The 42 centimeter 14 L/12 (short naval cannon), or Minenwerfer-Gerät (M-Gerät), popularly known by the name of Big Bertha, was a German siege howitzer built by Krupp AG in Essen, Germany and fielded by the Imperial German Army from 1914 to 1918. The had a calibre barrel, making it one of the largest artillery pieces ever fielded.
The designed in 1911 as an iteration of earlier super-heavy German siege guns intended to break modern fortresses in France and Belgium and entered production in 1912. Test firing began in early 1914 and the gun was estimated to be finished by October 1914. When the First World War broke out, the two guns, still prototypes, were sent to Liège, Belgium, and destroyed Forts Pontisse and Loncin. German soldiers bestowed the gun with the nickname "Big Bertha", which then spread through German newspapers to the Allies, who used it as a nickname for all super-heavy German artillery. The Paris Gun, a railway gun used to bomb Paris in 1918, has historically been confused for the M-Gerät.
Due to losses from faulty ammunition and Allied counter-battery artillery, a smaller-calibre () gun called the was built and fielded from 1916 until the end of the war. It had a longer and heavier barrel that was mated to the 's carriage but was found to be less effective than the base gun.
Development and design The quick advancement of artillery technology beginning in the 1850s provoked an arms race between artillery and military architecture. Rifled artillery could now fire out of range of fortress guns, so military architects began placing forts in rings around cities or in barriers to block approaching armies. These forts were vulnerable to new artillery shells, which could penetrate earth to destroy masonry underground. In response, star forts evolved into polygonal forts, mostly underground and made of concrete with guns mounted in armoured, rotating casemates. Combining rings and barriers, France created a vast fortified zone on its border with Germany, while Belgium began construction of the National Redoubt in 1888.
The German Empire also fortified its borders, but Chief of the General Staff Helmuth von Moltke the Elder desired the ability to break through Franco-Belgian fortifications. Although German artillery had been effective during the Franco-Prussian War, it had been allowed to stagnate. By the 1880s the barrel diameter of the German Army's most powerful gun, the field howitzer, was no longer adequate against fortresses. Moltke began requesting more powerful guns that same decade. More powerful artillery became essential to his successor, Alfred von Schlieffen, who planned quickly to defeat France by sweeping through Belgium (the Schlieffen Plan) in response to the 1893 Franco-Russian Alliance. To be able to reduce French and Belgian fortresses, the (Artillery Test Commission, APK) formed a partnership with Krupp AG in 1893. The first result of this partnership was a mortar, accepted into service four years later as the L/8, but known as the (Beta Apparatus) to disguise its purpose as a siege gun. Tests in the mid-1890s showed that the could not destroy French or Belgian forts, even with improved shells. Interest in a more powerful siege gun waned until the Russo-Japanese War, during which the Japanese Army used 28 cm howitzer L/10 ( coastal guns) brought from Japan to end the 11-month long Siege of Port Arthur.
In 1906, Helmuth von Moltke the Younger became Chief of the General Staff and instructed the APK to study and improve the performance of the . The APK recommended a more powerful gun, with a diameter as large as , but the German Army opted for a 30.5-centimetre howitzer, the 09 and a gun. Design and testing for the began in 1906 and lasted until 1911. Although the had the destructive power the General Staff required and could outrange French and Belgian fort guns, it could only be emplaced near rail lines and took 24 hours to prepare. As early as 1907, Krupp began development of siege artillery transported by gun carriage. Testing resulted in a howitzer transportable over road and countryside but it was rejected by the APK, as was Krupp's 30.5-centimetre model. Finally, in late 1911, Krupp and the APK developed a wheeled 42-centimetre howitzer, the 42-centimetre 14 L/12 or (). The APK ordered its first in July 1912 and another in February 1913. Tests of the gun's mobility began in December 1913 and found that gas-powered tractors were best for pulling it. Test firing, at one point observed by Kaiser Wilhelm II, began in February 1914, and Krupp estimated that the would be complete by October 1914.
Design and production Assembled and emplaced, the weighed , was tall, long and wide, and sat on a steel base with a spade for bracing. This spade could be lifted out of the ground while the was emplaced to move it, giving it a traverse of 360°. The gun was breech loaded, using a horizontally-sliding breech block and had a barrel that could be elevated to a maximum of 65°. The had a muzzle velocity of about and a maximum range of . Post-prototype guns had a crew platform in front of the blast shield, a detachable breech, and solid wheels. The APK ordered the first in July 1912, delivered the following December, and a second in February 1913. Another two guns were ordered before the First World War on 31 July 1914, and then two more on 28 August and another pair on 11 November. Krupp eventually built 12 howitzers.
The had to be assembled for firing and for transport was dismantled and towed in five wagons. These wagons, weighing each, were designed to hold a specific portion of the M-Gerät, sans the gun carriage, which was its own wagon. These were towed by purpose-built, gas-powered tractors as the wagons were too heavy to be pulled by horses. To move across open country, the wagon wheels were fitted with articulated feet called to reduce their ground pressure. Under optimal circumstances, the tractors and wagons could move at .
