The 42-centimetre 14 L/12 (short naval cannon), or Minenwerfer-Gerät (M-Gerät), popularly known by the nickname 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.