHY 47 INDEX 48 WORLD WAR II GERMAN SUPER-HEAVY SIEGE GUNS INTRODUCTION As the Third Reich prepared for war, it faced the same problem that had confronted its predecessor, Imperial Germany, nearly 20 years earlier on the eve of World War I. Germany was encircled by strong fortifications and needed artillery to destroy them. However, unlike 1914, when the Imperial German Army had an arsenal of large-calibre siege guns, in the mid- 1930s, the Third Reich had none. As it rearmed, the army ordered artillery manufacturers Krupp and Rheinmetall-Borsig to build super-heavy siege guns capable of destroying France’s Maginot Line, the strongest fortification in Europe. These new super-heavy artillery pieces were much larger and more powerful than their World War I counterparts, but were also far more difficult to manufacture and, as war drew near, not one of the guns had been completed. As a stop-gap, the army equipped itself with World War I-vintage siege guns, primarily Skoda-made artillery taken from Czechoslovakia in Germany manufactured several 1938–39, and then went to war. super-heavy siege guns for the During World War II, the German Army employed siege guns during specific purpose of destroying modern reinforced concrete campaigns in Poland, Belgium, France and the Soviet Union. At its zenith, fortifications such as France’s during the siege of Sevastopol in the Crimea in 1942, Germany’s siege Maginot Line. Seen here is the artillery totalled 30 guns, including the massive self-propelled 60cm Karl first prototype self-propelled mortars and the 80cm Dora railway gun. By 1943, as Germany was forced 60cm Karl-Gerät mortar. (M. Romanych) onto the defensive, the need for siege artillery rapidly diminished and the guns were either retired from service or employed as heavy artillery in support of the armies on the Eastern and Western Fronts. THE RETURN OF FORTRESS EUROPE Before World War I, the European armies emphasized permanent fortifications to defend their borders and cities. However, the success of German 42cm and Austrian 30.5cm 4 Each Karl mortar had two tracked ammunition carriers for delivering rounds, propellant charges and cartridge cases to the mortar. The carrier could carry four rounds and had a crane for transferring the rounds from the carrier to the mortar. (G. Heuer) siege guns against Belgian, French and Russian forts in the first two years of the Great War rendered large permanent fortifications obsolete, and armies on both sides abandoned such fortifications for trench systems reinforced with small concrete casemates and shelters. By the end of the war, both permanent fortifications and siege artillery were out of favour with the warring armies. After the war, Germany’s siege guns were either confiscated by the Allies or destroyed in accordance with the armistice and Versailles Treaty. Only one siege gun survived, a 42cm Gamma howitzer that was dismantled and hidden by Krupp. Similarly, most siege artillery of Germany’s wartime ally, Austro-Hungary, was seized by Yugoslavia, Hungary, Czechoslovakia, Italy and Romania. The Versailles Treaty not only destroyed Germany’s siege artillery, but also sought to prevent the design and manufacture of new pieces. To circumvent the treaty’s restrictions, the Reichswehr (Germany’s armed forces from 1919 until 1935) surreptitiously established manufacturing arrangements between its two artillery manufacturers – Krupp and Rheinmetall – and the firms of Bofors in Sweden and Waffenfabrik Solothurn in Switzerland. However, the design of siege guns was ignored in favour of smaller, more mobile pieces, and the manufacture of new super-heavy guns had to wait until after the Third Reich renounced the Versailles Treaty in 1935 and expanded its military rearmament programme. Suspicious that Germany was secretly rearming, adjacent countries began to construct permanent fortification systems in the late 1920s. First, France began building the Maginot Line in Alsace and Lorraine, then Belgium rebuilt its defences at Liège and Namur, and the Netherlands constructed a series of blockhouse lines along its border with Germany. Inspired by France’s Maginot Line, Czechoslovakia heavily fortified its borders with Germany and Austria, and Poland built fortified positions to defend itself from a German invasion. Even neutral Switzerland erected border defences 5 to deter German aggression. Central Europe was a fortress once again, much as it had been on the eve of World War I, and Germany, now encircled by fortifications, decided to equip its army with siege artillery. DESIGN AND DEVELOPMENT Although the German Army did not officially designate any artillery pieces as siege guns, it did build super-heavy artillery pieces for siege operations. For the purposes of this book, German World War II siege guns are defined as super-heavy mortars and howitzers, 28cm or larger in calibre, designed or used to destroy fortified targets. Additionally, German Army designations of artillery pieces as either Mörser (mortar) or Haubitze (howitzer) should not be taken strictly because the terms overlapped and were different in World Wars I and II. Before and during World War II, artillery manufacturers Krupp and Rheinmetall built three different types of super-heavy siege guns for the German Army: a 60cm self-propelled mortar, an 80cm super-heavy railway gun and a mobile 35.5cm long-range howitzer. Designing and manufacturing such large and complex artillery pieces was a lengthy process and the military’s need for siege artillery grew more immediate as the prospect of war drew nearer. To solve the problem, the Army High Command had Krupp reassemble the vintage 42cm Gamma howitzer hidden at its factory, and then, when the opportunity presented itself in 1938 and 1939, it acquired a large number of World War I-era Skoda siege guns from the Czechoslovakian Army. SELF-PROPELLED SIEGE GUNS A Development of a self-propelled siege gun began in 1936 after artillery manufacturer Rheinmetall created a concept for a ground-mounted 80cm mortar with a 1,000m range. The proposed weapon lacked mobility and range, so Rheinmetall reworked the concept into a smaller 60cm mortar with a range of 3,000m that could be disassembled into several components transported on wheeled vehicles. However, the mobility of the weapon was still below expectations, so Rheinmetall redesigned the concept again. This design, which eventually became the 60cm ‘Gerät 040’ or ‘Karl-Gerät’, evolved several times until approved for production in March 1938. 