The 30.5-centimetre , called the L/30, was developed in late 1917 to replace guns that had been rendered inoperable by premature detonation of shells. To increase the range of the and lower the likelihood of premature detonation, the APK selected a -long, naval barrel to be mounted onto the chassis of the . Two large spring cylinders were added to the front of the gun to counterbalance the new barrel, which had to be carried in a new carriage weighing . Fully assembled, the weighed and had a maximum range of . The propellant used to achieve that range caused three of the four guns to explode, forcing their crews to limit its range by , defeating the purpose of the longer L/30 barrel. Only four Beta-M-Gerät guns were modified from two M-Gerät guns and two guns (a one- to two-month-long process per gun), but 12 L/30 barrels were built.
+ "Gerät" siege artillery variants Name Calibre Weight Range Rate of fire Time to emplace (hours) "Big Bertha" 8 shells an hour 5–6 24 7–8 09 12 shells an hour 12 15 shells an hour
Ammunition
German siege artillery had three types of projectiles: armour-piercing, high-explosive and intermediate. The armour-piercing shell was designed to smash through concrete and metal armour but was largely ineffective against reinforced concrete. High-explosive shells were fitted with two charges and could be set to have no delay, a short delay or a long delay. If set to "no delay" the shell burst on impact. If set to a delayed detonation, it could penetrate up to of earth. Finally, the intermediate, or "short shell", weighed half as much as the high-explosive shell and was fitted with a ballistic tip for range and accuracy. Shells for the 42-centimetre guns were generally long, weighed between , and were propelled via primer loaded into the gun with a brass casing. Siege artillery shells were produced in limited runs of varying quality. Beginning in early 1916, German siege guns began to suffer internal explosions due to faulty ammunition. Crews were required to disembark from the gun before firing via a lanyard.
Service history The (KMK) batteries that formed with M-Gerät guns were 3 (2 August 1914), 5 (June 1915), 6 (Summer 1915) and 7 (early 1916). Battery 3 was split in half in April 1916 to form 10 with a single M-Gerät each. The four Beta-M-Gerät guns produced were fielded by KMK Batteries 8 and 10 after their M-Gerät gun barrels had been destroyed by premature detonation. When the German Army was reorganised in late 1918, only Battery 5 had M-Gerät guns, and (SKM) Battery 3 was assigned the remaining two Beta-M-Gerät guns.
Western Front
By June 1914, the prototype M-Gerät howitzers had returned to Essen for final adjustments and would have been formed into a reserve artillery battery on completion in October. On 2 August 1914, they were organised into KMK Battery 3 and sent to the Western Front with 240 men. On 4 August, the 1st Army arrived near Liège, Belgium, the first objective of the Schlieffen Plan and began the Battle of Liège. Although German troops entered the city on 7 August, its forts were firing upon the road to be taken by the 2nd Army and had to be reduced. Heavy artillery began their attack on 8 August. KMK Battery 3 was the first siege battery sent into battle to bombard the Fort de Pontisse on 12 August, which surrendered after two days. The battery next moved to the Fort de Liers but the fort surrendered as the battery was being emplaced. KMK Battery 3 relocated to the Fort de Loncin, where Gérard Leman directed the defence of Liège. Firing commenced on 15 August and lasted two hours, as the 25th shot fired struck a magazine and caused an explosion that destroyed the fort. The Germans carried Leman, unconscious, out of Loncin, and the last two forts, Hollogne and Flémalle, capitulated on 16 August.
With Liège captured, the 1st Army continued north-west while the 2nd and 3rd Armies marched to Namur, whose forts were undermanned, unmaintained, and poorly stocked with ammunition. The 2nd Army arrived on 20 August 1914 to open the Siege of Namur, but began their main attacks the following day with 400 pieces of artillery. KMK Battery 3 fired upon the Fort de Marchovelette, which was destroyed on 23 August by a magazine explosion. The battery shifted its fire to the Fort de Maizeret, already under bombardment by four Austro-Hungarian Skoda 30.5-centimetre guns, and compelled its surrender. With the eastern forts occupied, the Germans entered Namur and the remaining Belgian forces evacuated from the city.
Following the defeat of the Western Allies at Charleroi and at Mons, the British Expeditionary Force withdrew past Maubeuge, their base of operations after arriving in France. On 24 August 1914, the advancing Germans arrived at the fortresses of Maubeuge and began the Siege of Maubeuge and its garrison of 45,000 soldiers. The next day, the VII Reserve Corps were left behind the main German armies to take the city. Bombardment of the forts began on 30 August, with KMK Battery 3 tasked with reducing (Fort Sarts) but it mistakenly shelled an interval fortification in front of Sarts. By 5 September, a hole in the fortress ring had been opened by German 21-centimetre guns, but they had by now exhausted their ammunition. To widen that gap, the siege guns then expended their remaining ammunition against Forts Leveau, Héronfontaine, and Cerfontaine on 7 September, and destroyed them in quick succession. The two remaining French forts surrendered that same day and the Germans occupied Maubeuge on 8 September.