42cm kurze Marinekanone 14 L/12 in Räderlafette M-Gerät


The 42cm kurze Marinekanone 14 L/12 in Räderlafette (Short Naval Cannon 14 L/12), M-Gerät or 'Big Bertha' was a massive 420mm howitzer that played a major part in the German victories early in the First World War, but that slowly faded from significance as the war developed.

Before the First World War Krupp had produced a series of designs for heavy guns and howitzers intended to deal with the strong Belgian forts. These threatened to block the German right wing during any attempt to implement the Schlieffen Plan, and so a way of dealing with them was urgently required. These efforts produced the Gamma howitzer, a massive 420mm weapon that had to be dismantled and transported by train, but that was accurate and could defeat any existing fixed fortification.

The German staff liked the firepower offered by Gamma, but wanted a more mobile version that could be moved by road. Krupp already had some experience of producing heavy siege guns on wheeled carriages, starting with the 28cm howitzer L/12 in Räderlafette (i.R). This was followed by the 28cm howitzer L/14 i.R, and finally the 30.5cm howitzer L/17 in Räderlafette or Beta i.R. of 1910-1912.

In 1911 the German artillery branch drew up a specification for a wheeled 42cm howitzer, which was named the 42cm kurze Marinekanone 14 L/12 in Räderlafette or M-Gerät.  ('Equipment 'M', as it was originally expected to fire thin walled shells resembling mines). The M-Gerät was a new design and not a development of the static Gamma-Gerät. It had a shorter barrel, with thinner walls and a sliding-wedge breech. As a result it had significantly less range - 9,300m instead of 12,500-14,100m, less destructive power and less accuracy.

Although the resulting weapon looks as if it could be towed intact, this wasn't the case. It was actually designed to be dismantled into five parts, each of which could be towed behind a single tractor, and then re-assembled fairly easily at its destination. The first wagon carried a gantry crane and the equipment needed to assemble and disassemble the barrel. The second had the gun platform and the rails for moving the carriage into place. The third carried the cradle of the barrel and the trail spade. The fourth carried the wheeled carriage and trail. The fifth carried the barrel and breechblock. In good conditions it took six hours to emplace the M-Gerät, half the time it took to assemble the 30.5cm Beta-Gerät and a quarter of the 24 hours required for the Gamma.

Two were just about complete at the outbreak of the First World War. Two more were ordered on 31 July 1914, two on 28 August 1914 and two on 11 November. These weapons were delivered between mid-August 1915 and early 1916. A total of twelve had been built by the end of the war.

The 420mm weapon had a 6.72m barrel, mounted over the wheels on the massive carriage. It fired 810kg shells that penetrated deep into the ground before exploding, causing shock waves that hit deep inside the fortresses. Even if the concrete walls weren't destroyed, the defender's morale soon broke under the constant bombardment.

The new weapon soon gained the nickname 'dicke Bertha' or 'Fat Bertha', generally translated into English as 'Big Bertha'. The guns were only just ready in time to take part in the early campaigns of the First World War, when the first two to be completed were operated by a special unit, kurz Marine Kanone 3. Big Bertha played a major part in forcing the surrender of the forts at Liege and then at Namur. They were then moved to the Russian front, where they had similar successes. However as the war developed, they began to lose their impact. The sort of concrete fortifications they were designed to destroy lost their importance. They took part in the battle of Verdun, but the French didn't even notice! They also wore out rather quickly, and then became very inaccurate. They also suffered from a series of pre-mature detonations, which destroyed a number of them. Despite these failings, they had played a major role in the early German successes of 1914. They disappeared after the end of the First World War, although at least one of the original 'Gamma' howitzers survived to see service at the siege of Sevastopol in 1942.

The first of the German siege artillery batteries to get into combat was KMK Battery 3, which was equipped with two M-Gerät howitzers. This battery arrived at Liege a week after the start of the siege. At this point only two of the twelve forts around the city had surrendered, and the advance was being held up. On 12 August the battery emplaced its two guns facing Fort Pontisse. They opened fire at 1840hrs, and the eighth shot hit the target, causing the garrison to raise the white flag. The surrender negotiations failed at this stage, but after four hours of bombardment on 13 August the garrison surrendered. This only required 51 rounds from the two heavy howitzers. The battery then moved to Fort Liers, which surrendered before they opened fire. On August 15 they opened fire on Fort Loncin, which exploded after the 25th shell hit an ammo magazine triggering a massive explosion. On the following day the two remaining forts surrendered.

KMK Battery 3 then moved on to take part in the siege of Namur, operating alongside eight Skoda 30.5cm M.11 mortars. The two M-Geräts opened fire on 22 August, bombarding Fort Marchovelette. The Skoda guns were the first to score a success, when Fort Cognelee surrendered at midday on 23 August. The M-Gerät achieved a more dramatic success two hours later, when the 50th round from the battery hit an ammo magazine and destroyed Fort Marchovelette. The battery then moved on to bombard Fort Suarlée, which was soon forced to surrender. The entire siege had only lasted five days.

The battery then moved to Maubeuge, where it took part in a bombardment that began at the end of August.

Battery KMK 3 then took its M-Geräts to Antwerp. The battery opened fire on 30 September, hitting Fort Lierre. After the fall of that fort it opened fire on Fort Kessel, which surrendered within a day. The howitzers were then able to move up to bombard Fort Broechem, which fell after two days.

The M-Gerät made its combat debut on the Eastern Front with KMK Battery 6, during the siege of Przemysl. At first this was an Austrian affair, but in late May the German siege artillery joined in. The bombardment began on 30 May, and the Russians abandoned the fortress only five days later.

Three Gamma-Geräts, two M-Geräts and four Beta-Geräts took part in the successful siege of Kovno in August 1915.

In the same month four M-Geräts took part in the operations that isolated the great Russian fortress at Novogeorgievsk, taking three key fortifications further to the east, before joining the main siege. The fortress had been expected to hold out for months, but it fell after only six days.

Two M-Geräts took part in the German invasion of Serbia in 1915, bombarding Serbian strong points.

Eight M-Geräts took part in the battle of Verdun, but they had less impact than in 1914. The French forts around Verdun turned out to be strong enough to resist 42cm shells, although serious damage was done to their exteriors. Worse, four of the M-Geräts were destroyed when faulty shells exploded in their barrels.

The siege guns lost their importance in the last years of the war, although they were used to support the spring offensives of 1918. At the end of the war M-Geräts were handed over to the Americans, and taken to the Aberdeen Proving Grounds for evaluation. They were scrapped in 1943 and the early 1950s respectively.


M-Gerät/ dicke Bertha/ Big Bertha


420mm/ 16.54in

Barrel Length

6.72m/ 22ft 0.7in

Weight for transport


Weight in action

42,600kg/ 93,915lb


0 to 65 degrees


20 degrees

Shell Weight

810kg/ 1,786lb

Muzzle Velocity

426m/ 1,400ft per second

Maximum Range

9,300m/ 10.170ft

Rate of Fire

1 round every five minutes

German Artillery 1914-1918, Wolfgang Fleischer. Covers over 100 guns used by the German Army and shore detachments of the Navy during the First World War, a conflict largely dominated by artillery. Each one gets a brief description, a set of technical stats and a good picture. Shows the wide range of gun types and sizes used by the Germans during the First World War, and the way in which they evolved to deal with the unexpected challenges of trench warfare. [read full review]
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Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (28 November 2017), 42cm kurze Marinekanone 14 L/12 in Räderlafette M-Gerät , http://www.historyofwar.org/articles/weapons_42cm_big_bertha.html

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