Mulberry harbour
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Arromanches_Caissons.jpg
A Mulberry Harbour was a type of temporary harbour developed in World War II to offload cargo on a beach during the Allied invasion of Normandy.
The actual proposer of the idea of the Mulberry Harbour is disputed, but among those who are known to have proposed something along these lines is Hugh Iorys Hughes, a Welsh civil engineer who submitted initial plans on the idea to the War Office, Professor J. D. Bernal, and Vice-Admiral John Hughes-Hallett. At a meeting following the Dieppe Raid he declared that if a port could not be captured, then one should be taken across the Channel. Although this was met with derision at the time, the concept of Mulberry Harbours began to take shape when Hughes-Hallett moved to be Naval Chief of Staff to the Overlord planners.
Developed by J. D. Bernal and Brigadier Bruce White, under the orders of Sir Winston Churchill, the harbours called for many huge caissons, or barges filled with cement, to be towed across the English Channel and sunk to create a breakwater. This plan was carried out and by June 9, just 3 days after D-Day, two harbours codenamed Mulberry 'A' and 'B' were constructed at Omaha Beach and Arromanches, respectively. However, a large storm on June 19 destroyed the American harbour at Omaha, leaving only the British harbour at Arromanches. In the 100 days after D-Day, this harbour, which came to be known as Port Winston, was used to land over 2.5 million men, 500,000 vehicles, and 4 million tonnes of supplies providing much needed reinforcements in France.
From a technical perspective, a Mulberry harbour was constructed out of 600,000 tons of concrete between 33 jetties, and had 10 miles of floating roadways to land men and vehicles on the beach. The caissons that were sunk to form the breakwater were towed across the English Channel at only 5 mph. While the harbour at Omaha was destroyed rather quickly, Port Winston saw heavy use for 8 months—despite being designed to last only 3 months. Port Winston is commonly upheld as one of the best examples of military engineering. Its remains are still visible today from the beaches at Arromanches.