La Coupole
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La Coupole is the name of a Second World War V-2 rocket base south west of the French town of St Omer.
Set in a former limestone quarry close to the villages of Helfaut and Wizernes the complex was intended to be an impregnable underground production and launch facility for the rockets.
Work on the site was begun in October 1943 using slave labour under the direction of the Todt Organisation with the intention of quickly building a site that could threaten London, 200km to the north west. La Coupole's predecessor as launch site was the nearby blockhouse at Eperleques which had been found to be too vulnerable to aerial bombardment.
Railway tunnels were bored underground to allow the rocket parts to be brought in safely. In total more than 6km of galleries were dug by the Soviet prisoners in order to store the rockets 42m underground. A liquid oxygen fuel plant was also built to supplement the supply from the now redeployed Eperleques site and underground barracks and administrative areas were dug out and lined with concrete.
In January 1944 an enormous concrete dome was built over the top of the facility, giving the site its name. The dome was 71m in diameter, 5m thick and weighing an estimated 55,000 tonnes.
The Nazi engineers were able to build such a vast structure using poured reinforced concrete by moulding the chalk beneath into a convex shape and then laying the concrete on top. Once it had set, they quarried the chalk away from underneath, leaving a hollow space below the dome. Underneath this space was laid a second concrete layer, the gap between adding to the dome's bomb resistance.
Directly beneath this structure a vast hexagonal room, 21m high, was planned to house the rocket production facility. Once assembled and fuelled the rockets were to be moved outside and fired, at a maximum rate of 50 every 24 hours.
The French resistance informed the British of the devastating potential of La Coupole soon after construction began. The first attempts to destroy it however did not take place until March 1944 by which time the protective dome had already been finished. Over the following five months, 3,000 tonnes of Allied bombs were dropped on La Coupole but failed to make any impact on the facility itself, which was safely underground. A 5 ton Tallboy bomb caused some damage to the surrounding chalk but the dome remained intact.
The site was closed down before it was completed and before it had fired a rocket in July 1944. Hitler ordered its abandonment and the Soviet prisoners were put on trains and sent back to Germany. They have never been traced.
The site is open to the public as a museum dedicated to the human cost of La Coupole as well as the legacy of the V2 to modern rocketry.