1. Muzzle-Loading 60cm Mortar (Conceptual Design): Rheinmetall’s first design for a self- propelled siege gun featured a muzzle-loading mortar with a hand-operated crane for loading ammunition into the mortar’s muzzle. To fire, the mortar’s barrel would have to be super-elevated and then flipped over to face in the opposite direction. Key features of this design included an internal dual recoil system and a spade mounted on the rear of the tracked carrier. This design never progressed beyond a concept. 2. Breech-Loading 60cm Mortar (Conceptual Design): Rheinmetall’s second design was a breech-loading mortar. It too was mounted on a tracked carrier with a crane to load ammunition, but the gun now faced the direction of fire. The mortar had a more robust recoil mechanism mounted above the barrel, but a spade was still needed to anchor the carrier in place. This design also remained a concept and never left the drawing board. 3. 60cm Karl-Gerät (Production Model): The final design was significantly different from the previous concepts. The mortar faced the rear of the carrier so that the weapon could be driven quickly out of its firing position. The previous designs’ recoil spade was replaced by a carriage slide inside the carrier’s hull. In all, six Karl mortars were built. Modifications to the vehicle engine, drive train and suspension were continually made during the production cycle of the mortars, so none of the six weapons was identical. Particularly notable was the suspension system. The first two Karl mortars had eight road rubber wheels per side, while later weapons (like that shown in this illustration) had 11 steel road wheels. 6 1 2 3 60cm and 54cm Karl-Gerät As the first fortifications of France’s Maginot Line neared completion, the German Army began seeking artillery to bombard them. The army, knowing that the Maginot fortifications were built to withstand a direct hit from a 42cm projectile, the largest calibre used by Germany in World War I, queried both Krupp and Rheinmetall about what calibre weapon was needed to destroy the Maginot Line. The enquiry initiated two different super-heavy artillery development programmes. The first siege gun considered by the German Army was a super-heavy self-propelled mortar. Rheinmetall began working the concept in 1934 and initially proposed an 80cm ground-mounted mortar. However, concerns about the weapon’s mobility and range resulted in a series of redesigns until, in March 1938, the army approved Rheinmetall’s design for a self-propelled 60cm mortar and ordered seven of the weapons. Although manufacture of the first piece proceeded quickly, it was not ready in time for use against the Maginot Line in May 1940. Yet, even with the capture of the Maginot Line, construction of the 60cm mortar continued, with six guns completed and delivered to the amy from February to July 1941. The seventh piece, which was re-engineered with a smaller 54cm calibre barrel, was not finished until 1944. Confusingly, the 60cm self-propelled mortar had several names and designations during its life. While in testing, the first weapon was given the cover name ‘Gerät 040’ and, as each subsequent piece was built, it was numbered in order of production by a roman numeral, I–VII. In 1941, the Gerät 040’s official designation was changed to ‘Gerät-Karl’ and then again in 1942 to ‘Karl-Gerät’. After being fielded, artillery units nicknamed the guns: I – Adam; II – Eva; III – Odin; IV – Thor; V – Loki; VI – Ziu; VII (unknown). The Gerät 040 was a massive weapon, measuring 3m tall, 11m long and 3m wide, and weighing an astounding 123 metric tonnes. Its two primary components were the gun and the tracked carrier. The gun was a conventional, fixed-mount mortar similar in design to a coastal or fortress artillery barbette piece. The gun tube was 60cm (23.8in) calibre and short (about 5m). To absorb the force generated when firing, the Gerät 040 had a dual recoil system. One mechanism was built into the gun cradle to brake the barrel’s recoil and return it to firing position, and a second was mounted on The primary means of transporting the Karl mortar was by rail. Despite its great bulk and size, the railway transporter with mortar could pass over, and through, existing bridges and tunnels. (M. Romanych) 8 To transport the Karl mortar by road, it was disassembled into four components and loaded onto special trailers. The largest component, the tracked carrier, was transported on a heavy- duty wheeled trailer pulled by artillery tractors. (NARA) the bottom of the gun carriage to allow the gun to slide backwards inside the carrier’s hull. To relieve pressure on the suspension and increase stability, the hull was lowered onto the ground when firing. The mortar was fired at elevations between 55 and 70 degrees and had limited traverse – four degrees – which was enough to adjust fire on a specific target. For larger changes in direction of fire, the tracked carrier was shifted by turning it on its tracks. To facilitate loading of the rounds and propellant, a loading tray with a hand- cranked rammer was attached to