| 42 cm Gamma Mörser | |
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Side view of a Gamma-Gerät |
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| Type | Super-Heavy Siege Howitzer |
| Place of origin | German Empire |
| Service history | |
| In service | 1909–1945 |
| Used by | German Empire Nazi Germany |
| Wars | World War I World War II |
| Production history | |
| Designer | Krupp |
| Designed | 1909–1912 |
| Manufacturer | Krupp |
| Number built | 10[1] |
| Specifications | |
| Weight | 140 tonnes (140 long tons; 150 short tons) |
| Barrel length | 6.723 metres (22 ft 0.7 in) L/16 |
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| Shell | separate-loading, case charge |
| Caliber | 419 millimetres (16.5 in) |
| Breech | Welin breech block |
| Recoil | hydro-pneumatic |
| Carriage | box |
| Elevation | +43° to 75° |
| Traverse | 46° |
| Rate of fire | 1 round per 8 minutes |
| Muzzle velocity | 420 m/s (1,400 ft/s) |
| Maximum range | 14,200 metres (15,500 yd) |
The 42 cm Gamma Mörser as it was known in World War II or, originally, the 42 cm kurze Marinekanone L/16 (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 that war the gun was used to attack the Kaunas Fortress. The one howitzer that survived World War I was used to attack the Maginot Line, the fortress of Sevastopol and bombarded Polish rebels in Warsaw.
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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 its neighbors. 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;[2] a 33 calibres long, 122 ton, brown powder coastal gun had even been exhibited in Chicago at the 1893 World's Columbian Exposition.[3] (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.[4][5])
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 real 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. Even then 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 Prussian General Staff to equip the army with large siege gun came first from a single 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 trough 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. The War Ministry Artillery Department, especially Karl Justrow, were however 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.[6] Between 1913 and 1914 four more Gamma Devices where built,[6] (raising the pre-war production total to five[1]), and two M Devices were also built in this period.[6] Five more Gamma devices were built during the war.[1][7]
Like the Beta-Gerät, it was virtually unique among German World War I–era artillery in using a Welin interrupted-screw breech. Oddly it used a cartridge case even though its breech design didn't 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 simply because virtually every other German artillery piece used cartridge cases rather than bagged powder. It used an interesting (chain-driven?) loading system to move ammunition from the ground up to the breech, which is the diagonal structure on the left in the picture to the right. It broke down into ten train loads for transport.
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 in the Belgium 1914 campaign.[8][9] The WWII Gamma also had one at Warsaw according to photographic evidence. The surviving gun gained a much more elaborate firing platform, as can be seen from the photos in the photo gallery linked to below. It's unclear what other changes the Germans made to the surviving gun, but the data presented here is for the howitzer in its World War II incarnation, but without the gunhouse.
Sources disagree on the number of Gammas built, although numbers up to ten are cited, but it is clear that only one survived the cutting torches of the Military Inter-Allied Commission of Control that enforced the dictates of the Versailles Peace Treaty. It was hidden at Krupp's proving ground at Meppen and was recommissioned during the Thirties to test concrete-piercing rounds. The Germans deployed it against the Maginot Line, the Siege of Sevastopol and the Warsaw Uprising in 1944.
Details are lacking on its ammunition used during the First World War, other than it used two different shells, the original HE shell of 1,953 pounds (886 kg) at some 1,200 feet (370 m) 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 1,003 kilograms (2,210 lb), propelled by up to four increments of powder, weighing in total 77.8 kilograms (172 lb).[10]
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