30.5cm Mortar L/8 / Beta-Gerät

The 30.5cm schwere Küstenmörser L/8 or Beta-Gerät was the first in a series of designs that eventually produced the famous 'Big Bertha' howitzers that played a part in the early German victories in 1914.

The beta-gerät was developed in response to a key problem facing the German military - the ever increasing number of strong fortifications just over their borders that would have to be besieged in the event of any war. This was especially true for the famous Schlieffen plan, which required the rapid destruction of a series of Belgian and French fortifications if it was to have any chance of success. None of the existing German artillery pieces had the range or firepower to deal with these forts.

The beta-gerät was the first attempt to deal with this problem. It was developed by the Artillery Test Commission and Krupp in 1893, and was based on existing coastal defence mortars. These had the firepower to penetrate the armoured decks of warships, but not the accuracy to deal with a small moving target. However that wouldn't be a problem with a fortress, and so the very heavy mortar was the ideal weapon.

The Krupp design was the first large calibre gun in the German army to have a recoil mechanism (in this case a gravity recoil system) and a breech. It was a heavy weapon - 30,000kg in the firing position, and needed to be placed on a solid wooden foundation, weighting around 10,000kg. A base plate was then placed on top of the foundations, with the carriage on top of that, which in turn carried the barrel. The weapon had to be split into three parts to be transported - barrel, carriage and base place. Each two mortar battery needed 12 railcars just for the mortars and their equipment (3 for each mortar), and 31 railcars when all of the personnel and other items were moved. It took twelve hours to assemble the gun in a new firing position. It needed either traction engines or narrow gauge railways to move the components from the railhead to the firing position.

In 1897 an order was placed for six guns, enough for three two-gun batteries. Another three followed in 1906, for a total of nine, of which eight were still in use at the start of the First World War. Eight of the guns were allocated to four beta batteries, numbered 1-4. Battery No.5 used the Beta-Gerät 09. At first all five used rail transport, but in 1912 nos.2 and 5 were given road wagons and steam tractors.

The beta-gerät was a promising weapon, but it wasn't quite powerful enough for its purpose. It could penetrate concrete cupolas of up to 250mm thickness, but by the 1890s the French were beginning to build fortresses with stronger protection. Its range of 8,200m was longer than that of any Belgian fortress guns of the 1890s, but not of the French guns, so it would have to advance into the danger zone to fire.

Although only eight were still in use in 1914, the beta-gerät saw service with the siege artillery throughout the First World War.

The first to enter combat were the two mortars with SKM battery 1, which took part in the siege of Liege. However the slow rate of emplacement counted against them at first, when their first target, Fort Chaudfontaine, surrendered before they were ready to open fire. On 16 August they were finally ready to open fire against Forts Hollogne and Flémalle, when they surrendered. An effort was made to move them to Namur to take part in that siege, but damage to the rail network prevented them from arriving in time.

Battery SKM 1 then took its Beta-Geräts to Antwerp. The battery opened fire on 28 September, hitting Fort Wavre-Sainte-Catherine. The fort surrendered on 29 September after a powder magazine was destroyed by a Gamma-Gerät shell. The battery then opened fire on Fort Breendonk, which held out for three days.

In Lorraine two Beta mortars of SKM Battery 2 took part in the siege of Fort Manonviller (25-27 August 1914), but they were slow to get into action, and the siege artillery didn't play a major part in this battle. The battery then took part in a failed attempt to break through the line of forts south of Verdun (9 September-16 October).

Three Gamma-Geräts, two M-Geräts and four Beta-Geräts took part in the successful siege of Kovno in August 1915.

After this the 30.5cm siege mortars began to fade away. Their shorter range meant they were exposed to Allied counter battery fire, and the impact of their larger shells was hard to notice in the massive artillery bombardments of the period. None survived the end of the First World War.


30.5cm schwere Küstenmörser L/8



Barrel Length

2,440mm (L/8)

Weight for transport


Weight in action



50-60 degrees


60 degrees

Shell Weight


Muzzle Velocity

310-336 m/sec

Maximum Range

8,200m with AP shells
8,800m with HE shells

Rate of Fire

One round every two minutes

German Artillery 1914-1918, Wolfgang Fleischer. Covers over 100 guns used by the German Army and shore detachments of the Navy during the First World War, a conflict largely dominated by artillery. Each one gets a brief description, a set of technical stats and a good picture. Shows the wide range of gun types and sizes used by the Germans during the First World War, and the way in which they evolved to deal with the unexpected challenges of trench warfare. [read full review]
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Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (20 November 2017), 30.5cm Mortar L/8 / Beta-Gerät , http://www.historyofwar.org/articles/weapons_30_5cm_mortar_L8_beta_gerat.html

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