the gun carriage. The carrier was a large steel box hull partitioned into three sections. The front section contained the engine, power train and compartments for the driver and assistant driver. The first four Gerät 040s were built with 580hp gasoline engines, but because of reliability problems, an 800hp diesel was used in subsequent vehicles and eventually replaced by gasoline engines. Depending on the type of engine, the Gerät 040’s top speed was 10km/h. The centre section was a large open compartment for the gun. The rear section contained the batteries for the engine and the gear system for lowering the carrier to the ground. The bottom of the carrier had a grid of steel grips that held the carrier in place when firing. The Gerät 040 was designed to be self-propelled for only a few kilometres, typically from its assembly area to the firing position. For long-distance travel, the weapon was moved by rail via specially built rail transporter that, when loaded with the oversized Gerät 040, could fit through existing bridges and tunnels. For shorter distances, the Gerät 040 was disassembled and loaded onto trailers towed by artillery tractors. Two types of projectiles were made for the Gerät 040. The first projectile was a schwere Betongranate (heavy anti-concrete projectile). The projectile was 2.5m long and weighed 2,170kg. The Gerät 040’s maximum range when firing the heavy projectile was 4,300m. The projectile could penetrate up to 2.5m of reinforced concrete. In 1942, to extend the range of the Gerät 040, a 1,700kg leichte Betongranate (light anti-concrete projectile) was developed. The lighter projectile could be fired to 6,640m. Firing tables estimated that only 50 per cent of rounds were likely to strike within a 19m x 3m target 9 area, which was surprising low, considering that the mortar was designed to fire only a few rounds on its target. To facilitate firing operations, a tracked ammunition carrier was built for the Gerät 040 by modifying a Mark IV tank chassis. The carrier could hold four projectiles with propellant charges and cartridge cases. An electric-driven crane was mounted on the carrier’s hull for transferring the projectiles, propellant and cartridge cases to the Gerät 040. The Gerät 040 had a crew of 21 soldiers. After offloading from its rail transporter or road trailers, the Gerät 040 was assembled and driven under its own power to its firing position. An ideal position was located behind a hill or woods, to avoid enemy observation. Before the Gerät 040 arrived, the firing position was cleared of brush and other material and, if necessary, the ground levelled. Upon arrival at the firing site, the Gerät 040 was backed into position with its gun facing the in the general direction of the target and then laid into its azimuth of fire. The carrier was then lowered to the ground, the gun carriage unlocked and crew platforms were put in place. A projectile and cartridge case were transferred from the ammunition carrier to the mortar’s loading tray and pushed into the breech using hand- cranked rammer. The barrel was then set to proper azimuth and elevation. Before firing, the gun crew and ammunition carrier moved away from the weapon. The process was repeated until all allocated rounds were fired or the Gerät 040 had to move. A crew of a Gerät 040 could thus achieve a rate of fire of one round every ten minutes. The Gerät 040’s short range was a concern throughout its development and operational life, and in 1941 Rheinmetall was ordered to design a smaller-calibre (54cm) and longer-barrelled gun for the Gerät 040 with a range of 10,000m. The new weapon – designated the Gerät 041 – was completed in the summer of 1944. Six additional barrels were manufactured to eventually replace worn-out 60cm barrels on the Gerät 040s. To convert a Gerät 040 to a 041 required a few minor changes to the gun cradle, but MOVING THE 60CM KARL MORTAR B The Karl mortar was designed to self-propel over short distances. For long distance travel, it was transported by rail using specially built railway wagons. A pair of massive five-axle wagons with large pedestal-mounted trusses were used to lift and suspend the entire gun and carrier between the two wagons. The trusses were attached to lift points on the carrier, and four powerful hydraulic jacks raised the trusses and mortar into the suspended travel position, creating a single unit for transport. When the railway wagons were moved without the mortar, the trusses were coupled together, and the wagons were connected with tow bars. The rest of the unit’s equipment was transported on standard railway wagons. For road travel, the Karl mortar was disassembled using a 35-tonne crane and loaded onto special heavy-duty trailers. The gun was removed from the carrier, broken down into three pieces and placed on three 16-wheel trailers – one for the barrel and breech block, one for the cradle and carriage (with lower recoil mechanism) and one for the upper recoil mechanism and loading tray. The tracked carrier was driven under its own power onto a 24-wheel trailer. Half-tracked artillery tractors were used to tow the trailers. To cross bridges, the tracked carrier had to be removed from its trailer, driven separately across the bridge and reloaded onto the trailer for further transport. Getting a Karl mortar into action at the front was an arduous task. It was transported by rail to a rail head, off-loaded, disassembled and then loaded onto road trailers. Artillery tractors towed the loaded trailers to a location near the firing sites, where the mortars were re-assembled and then driven under their own power into firing position. The process was repeated in reverse order to withdraw the Karl mortars from action. A collapsible gantry crane accompanied the mortars wherever they went. 10