Formerly stored at the Gâvres Marine base, this colossus has been restored and installed on the site where the Germans used several of these surviving ALVF guns.
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Rear view of the impressive cradle with the four rear brakes and trunnions. This 1914 Nr4 tube does not appear in those listed for the ALVF (cradle or sliding mounts). It may have been a reserve.
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Markings on the breech: "34cm Mle 1912 R 1914 - R 3 1915 / 34 Mle 1912 Te 380 - R 1914 N 4 TB - P 65050 K (barré) 64700 K". Ce tube aurait donc été réalésé au calibre de 380mm
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Historic context :
The frantic arms race between Great Britain, Germany, France, and many other powers at the end of the 19th century and the beginning of the 20th century took on particularly excessive proportions at sea, with each nation spending phenomenal amounts of money to build battleships that were increasingly bigger, better armored, better armed... and quickly surpassed.
Just before the war, the latest warships generation resulting from this situation was represented by the ‘Super Dreadnoughts’, and France, which had remained relatively inactive in this naval arms race for budgetary reasons, decided in 1912 to build four ships of this type, called the ‘Bretagne class’ after the name of the first of them. A new gun was designed specifically to arm the turrets, with an impressive caliber of '34 cm model 1912'.
But by the end of 1914, while these ships were under construction, it became clear that the war was bogged down in a purely land-based conflict, and that the mega naval battle that would allow these floating monsters to clash would never take place, with the major skirmishes mostly ending in a ‘draw’, and the submarine warfare encouraging the navies not to venture their best units too far out to sea.
As a result, the ambitious construction programs were halted. In our French case, three of the four ships ordered were delivered in 1915, and a second order for six ships of the Provence class was canceled while work was already underway. This situation left several 34 cm tubes surplus to requirements, and in 1915 it was decided to convert the six tubes available at that time into heavy land-based artillery that could be transported by rail.
The conversion was entrusted to the 'Société des Forges et Aciéries de la Marine et de Homécourt'. Its workshops in Saint Chamond designed the 'Canon de 340 mm modèle 1912 sur affût-truck à berceau Saint Chamond' (‘340 mm model 1912 gun on a Saint Chamond cradle truck carriage’), which was delivered from 1916 and saw active service from then. Two of the six pieces were loaned to the US Army in 1918 to take part in the fighting in the Meuse-Argonne.
In this weapon, a ‘cradle’ enveloped the rear section of the naval gun barrel and incorporated a recoil damping system consisting of four hydraulic brake cylinders and a pneumatic recuperator. The assembly was connected by its wheels to a ‘truck’ consisting of a sheet metal crane mounted on two bogies with three axles each, for transport on standard railways.
For firing, a site was prepared with platforms, and the bogies were removed from under the crane, which then rested on a retractable central pivot and a screw jack at each of its four corners. These preparatory tasks took two to three days, and the actual setting up of the battery on a prepared site took one hour. A pit dug under the breech allowed it to be raised to high elevations (up to 42 degrees), and the central pivot allowed a modest horizontal deflection of 10 degrees. This piece was the most powerful in the French army with a range of up to 33 km !
Later, the Schneider company was commissioned to design a gun based on the same barrel but on a more practical sliding carriage, as this allowed it to be fired on rails arranged in a curved wedge, enabling it to be aimed in the desired direction and significantly reducing the time needed to set up the gun. Two examples of this 'Canon de 340 mm modèle 1912 sur affût à glissement Schneider' (“340 mm model 1912 gun on Schneider sliding carriage”) were delivered in 1917. Several pieces of both types were under construction when the armistice ended the conflict.
The equipment was still in service in June 1940 and was seized by the German army, which integrated it into the coastal defenses of France, including the Bégo battery site in Plouharnel on the Breton section of the Atlantic Wall.
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Technical data :
- Complete description : 340 mm gun M 1912 B on St Chamond craddle carriage or Schneider sliding carriage rail truck
- Design year : 1916
- Calibre : 340.00 mm
- Weight in firing position : 98.7 tons (barrel and breech weight 67.6 tons)
- Weight for transportation : 166 tons
- Tube length in calibres : 45.00 (grooved part only - total length 47.5 calibers)
- Grooves : 102 constant angle 4 degrees (or 5 or 6 depending on the model), to the right
- Projectile weight : 428 à 540 kg
- Initial speed : 800 to 867 m/s
- Fire rate : 1 round / 6 min
- Range : 33000 m
- Elevation range : +15 to +42 degrees
- Direction range : 10 degrees total range
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