42 cm Gamma Mörser The 42 cm " Gamma Mörser " as it was known in World War II or , originally , the 42 cm " kurze Marinekanone " L / 16 ( German for " short Naval gun with 16 caliber barrel " ) was a German siege howitzer . It was one in a series of super - heavy siege guns developed by Krupp before World War I . During the war , the gun was used to attack the Kaunas Fortress . The sole howitzer that survived World War I was used in World War II to attack the Maginot Line and the fortress of Sevastopol . Design and history . Well before World War I , Krupp began development of a series of super - heavy siege guns intended to crack the armored fortresses being built by Germany ' s neighbours . The " Gamma " was the third major design in this series , hence the name of " Gamma - Gerät ( Gamma device ) " , and was basically an enlarged " 30 . 5 cm Beta - Gerät " . The Krupp company also had relevant prior experience building 42 cm guns ; a 33 calibres long , 122 ton , brown powder coastal gun had even been exhibited in Chicago at the 1893 World ' s Columbian Exposition . ( This was a rebored 40 cm test gun that had served as prototype for the four 40 cm L / 35 guns of 121 tons delivered to Italy for mounting in coastal twin turrets at La Spezia and Taranto . ) For transport , the Gamma broke down into ten loads . It was a " Bettungsgeschütz " ( bedding - gun ) that had to be fired from a concrete platform . This was a tactical limitation and demanded extensive planning since the concrete had to cure , which could take up to a week , before the " Gamma " could be assembled . Assembly took a couple of days before it was ready to fire , even with the aid of a rail - mounted traveling crane . The impetus from the Prussia n General Staff to equip the army with large siege gun first came from one young officer , Max Bauer , who soon after his 1905 ( initially temporary ) appointment to the Fortress Department of the Staff , started to lobby his superiors . He soon won over Erich Ludendorff , and he engaged in correspondence with Rausenberger of Krupp . By April 1909 , a 42 cm prototype was ready for test firing at Krupps . Based on Bauer ' s correspondence , these tests were apparently very promising . In early 1911 , the gun was delivered for more testing by artillery proving experts . These tests also impressed Ludendorff , who was now head of the Mobilization Department of the Staff , and transferred Bauer to a permanent assignment in his own department . The new gun even convinced Ludendorff to resurrect the idea of smashing through France ' s fortress wall in a double envelopment move . Ludendorff proposed to attack the massive fort complexes of Verdun and Toul - Nancy in addition to the assault on Belgium , which had been the doctrinaire orthodoxy of the Schlieffen Plan for about 15 years . Ludendorff calculated that his alternative required eight 42 cm Gamma Devices and 16 Beta 30 . 5 cm mortars . However , the War Ministry Artillery Department , especially Karl Justrow , were skeptical of the mobility of the Gamma gun , as well as of the ammunition costs of Ludendorff ' s double envelopment plan . The Ministry wanted a more mobile 42 cm howitzer , and placed its own orders for a 44 ton howitzer , the " M - Gerät " ( " M device " , but popularly known as " Dicke Berta " ) , which was less powerful and had shorter range , but was transportable by tractors over land , while the Gamma device required railroads . An angry compromise resulted , in which both types were built . Between 1913 and 1914 , four more Gamma Devices were built , ( raising the pre - war production total to five ) , and two M Devices were also built in this period . Five more Gamma devices were built during the war . Like the " Beta - Gerät " , it was virtually unique among German World War I – era artillery in using a Welin interrupted - screw breech . It used a cartridge case even though its breech design did not require one to provide the necessary seal to prevent the escape of combustion gases . Possibly this was done to speed up its rate of fire , or because virtually every other German artillery piece used cartridge cases rather than bagged powder . It used a loading system to move ammunition from the ground up to the breech . An armored gunhouse for protection against shell fragments ( " Splitterschutz - Panzerkasten " ) could be fitted , and at least the Becker battery ( KMK no . 2 ) was photographed deployed this way during the 1914 campaign in Belgium . The surviving gun gained a much more elaborate firing platform . It is unclear what other changes the Germans made to the surviving gun . It was hidden at Krupp ' s proving ground at Meppen and was recommissioned during the 1930s to test concrete - piercing rounds . The Germans deployed it against the Maginot Line , and at the Siege of Sevastopol . Ammunition . Details are lacking on the ammunition it used during the First World War , other than it used two different shells , the original HE shell of at some per second and a lighter 1 , 680 pound ( 760 kg ) shell that it shared with its successor , the 42 cm howitzer commonly called Big Bertha . In World War II , it used a concrete - piercing shell ( " 42 cm Sprgr Be " ) weighing , propelled by up to four increments of powder , weighing in total .