21cm Kanone 12 (Eisenbahn)

The 21cm Kanone 12 (Eisenbahn) was a vanity project produced by the German Army, and consumed a vast amount of effort and resources without having any significant military value.

The first theoretical work on the weapon took place late in the First World War, after the German Army decided that it needed to have an equivalent to the Navy’s ‘Paris Gun’. Work continued at a very low level during the 1920s, and sped up in the 1930s, and by 1935 the project had reached the stage of laboratory experiments. These were scaled up to work with a 105mm barrel. This suggested that fitting splines to the shell that would fit into the rifling of the barrel would reduce the wear caused by the large amount of propellant needed to achieve the required range.

The 21cm barrel was produced in 1937. This was 33.34m long (L/158), and required external bracing to stop it from bending under its own weight. The gun was carried on a large carriage that was supported on bogies at either end. Each upper bogie supported two lower bogies, with four wheels on each side and one end and five at the other, for a total of 18 wheels on each side. The 21m K 12 (E) wasn’t quick to get into action. Although it could be moved into place easily enough, a large pit had to be dug under the tracks to provide space for the barrel recoil. It also required a curving section of track to allow it to be aimed, as it had to fire along the length of its carriage. Tests showed that the new weapon had a maximum range of 120 km (75 miles), giving it the long range required by the German Army. However its shell didn’t actually carry much of a payload, making the entire project rather pointless.

The 21cm K 12 (E) entered service in 1938, and fired in anger for the first time in 1940. This was a fairly short-lived bombardment of England from the Pas de Calais, in which one shell was recorded at Rainham, 55 miles from the firing point. If any shells reached further inland, they didn’t come to anyone’s attention, probably because the small payload meant that they didn’t stand out in the middle of the German bombing campaign.

A second gun was produced, with a new carriage that moved the gun into a higher position, removing the need to dig a pit. The two guns were used by Eisenbahnbatterie 701, which only ever operated them one at a time. Whichever gun was in use moved between the Dutch coast and the Pas de Calais, firing an occasional shell. The second gun was captured during the Allied advance into the Netherlands in 1945.

At one point the Germans considering moving one 21cm K12 (E) to the southern tip of Sicily, from where it could just about reach Malta, 110km away, but nothing came of that plan.


21cm K 12 (E)


21.1cm (8.3in)

Barrel Length

33.34m (109ft 4.6in)

Weight for transport


Weight in action

317 tons


25 to 55 degrees


0.23 degrees

Shell Weight

107.5kg (237lb)

Muzzle Velocity

1,625m. sec

Maximum Range

115km (71.5 miles)

Rate of Fire

6 rounds/ hour

Railway Guns of World War II, Steven J. Zaloga. Although the heyday of the railway gun came during the First World War, the most famous example of the type, the massive German 80cm K(E) guns 'Dora' and 'Gustav', came from the Second World War. In reality these were useless vanity projects, but as this book makes clear every major combatant used a least a handful of railway guns during the Second World War. This book combines  brief technical descriptions of each country's railway guns with a look at their combat service [read full review]
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How to cite this article: Rickard, J (28 June 2018), 21cm Kanone 12 (Eisenbahn) , http://www.historyofwar.org/articles/weapons_21cm_kanone_12_eisenbahn.html

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