Mulberry port

The Port Mulberry was an artificial harbor built during the Second world war to allow the provisioning of the armies allied in the days which followed the Débarquement of Normandy. Two ports were assembled to broad of the beaches Normans but only that of Arromanches will be operational.

Context

The failure of the raid of Dieppe of 1942 showed that the Allies would have much difficulty of taking a large port of the French coast of the English Channel, the most strengthened elements Atlantic Wall created by the Germans along the coasts. The control of a port was necessary as of the following days the unloading to convey vehicles, supply and men to support the Opération Overlord. The Mulberry port, transportable artificial harbor in " kit" and that one could go up to broad of the beaches of the unloading was going to be the answer to this difficulty.

The name of the man at the origin of the idea of the Mulberry port is disputed, but one finds some Hugh Iorys Hughes, a Welsh engineer who subjected the initial plans of the idea to the British War Office , the professor J.D. Bernal and the Vice-admiral John Hughes-Hallett. At a meeting according to the failure of the Unloading of Dieppe, this last declared that if a port could not be taken, then it would be necessary to bring one of them. The idea, on the blow, was taken as a joke, but Churchill was interested in it and the concept of the Mulberries ports started to take form when Hughes-Hallett was named chief of the naval staff of the Overlord operation.

A test of 3 designs different of artificial harbor was launched and tested in reality in the Solway Firth in Scotland. Hugh Iorys Hughes developed its piers " Hippo" and its bridges " Crocodile" , employing 1.000 people right to build the version of test; The " Swiss Roll " (Swiss beam) of Hamilton which consisted of a floating way and a system of flexible bridges supported by let us bridge floating conceived by Allan H Beckett. The test gave varied results (the Swiss beam could carry only trucks of 7 tons maximum in the usual swell). However the final choice was done at the time of a storm during which the " Swiss Roll" was carried and the " Hippos" were sapped by sea water. The floating ways of Beckett (which had code name Whale ) did not suffer damage. They were thus retained. The ports proposed were made many and enormous Caisson S mobiles which once conveyed on the spot was filled with water and of which only the high part emerged from the floods, thus forming dams of protection and piers. Under the protection of its dams, floating unquestionable quays of unloading whose, connected to the beach by a series of bridges made it possible to unload the material by boats with strong tonnage. Metal footbridges, called “Dukws”, were used as floating road. After the war, some of these footbridges were re-used as for a bridge right beside the railway bridge of Bordeaux

The boxes were built in various places of Great Britain, mainly in the existing shipyards or on broad beaches like Conwy Morfa, along the British coast. Work was entrusted to privately held companies of construction like Robert McAlpine, Peter Lind & Company and Balfour Beatty who exist still nowadays. They were then towed through the English Channel to the coasts Normans at the speed of 8 km/h.

Complete Mulberry required 600.000 tons of concrete with 33 piers and had 15 km of floating roads to convey men and vehicles for the dry land. Boxes are still visible nowadays with broad of Arromanches and one, accessible to low tide, is ensablé in the estuary of the Thames.

The storm

The June 9th, just three days after the D-day, two ports, Mulberry code name has and Mulberry B, were built respectively with Saint-Laurent-on-Sea (in front of the beach of Omaha Beach) for the Americans and with Arromanches for the English Canadians. These ports were programmed to return in function in J+21 i.e. on June 27th and to last 3 months. But on June 19th, a storm rose and was going to last 3 days producing of wind forces 6 to 7 are 45-60 km/h with hollows from 2 to 3 meters. This storm caused considerable damage on Mulberry has, the American port vis-a-vis Omaha Beach and less widths on that British of Arromanches. On the American port, the boxes mole had been run out of too deep water and the blockships , these old boats run in protection in front of the boxes were spaced too much. Blow, they could not prevent the swell penetrating in the port and from devastating the quay and ways of unloading. It was thus to decide to stop construction and to give up the American port. It would be " cannibalisé" to repair and improve the British port which was called Port Winston . It is estimated that this storm caused a deficit of 20.000 vehicles and 140.000 tons of supply.

Real utility of Mulberry

This port was often proposed as having allowed the success of the Bataille of Normandy and often presented like one of the more good examples of genius and military logistics. The historians relativize from now on a little his role. 35 to 48% of British tonnage forwarded by the port of Arromanches between on June 6th and on August 31st and much less the first weeks: 12% at June 19th and 19,6% at the beginning of July. The Americans although private of port and without using that of Arromanches unloaded 40% of tons more than their Anglo-Canadian allies (10 000 tons per day against 6.000). What reduces to 25% the total volume passed by the artificial harbor. A technique of stranding to large scales by low tide of large barges of unloading, a possible use more important than envisaged ports secondary such that of Courseulles because taken in enough good state allowed these unloadings. It is not that post-war period the Allies estimated that from a logistic point of view, they could undoubtedly have done without a port and especially that the time and the money devoted to their construction could have been used better in the effort of war. But the existence of such a structure allowed Allied not being focused immediately on the catch of a port in the weeks following the unloading as opposed to what thought the Germans. These 2 ports thus played a big role in the strategy of Overlord.

See too

Operation PLUTO

References

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