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| Mimoyecques - Entrance to V3 Cannon site |
The V3 Cannon was a multi-charge gun which was developed to fire hundreds of 140 kg (300 pound) projectiles per hour up to a range of 165 km (103 miles).
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| V3 Projectile |
The design was based upon plans captured from the French in 1940. In 1918, the German Army began bombardment of Paris using a 230mm Krupp Rail Gun which had a range of 130 km (81 miles). In response the French began their own long range artillery development experimenting with a multi-charge gun. The signing of the Armistice in November 1918 meant the gun never reached prototype stage, the plans being archived.
The Germans began their own development based upon the French plans, but soon found issues with the use of multiple charges as they would quickly degrade the gun barrel. Their solution was to have a series of small charges along the length of the barrel in small tubes at the side. As the projectile moved along the barrel each charge would fire in turn increasing its velocity achieving a muzzle velocity of 1,500 metres per seconds on departing the barrel. They built their first prototype which was successfully tested in April / May 1943. The V3 was also known as the Hochdruckpumpe (High Pressure Pump), to disguise it's intended use.
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| V3 Hochdruckpumpe prototype Laatzig testing facility |
Hitler decided that the V3 Cannon would supplement the V1 and V2 weapons, the gun would have the specific role of bombarding London. The expected rate of fire was 10 rounds per minute, delivering 600 rounds per hour on London.
The plan was to build two batteries, each consisting of 5 shafts, with 5 barrels per shaft, a total of 50 guns.
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| Mimoyecques site plan |
A site at Mimoyecques, 165 km (103 miles) from London was selected for the location of the V3. Construction in a limestone hill began in September 1943. Two separate facilities were initiated connected by a railway tunnel. Difficulties in construction resulted in only the Eastern Battery being developed.
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| By Sanders, T.R.B. - Investigation of the "Heavy" Crossbow installations in Northern France. Report by the Sanders Mission to the Chairman of the Crossbow Committee. Technical details; Vol III, "Mimoyecques", Public Domain, https://commons.wikimedia.org/w/index.php?curid=15577156 |
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| By Sanders, T.R.B. - Investigation of the "Heavy" Crossbow installations in Northern France. Report by the Sanders Mission to the Chairman of the Crossbow Committee. Technical details; Vol III, "Mimoyecques", Public Domain, https://commons.wikimedia.org/w/index.php?curid=15577156 |
The shafts were set at an angle of 50 degrees (889 mils) and reached a depth of 105 metres (344 feet). Each drift was set on bearing of 299 degrees (5,316 mils), a direct line with Westminster Bridge.
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| Model of Mimoyecques site showing rail tunnel entrance and gun shafts |
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| Mimoyecques shaft with reconstructed V3 Gun |
Intelligent reports and aerial reconnaissance detected the work at Mimoyecques. The true purpose of the facility was not known, though it was suspected it would involve rockets and long range artillery.
Several bombing raids were conducted between November and June 1944 inflicting minimal damage.
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| Mimoyecques site following bombing raids |
On the 4th July 617 Squadron RAF began bombing the site with 12,000 lb Tall Boy bombs. The damage inflicted was such that the site was abandoned by the end of July 1944.
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| Lancaster dropping Tall Boy Bomb |