The M-Gerät 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.

When the First World War broke out, the two M-Gerät guns, still prototypes, were sent to Liège, Belgium, and destroyed Forts Pontisse and Loncin.

Due to losses from faulty ammunition and Allied counter-battery artillery, a smaller-calibre (30.5 cm (12.0 in)) gun called the Beta-M-Gerät was built and fielded from 1916 until the end of the war.

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.

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.

[1][2] 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.

By the 1880s the barrel diameter of the German Army's most powerful gun, the 21 cm (8.3 in) field howitzer, was no longer adequate against fortresses.

To be able to reduce French and Belgian fortresses, the Artillerieprüfungskommission [de] (Artillery Test Commission, APK) formed a partnership with Krupp AG in 1893.

The first result of this partnership was a 30.5 cm (12.0 in) mortar, accepted into service four years later as the schwerer Küstenmörser L/8, but known as the Beta-Gerät (Beta Apparatus) to disguise its purpose as a siege gun.

[6] 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 Beta-Gerät.

Although the Gamma-Gerät 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.

Test firing, at one point observed by Kaiser Wilhelm II, began in February 1914, and Krupp estimated that the M-Gerät would be complete by October 1914.

[11][12][13] Post-prototype M-Gerät guns had a crew platform in front of the blast shield, a detachable breech, and solid wheels.

To move across open country, the wagon wheels were fitted with articulated feet called radgürteln to reduce their ground pressure.

[17] The 30.5-centimetre Beta-M-Gerät, called the schwere Kartaune L/30, was developed in late 1917 to replace M-Gerät guns that had been rendered inoperable by premature detonation of shells.

Beginning in early 1916, German siege guns began to suffer internal explosions due to faulty ammunition.

[20] 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.

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.

[27] 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.

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.

[35] The 42-centimetre guns had to suppress the artillery of Forts Vaux, Douaumont, Souville and Moulainville [fr] but were unable to penetrate the concrete of the modern fortresses.

Those that remained primarily shelled field works and often had low survivability due to malfunctions or Allied counter-battery artillery.

KMK Battery 10 lost one M-Gerät to a premature detonation and the other to British warships near Ostend in August 1917 and was rearmed with captured Russian 12 cm (4.7 in) howitzers.

The last deployment of M-Gerät guns on the Eastern Front was in October 1915, when KMK Battery 6 was attached to the German 11th Army as it invaded Serbia.

[41][42] The name has since entered the public consciousness, for example being applied as a moniker to a line of Callaway golf clubs and a satirical French-language magazine and a bond-buying policy by Mario Draghi, President of the European Central Bank.

One was taken to the United States, evaluated and then put on display at the Aberdeen Proving Ground, while the other was left unassembled in its transport configuration.

World War I veteran Emil Cherubin built a replica of an M-Gerät, which toured Germany and appeared on a few postage stamps.